bsodium hydrogen carbonate


To absorb the more volatile hydrogen chloride fumes produced during the vigorous reaction and by reacting with the acid to produce more carbon IVoxide gas


Chemical equation


NaHCO3s  HClaq  Na2CO3 aq  H2Ol  CO2 g


cconcentrated sulphuricVIacid


To dry the gasas a drying agent


4Describe the smell of carbonIVoxide gas


Colourless and odourless


5 Effect on lime water


Experiment


Bubbled carbonIVoxide gas into a test tube containing lime water for about three minutes


Observation


White precipitate is formed


White precipitate dissolved when excess carbonIVoxide gas is bubbled


Explanation


CarbonIVoxide gas reacts with lime waterCaOH2 to form an insoluble white precipitate of calcium carbonate Calcium carbonate reacts with more CarbonIV oxide gas to form soluble Calcium hydrogen carbonate


CaOH2aq  CO2 g  CaCO3 s  H2Ol


CaCO3 aq  H2Ol  CO2 g  CaHCO3 2 aq


6 Effects on burning Magnesium ribbon


Lower a piece of burning magnesium ribbon into a gas jar containing carbon IVoxide gas


The ribbon continues to burn with difficulty


White ashsolid is formed


Black specksolidparticles formed on the side of gas jar


Carbon IV oxide gas does not support combustionburningMagnesium burn to producerelease enough heat energy to decompose Carbon IV oxide gas to carbon and oxygenMagnesium continues to burn in Oxygen forming white Magnesium Oxide solidashBlack speckparticle of carboncharcoal residue forms on the sides of reaction flask During the reaction Carbon IV oxide is reduced Oxidizing agentto carbon while Magnesium is Oxidized to Magnesium Oxide


Chemical equation


2Mgs  CO2 g  C s  2MgOl


7 Dry and wet litmus papers were separately put in a gas jar containing dry carbon IV oxide gas State and explain the observations made


Blue dry litmus paper remain blue


Red dry litmus paper remain Red


Blue wetdampmoist litmus paper turns red


Red wetdampmoist litmus paper remain red


Explanation


Dry Carbon IV oxide gas is a molecular compound that does not dissociateionize to release H and thus has no effect on litmus papers


Wetdampmoist litmus paper contains water that dissolvesreact with dry carbon IV oxide gas to form the weak solution of carbonic IV acid H2CO3


Carbonic IV acid dissociateionizes to a few little free H and CO32


The few H aq ions are responsible for turning blue litmus paper to faint red showing the gas is very weakly acidic


H2CO3aq  2H aq  CO32aq


8 Explain why Carbon IV oxide cannot be prepared from the reaction of


i Marble chips with dilute sulphuric VI acid


Reaction forms insoluble calcium sulphate VI that covercoat unreacted marble chips stopping further reaction


CaCO3s  H2SO4 aq  CaSO4 s  H2Ol  CO2 g


PbCO3s  H2SO4 aq  PbSO4 s  H2Ol  CO2 g


BaCO3s  H2SO4 aq  BaSO4 s  H2Ol  CO2 g


ii Lead II carbonate with dilute Hydrochloric acid


Reaction forms insoluble Lead IIChloride that covercoat unreacted LeadII carbonate stopping further reaction unless the reaction mixture is heated Lead II Chloride is soluble in hot water


Chemical equation


PbCO3s  2HCl aq  PbCl2 s  H2Ol  CO2 g


9 Describe the test for the presence of Carbon IV oxide


Using burning splint


Lower a burning splint into a gas jar suspected to contain Carbon IV oxide gas The burning splint is extinguished


Using Lime water


Bubble the gas suspected to be Carbon IV oxide gas A white precipitate that dissolves in excess bubbling is formed


CaOH2aq  CO2 g  CaCO3 s  H2Ol


CaCO3 aq  H2Ol  CO2 g  CaHCO3 2 aq


10State three main uses of Carbon IVoxide gas


iIn the Solvay process for the manufacture of soda ashsodium carbonate


iiIn preservation of aerated drinks


iiiAs fire extinguisher because it does not support combustion and is denser than air


ivIn manufacture of Baking powder


ii Carbon II Oxide CO


aOccurrence


Carbon II oxide is found is found from incomplete combustion of fuels like petrol charcoal liquefied Petroleum GasLPG


bSchool Laboratory preparation


In the school laboratory carbonIIoxide can be prepared from dehydration of methanoic acidFormic acidHCOOH or Ethan12dioic acidOxalic acidHOOCCOOH using concentrated sulphuricVI acid Heating is necessary


cProperties of Carbon II OxideQuestions


1 Write the equation for the reaction for the preparation of carbonIIoxide using


iMethod 1


Chemical equation


HOOCCOOHs ConcH2SO4 COg  CO2 g  H2Ol


H2C2O4s ConcH2SO4 COg  CO2 g  H2Ol


iiMethod 2


HCOOHs ConcH2SO4 COg  H2Ol


H2CO2s ConcH2SO4 COg  H2Ol


2 What method of gas collection is used during the preparation of carbon II oxide


Over water because the gas is insoluble in water


Downward delivery because the gas is 1  times denser than air


3 What is the purpose of


i Potassium hydroxidesodium hydroxide in Method 1


To absorb remove carbon II oxide produced during the reaction


2KOH aq  CO2 g  K2CO3 s  H2Ol


2NaOH aq  CO2 g  Na2CO3 s  H2Ol


ii Concentrated sulphuricVIacid in Method 1 and 2


Dehydrating agent removes the element of water Hydrogen and Oxygen in ratio 21 present in both methanoic and ethan12dioic acid


4 Describe the smell of carbon II oxide


Colourless and odourless


5 State and explain the observation made when carbonIVoxide is bubbled in lime water for a long time


No white precipitate is formed


6 Dry and wetmoistdamp litmus papers were separately put in a gas jar containing dry carbon IV oxide gas State and explain the observations made


Observation


blue dry litmus paper remains blue


red dry litmus paper remains red


wetmoistdamp blue litmus paper remains blue


wetmoistdamp red litmus paper remains red


Explanation


CarbonIIoxide gas is a molecular compound that does not dissociate ionize to release H ions and thus has no effect on litmus papers CarbonIIoxide gas is therefore a neutral gas


7 Carbon II oxide gas was ignited at the end of a generator as below


iState the observations made in flame K


Gas burns with a blue flame


iiWrite the equation for the reaction taking place at flame K


2COg  O2 g  2CO2 g


8 Carbon II oxide is a reducing agent Explain


Experiment


Pass carbon II oxide through glass tube containing copper II oxide Ignite any excess poisonous carbon II oxide


Colour change from black to brown Excess carbon II oxide burn with a blue flame


Carbon is a reducing agent It is used to reduce metal oxide ores to metal itself oxidized to carbon IV oxide gas Carbon II Oxide reduces black copper II oxide to brown copper metal


Chemical Equation


CuOs  COg  Cus  CO2g


black brown


PbOs  COg  Pbs  CO2g


brown when hot grey


yellow when cool


ZnOs  COg  Zns  CO2g


yellow when hot grey


white when cool


Fe2O3s  3COs  2Fes  3CO2g


brown when hotcool grey


Fe3O4 s  4COg  3Fes  4CO2g


These reactions are used during the extraction of many metals from their ore


9 Carbon II oxide is a pollutant Explain


Carbon II oxide is highly poisonoustoxicIt preferentially combine with haemoglobin to form stable carboxyhaemoglobin in the blood instead of oxyhaemoglobinThis reduces the free haemoglobin in the blood causing nausea coma then death


10 The diagram below show a burning charcoal stoveburnerjiko Use it to answer the questions that follow


Explain the changes that take place in the burner


Explanation


Charcoal stove has air holes through which air enters Air oxidizes carbon to carbon IV oxide gas at region I This reaction is exothermic H producing more heat


Chemical equation


Cs  O2g  CO2g


Carbon IV oxide gas formed rises up to meet more charcoal which reduces it to Carbon II oxide gas


2CO2 g  O2g  2CO g


At the top of burner in region II Carbon IIoxide gas is further oxidized to CarbonIVoxide gas if there is plenty of air but escape if the air is limited poisoning the living things around


2CO g  O2g  2CO2 g


excess air


11 Describe the test for the presence of carbonIIoxide gas


Experiment


BurnIgnite the pure sample of the gas PassBubble the products into lime waterCalcium hydroxide


Observation


Colourless gas burns with a blue flame A white precipitate is formed that dissolve on further bubbling of the products


2CO g  O2g  2CO2 g gas burns with blue flame


CaOH 2 aq  CO2 g  CaCO3 s  H2Ol


CO2 g  CaCO3 s  H2Ol  CaHCO3 2 aq


12 State the main uses of carbon IIoxide gas


i As a fuel water gas


iiAs a reducing agent in the blast furnace for extracting iron from iron oreMagnetiteHaematite


iiiAs a reducing agent in extraction of Zinc from Zinc oreZinc blende


iv As a reducing agent in extraction of Lead from Lead oreGalena


v As a reducing agent in extraction of Copper from Copper iron sulphideCopper pyrites


iiiCarbonateIV CO32and hydrogen carbonateIVHCO3


1Carbonate IV CO32 are normal salts derived from carbonicIVacid H2CO3 and hydrogen carbonate IV HCO3 are acid salts derived from carbonicIVacid


CarbonicIVacidH2CO3 is formed when carbonIVoxide gas is bubbled in water It is a dibasic acid with two ionizable hydrogens


H2CO3aq 2Haq  CO32aq


H2CO3aq  Haq  HCO3  aq


2Carbonate IV CO32 are insoluble in water except Na2CO3  K2CO3 and NH42CO3


3Hydrogen carbonate IV HCO3 are soluble in water Only five hydrogen carbonates exist Na HCO3  KHCO3 NH4HCO3 CaHCO32 and MgHCO32


CaHCO32 and MgHCO32 exist only in aqueous solutions


3The following experiments show the effect of heat on Carbonate IV CO32 and Hydrogen carbonate IV HCO3 salts


Experiment


In a clean dry test tube place separately about 10 of the following


ZincIIcarbonateIV sodium hydrogen carbonateIV sodium carbonateIV Potassium carbonateIV ammonium carbonateIV potassium hydrogen carbonateIV LeadIIcarbonateIV IronIIcarbonateIV and copperIIcarbonateIV Heat each portion gently the strongly Test any gases produced with lime water


Observation


iColorless droplets form on the cooler parts of test tube in case of sodium carbonateIV and Potassium carbonateIV


iiWhite residuesolid left in case of sodium hydrogen carbonateIV sodium carbonateIV Potassium carbonateIV and potassium hydrogen carbonateIV


iiiColour changes from bluegreen to black in case of copperIIcarbonateIV


iv Colour changes from green to brownyellow in case of Iron IIcarbonateIV


v Colour changes from white when cool to yellow when hot in case of Zinc II carbonateIV


vi Colour changes from yellow when cool to brown when hot in case of Lead II carbonateIV


viiColourless gas produced that forms a white precipitate with lime water in all cases


Explanation


1 Sodium carbonateIV and Potassium carbonateIV exist as hydrated salts with 10 molecules of water of crystallization that condenses and collects on cooler parts of test tube as a colourless liquid


Chemical equation


Na2CO3 10H2Os  Na2CO3 s  10H2Ol


K2CO3 10H2Os  K2CO3 s  10H2Ol


2 Carbonate IV CO32 and Hydrogen carbonate IV HCO3 salts decompose on heating except Sodium carbonateIV and Potassium carbonateIV


a Sodium hydrogen carbonateIV and Potassium hydrogen carbonateIV decompose on heating to form sodium carbonateIV and Potassium carbonateIVWater and carbonIVoxide gas are also produced


2NaHCO3 s  Na2CO3 s  H2Ol  CO2 g


white white


2KHCO3 s  K2CO3 s  H2Ol  CO2 g


b Calcium hydrogen carbonateIV and Magnesium hydrogen carbonateIV decompose on heating to form insoluble Calcium carbonateIV and Magnesium carbonateIVWater and carbonIVoxide gas are also produced


CaHCO32 aq  CaCO3 s  H2Ol  CO2 g


Colourless solution white


MgHCO32 aq  MgCO3 s  H2Ol  CO2 g


c Ammonium hydrogen carbonateIV decompose on heating to form ammonium carbonateIV Water and carbonIVoxide gas are also produced


2NH4HCO3 s  NH42CO3 s  H2Ol  CO2 g


dAll other carbonates decompose on heating to form the metal oxide and produce carbonIVoxide gas eg


MgCO3 s  MgO s  CO2 g


white solid white solid


Chemical equation


BaCO3 s  BaO s  CO2 g


CaCO3 s  CaO s  CO2 g


CuCO3 s  CuO s  CO2 g


bluegreen solid black solid


ZnCO3 s  ZnO s  CO2 g


white solid white solid when cool


Yellow solid when hot


PbCO3 s  PbO s  CO2 g


white solid yellow solid when cool


brown solid when hot


4The following experiments show the presence of Carbonate IV CO32 and Hydrogen carbonate IV HCO3 ions in sample of a salt


aUsing LeadII nitrateV


I Using a portion of salt solution in a test tube add four drops of LeadIInitrateVsolutionPreserve


II To the preserved solution add six drops of dilutte nitricVacid Preserve


II To the preserved sample that forms a precipitate heat to boil


II To the preserved sample that do not form a precipitate add three drops of acidified potassium manganateVIIlime water


ExperimentsObservations


bUsing BariumIInitrateV BariumIIchloride


I To about 5cm3 of a salt solution in a test tube add four drops of BariumII nitrate V  BariumIIchloride Preserve


II To the preserved sample in I above add six drops of 2M nitricV acid  Preserve


Observation 1


Observation 2


IIITo the preserved sample observation 2 in II above add 4 drops of acidified potassium manganateVII dichromateVI


Explanations


Using LeadIInitrateV


iLeadIInitrateV solution reacts with chloridesCl Sulphate VI salts SO42  Sulphate IVsalts SO32 and carbonatesCO32 to form the insoluble white precipitate of LeadIIchloride LeadIIsulphateVI LeadII sulphate IV and LeadIIcarbonateIV


Chemicalionic equation


Pb2aq  Cl aq  PbCl2s


Pb2aq  SO42 aq  PbSO4 s


Pb2aq  SO32 aq  PbSO3 s


Pb2aq  CO32 aq  PbCO3 s


iiWhen the insoluble precipitates are acidified with nitricV acid


LeadIIchloride and LeadIIsulphateVI do not react with the acid and thus their white precipitates remain persists


LeadII sulphate IV and LeadIIcarbonateIV reacts with the acid to form soluble LeadII nitrate V and produceeffervescesfizzesbubbles out sulphurIVoxide and carbonIVoxide gases respectively


PbSO3 s  2Haq  H2 O l  Pb2aq  SO2 g


PbCO3 s  2Haq  H2 O l  Pb2aq  CO2 g


iiiWhen LeadIIchloride and LeadIIsulphateVI are heatedwarmed


LeadIIchloride dissolves in hot wateron boilingrecrystallizes on cooling


LeadIIsulphateVI do not dissolve in hot water thus its white precipitate persistsremains on heatingboiling


ivWhen sulphurIVoxide and carbonIVoxide gases are produced


sulphurIVoxide will decolorize acidified potassium manganateVII and  or Orange colour of acidified potassium dichromateVI will turns to green CarbonIVoxide will not


Chemical equation


5SO32aq  2MnO4 aq 6Haq  5SO42aq  2Mn2aq  3H2Ol


purple colourless


3SO32aq  Cr2O72aq 8Haq  3SO42aq  2Cr3aq  4H2Ol


Orange green


CarbonIVoxide forms an insoluble white precipitate of calcium carbonate if three drops of lime water are added into the reaction test tube when effervescence is taking place SulphurIVoxide will not


CaOH2aq  CO2 g  CaCO3s  H2Ol


These tests should be done immediately after acidifying to ensure the gases produced react with the oxidizing agentslime water


Using BariumIInitrateV BariumIIChloride


iBariumIInitrateV and or BariumIIchloride solution reacts with Sulphate VI salts SO42  Sulphate IVsalts SO32 and carbonatesCO32 to form the insoluble white precipitate of BariumIIsulphateVI BariumII sulphate IV and BariumIIcarbonateIV


Chemicalionic equation


Ba2aq  SO42 aq  BaSO4 s


Ba2aq  SO32 aq  BaSO3 s


Ba2aq  CO32 aq  BaCO3 s


Barium IIsulphateVI do not react with the acid and thus its white precipitates remain persists


BariumII sulphate IV and BariumIIcarbonateIV reacts with the acid to form soluble BariumII nitrate V and produce effervesces fizzes bubbles out sulphurIVoxide and carbonIVoxide gases respectively


BaSO3 s  2Haq  H2 O l  Ba2aq  SO2 g


BaCO3 s  2Haq  H2 O l  Ba2aq  CO2 g


iii When sulphurIVoxide and carbonIVoxide gases are produced


Chemical equation


purple colourless


Orange green


iii Sodium carbonateIV Na2CO3


aExtraction of sodium carbonate from soda ash


Sodium carbonate naturally occurs in Lake Magadi in Kenya as Tronatrona is the double salt  sodium sesquicarbonate NaHCO3 Na2CO3 H2OIt is formed from the volcanic activity that takes place in Lake Naivasha Nakuru Bogoria and Elementeita All these lakes drain into Lake Magadi through underground rivers Lake Magadi has no outlet


Solubility of Trona decrease with increase in temperatureHigh temperature during the day causes trona to naturally crystallize It is mechanically scoopeddredgeddug and put in a furnace


Inside the furnace trona decompose into soda ashsodium carbonate


2NaHCO3 Na2CO3 H2O s  3Na2CO3 s  5H2Ol  CO2 g


trona soda ash


Soda ash is then bagged and sold as Magadi sodaIt is mainly used


iin making glass to lower the melting point of raw materials sandSiO2 from 1650oC and CaO from 2500oC to around 1500oC


iiin softening hard water


iiiin the manufacture of soapless detergents


ivSwimming pool pH increaser


Sodium chloride is also found dissolved in the lake Solubility of sodium chloride decrease with decreases in temperature sodium chloride has lower solubility at lower temperatures When temperatures decrease at night it crystallize out The crystals are then mechanically dugdredged scooped then packed for sale as animalcattle feeds and seasoning food


Summary flow diagram showing the extraction of Soda ash from Trona


bThe Solvay process for industrial manufacture of sodium carbonateIV


iRaw materials


Brine Concentrated Sodium chloride from salty seaslakes


Ammonia gas from Haber


Limestone Calcium carbonate from chalk limestone rich rocks


Water from riverslakes


iiChemical processes


Ammonia gas is passed up to meet a downward flow of sodium chloride solution  brine to form ammoniated brineammoniacal brine mixture in the ammoniated brine chamber


The ammoniated brine mixture is then pumped up atop the carbonator solvay tower


In the carbonator solvay tower ammoniated brineammoniacal brine mixture slowly trickle down to meet an upward flow of carbonIVoxide gas


The carbonator is shelved packed with quartzbroken glass to


i reduce the rate of flow of ammoniated brineammoniacal brine mixture


iiincrease surface area of the liquid mixture to ensure a lot of ammoniated brineammoniacal brine mixture react with carbonIVoxide gas


Insoluble sodium hydrogen carbonate and soluble ammonium chloride are formed from the reaction


Chemical equation


CO2g  H2Ol  NaCl aq  NH3g  NaHCO3s  NH4Claq


The products are then filtered Insoluble sodium hydrogen carbonate forms the residue while soluble ammonium chloride forms the filtrate


Sodium hydrogen carbonate itself can be used


i as baking powder and preservation of some soft drinks


ii as a buffer agent and antacid in animal feeds to improve fibre digestion


iii making dry chemical fire extinguishers


In the Solvay process Sodium hydrogen carbonate is then heated to form Sodium carbonatesoda ash water and carbon IV oxide gas


2NaHCO3 s  Na2CO3s  CO2g  H2Ol


Sodium carbonate is stored ready for use in


i during making glasslowering the melting point of mixture of sandSiO2 from 1650oC and CaO from 2500oC to around 1500oC


ii in softening hard water


iii in the manufacture of soapless detergents


iv swimming pool pH increaser


Water and carbonIVoxide gas are recycled back to the ammoniated brineammoniacal brine chamber


More carbonIVoxide is produced in the kilnfurnace Limestone is heated to decompose into Calcium oxide and carbonIVoxide


CaCO3 s  CaOs  CO2g


CarbonIVoxide is recycled to the carbonatorsolvay tower Carbon IVoxide is added water in the slaker to form Calcium hydroxide This process is called slaking


Chemical equation


CaOs  H2O l  CaOH2 aq


Calcium hydroxide is mixed with ammonium chloride from the carbonatorsolvay tower in the ammonia regeneration chamber to form Calcium chloride water and more ammonia gas


CaOH2 aq 2NH4Cl aq  CaCl2s  2NH3g  H2Ol


NH3g and H2Ol are recycled


Calcium chloride may be used


ias drying agent in the school laboratory during gas preparation except ammonia gas


iito lower the melting point of solid sodium chloride  rock salt salts during the Downs process for industrial extraction of sodium metal


Detailed Summary flow diagram of Solvay Process


Practice


1 The diagram below shows part of the Solvay process used in manufacturing sodium carbonate Use it to answer the questions that follow


aExplain how Sodium Chloride required for this process is obtained from the sea


Sea water is pumped scooped into shallow pods Evaporation of most of the water takes place leaving a very concentrated solution


bi Name process


I Filtration


II Decomposition


ii Write the equation for the reaction in process


Process I


Chemical equation


CO2g  H2Ol  NaCl aq  NH3g  NaHCO3s  NH4Claq


Process II


2NaHCO3 s  Na2CO3s  CO2g  H2Ol


ci Name two substances recycled in the solvay process


Ammonia gas  CarbonIVOxide and Water


iiWhich is the byproduct of this process


CalciumIIChloride CaCl2


iiiState two uses that the byproduct can be used for


As a drying agent in the school laboratory preparation of gases


In the Downs cellprocess for extraction of Sodium to lower the melting point of rock salt


ivWrite the chemical equation for the formation of the byproducts in the Solvay process


CaOH2 aq 2NH4Cl aq  CaCl2s  2NH3g  H2Ol


dIn an experiment to determine the  purity of Sodium carbonate produced in the Solvay process 215g of the sample reacted with exactly 400cm3 of 05M Sulphuric VIacid


iCalculate the number of moles of sodium carbonate that reacted


Na2CO3 aq H2SO4 aq  Na2SO4 aq CO2g  H2Ol


Mole ratio Na2CO3 H2SO4  11


Moles H2SO4  Molarity x Volume  05 x 400  002 Moles


1000 1000


Moles of Na2CO3  002 Moles


iiDetermine the  of sodium carbonate in the sample


Molar mass of Na2CO3  106g


Mass of Na2CO3  moles x Molar mass  002 x 106  212 g


of Na2CO3   212 g x 100  986047


e State two uses of soda ash


i during making glasslowering the melting point of mixture of sandSiO2 from 1650oC and CaO from 2500oC to around 1500oC


ii in softening hard water


iii in the manufacture of soapless detergents


iv swimming pool pH increaser


fThe diagram below shows a simple ammonia soda tower used in manufacturing sodium carbonate Use it to answer the questions that follow


iName the raw materials needed in the above process


Ammonia


Water


CarbonIVoxide


Limestone


Brine Concentrated sodium chloride


iiIdentify substance A


Ammonium chloride NH4Cl


iii Write the equation for the reaction taking place in


ITower


Chemical equation


CO2g  NaCl aq  H2Ol  NH3g  NaHCO3s  NH4Claq


II Production of excess carbon IVoxide


CaCO3 s  CaOs  CO2g


III The regeneration of ammonia


CaOH2 aq 2NH4Cl aq  CaCl2s  2NH3g  H2Ol


ivGive a reason for having the circular metal plates in the tower


To slow the downward flow of brine


To increase the rate of dissolving of ammonia


To increase the surface area for dissolution


vName the gases recycled in the process illustrated above


Ammonia gas  CarbonIVOxide and Water


2 Describe how you would differentiate between carbon IVoxide and carbonIIoxide using chemical method


Method I


Bubble both gases in lime waterCaOH2


white precipitate is formed if the gas is carbon IV oxide


No white precipitate is formed if the gas is carbon II oxide


Method II


ignite both gases


Carbon IV oxide does not burnignite


Carbon II oxide burn with a blue nonsooty flame


Method III


Lower a burning splint into a gas containing each gas separately


burning splint is extinguished if the gas is carbon IV oxide


burning splint is not extinguished if the gas is carbon II oxide


3Using Magnesium sulphateVIsolution describe how you can differentiate between a solution of sodium carbonate from a solution of sodium hydrogen carbonate


Add Magnesium sulphateVI solution to separate portions of a solution of sodium carbonate and sodium hydrogen carbonate in separate test tubes


White precipitate is formed in test tube containing sodium carbonate


No white precipitate is formed in test tube containing sodium hydrogen carbonate


Chemical equation


Na2CO3 aq MgSO4 aq  Na2SO4 aq  MgCO3s


white ppt


Ionic equation


CO32 aq  Mg2 aq  MgCO3s


2NaHCO3 aq MgSO4 aq  Na2SO4 aq  MgHCO32 aq


colourless solution


4 The diagram below shows a common charcoal burner Assume the burning take place in a room with sufficient supply of air


aExplain what happens around


iLayer A


Sufficientexcess air oxygen enter through the air holes into the burner It reacts withoxidizes Carbon to carbonIVoxide


Cs  O2g  CO2 g


iiLayer B


Hot carbonIVoxide rises up and is reduced by more carboncharcoal to carbon IIoxide


Cs  CO2g  2CO g


iiLayer C


Hot carbonIIoxide rises up and burns with a blue flame to be oxidized by the excess air to form carbonIVoxide


2CO g  O2g  2CO2g


bState and explain what would happen if the burner is put in an enclosed room


The hot poisonous toxic carbonIIoxide rising up will not be oxidized to CarbonIVoxide


cUsing a chemical test describe how you would differentiate two unlabelled black solids suspected to be charcoal and copperIIoxide


Method I


BurnIgnite the two substances separately


Charcoal burns with a blue flame


CopperIIoxide does not burn


Method II


Add dilute sulphuricVIacidNitricVacidHydrochloric acid separately


Charcoal does not dissolve


CopperIIoxide dissolves to form a colourless solution


5 Excess CarbonIIoxide was passed over heated copperIIoxide as in the set up shown below for five minutes


aState and explain the observations made in the combustion tube


Observation


Colour change from black to brown


Explanation


Carbon IIoxide reduces black copperIIoxide to brown copper metal itself oxidized to CarbonIVoxide


Chemical equation


COg  CuO s  Cus  CO2g


black brown


b iName the gas producing flame A


CarbonIIoxide


iiWhy should the gas be burnt


It is toxicpoisonous


iiiWrite the chemical equation for the production of flame A


2COg  O2g  2CO2g


cState and explain what happens when carbonIVoxide is prepared using Barium carbonate and dilute sulphuricVIacid


Reaction starts then stops after sometime producing smalllittle quantity of carbonIVoxide gas


Barium carbonate react with dilute sulphuricVIacid to form insoluble Barium sulphateVI that covercoat unreacted Barium carbonate stopping further reaction to produce more CarbonIVoxide


d Using dot  and crossx to represent electrons show the bonding in a molecule of


i CarbonIIoxide


ii CarbonIVOxide


e Carbon IVoxide is an environmental pollutant of global concern Explain


It is a green house gas thus causes global warming


It dissolves in water to form acidic carbonic acid which causes acid rain


fExplain using chemical equation why lime water is used to test for the presence of Carbon IV oxide instead of sodium hydroxide


Using lime watercalcium hydroxide


a visible white precipitate of calcium carbonate is formed that dissolves on bubbling excess Carbon IV oxide gas


Chemical equation


CaOH2aq  CO2 g  CaCO3 s  H2Ol


white precipitate


CaCO3 aq  H2Ol  CO2 g  CaHCO3 2 aq


Using sodium hydroxide


No precipitate of sodium carbonate is formed Both sodium carbonate and sodium hydrogen carbonate are soluble saltsdissolves


2NaOH aq  CO2 g  Na2CO3 s  H2Ol


No white precipitate


Na2CO3 s  H2Ol  CO2 g  2NaHCO3 s


gEthan12dioic acid and methanoic acid may be used to prepare small amount of carbonIIoxide in a school laboratory


i Explain the modification in the set up when using one over the other


Before carbonIIoxide is collected


when using methanoic acid no concentrated sodiumpotassium hydroxide is needed to absorb CarbonIVoxide


when using ethan12dioic acid concentrated sodiumpotassium hydroxide is needed to absorb CarbonIVoxide


iiWrite the equation for the reaction for the formation of carbonIIoxide from


IMethanoic acid


Chemical equation HCOOHaq  COg  H2Ol


II Ethan12dioic acid


Chemical equation HOOCCOOHaq  CO2gCOgH2Ol


hBoth carbonIIoxide and carbonIVoxide affect the environment Explain why carbonIIoxide is more toxicpoisonous


Both gases are colourlessdenser than water and odourless


CarbonIIoxide is preferentially absorbed by humanmammalian haemoglobin when inhaled forming stable carboxyhaemoglobin instead of oxyhaemoglobinThis reduces the free haemoglobin in the blood leading to suffocation and quick death CarbonIVoxide is a green house gas that increases global warming


CarbonIIoxide is readily oxidized to carbonIVoxide


6Study the flow chart below and use it to answer the questions that follow


aName


ithe white precipitate A


Calcium carbonate


ii solution B


Calcium hydrogen carbonate


iii gas C


CarbonIVoxide


iv white residue B


Calcium oxide


v solution D


Calcium hydroxidelime water


bWrite a balanced chemical equation for the reaction for the formation of


i the white precipitate A from solution D


Chemical equation


CaOH2aq  CO2 g  CaCO3 s  H2Ol


ii the white precipitate A from solution B


CaHCO32aq  CO2 g  CaCO3 s  H2Ol


iii solution B from the white precipitate A


CO2 g  CaCO3 s  H2Ol  CaHCO32aq


iv white residue B from the white precipitate A


CaCO3s  CO2 g  CaO s


iv reaction of white residue B with water


CaO s  H2Ol  CaOH2aq


CHEMISTRY OF CHLORINE


ACHLORINE


Chlorine is a nonmetallic element in group VII Group 17 of the periodic table It has electronic configuration 287 It gains one valence election to form stable Clion it belongs to the chemical family of halogens


Occurrence


As Brineconcentration sodium chloride solution dissolved in salty seas water oceans and lakes eg Lake Magadi in Kenya is very salty


As rocksalt solid sodium chloride crystals in the earths crust all over the world


B Preparation


Chlorine gas may be prepared in the school laboratory from the following


aHeating solid Manganese iv Oxide and Concentrated Hydrochloric acid


b Heating Lead IV Oxide and concentrated hydrochloric acid


cReacting Potassium Manganate VII with concentrated Hydrochloric acid


dReacting Potassium sodium Dichromate VI Acid with Concentrated Hydrochloric acid


Set up of school laboratory preparation of chlorine


c Properties of chlorine Questions


1 What is the colour of chlorine


Pale green


2 Describe the smell of chlorine


Pungent irritating smell


3 What method is used in collection of chlorine gas explain


Downward delivery


Chlorine is 112 denser than air


4i What is the purpose of concentrated sulphuric VI acid


To dry the gas


ii Name two other substances that can be used in place of concentrated sulphuric VI acid


Calcium chloride


Silica gel


iii Name a substance that cannot be used in place of concentrated sulphuric VI acid explain


Calcium oxide reacts with chlorine


5aWrite three possible reactions between concentrated hydrochloric acid and the oxidizing agents


2KMnO4s 16HClaq  2KClaq2MnCl2aq  8H2Ol  5Cl2g


2K2Cr2O7s 14HClaq  2KClaq  2CrCl3aq  7H2Ol  3Cl2g


3Na2Cr2O7s  14HClaq  2NaClaq  CrCl3aq  7H2Ol  3Cl2g


4PbO2s  4HClaq  PbCl2aq  Cl2g  2H2Ol


5MnO2s 4HClaq  MnCl2aq  Cl2g  2H2Ol


b Why is Hydrochloric acid used in all the above cases


Oxidizing agents KMnO4PbO2MnO2K2Cr2ONa2Cr2O7 readily oxidize hydrochloric acid to chlorine themselves reduced to their chlorides


Generally


2HCl aq  O  Cl2 g  H2O l


From oxidizing agent


6 State and explain the observation made when chlorine is bubbled in water


Observation


Pale yellow colour of chlorine fades


yellow solution formed


Explanation


Chlorine dissolves then reacts with water to form yellow chlorine water Chlorine water is chemically a mixture of hydrochloric acid and chloricIacid hypochlorous acid


A mixture of hydrochloric acid and chloricIacid hypochlorous acid is commonly called Chlorine water


Chemical equation


Cl2g  H2Ol  HClaq  HClOaq


7 Chlorine water in a boiling tube inverted into a trough was exposed to sunlight for two hours Using a well labeled diagram show and explain the observations made


Chlorine I acid is an unstable compound


After two hours the chloric I acid in chlorine water decomposes to hydrochloric acid and releases oxygen gas This reaction takes place in sunlight


2HOClaq  2HClaq  O2 g


8 State and explain the observation made when chlorine gas is bubbled in gas jar containing dampwetmoist litmus papers


The blue litmus turns red then both the redblue litmus papers are bleacheddecolourized


Chlorine reacts with water in the litmus papers to form acidic hydrochloric acid and chloric l acid that turns blue litmus papers red


Chemical Equation


Unstable chloric I acid oxidizes the dyecolured litmus paper to colourless material


HClOaq  dye  HClaq  dye  O


coloured colourless


Or


HClOaq  dyeO  HClaq  dye


NB Chlorine does not therefore bleachdecolourize dry litmus paperdye because chloricI acid cannot be formed in absence of water


9 Blue litmus papers were put in a flask containing cold dilute sodium hydroxide Chlorine gas was bubbled into the solution State and explain the observations made


Observation


blue litmus papers were bleached decolorized


Pale green colour of chlorine fades


Explanation


Sodium hydroxide reacts with chlorine to form sodium chloride and sodium hypochlorite Sodium hypochlorite bleaches dyes by oxidation


Cl2  2NaOHaq  NaClaq  NaClOaq  H2O


NaClOaq  dye  NaClaq  dye  O


coloured Colourless


NaClOaq  dyeO  NaClaq  dye


Coloured Colourless


10Blue litmus papers were put in flask containing hot concentrated sodium hydroxide Chlorine gas was bubbled into the solution State and explain the observations made


blue litmus papers were bleached


Hot concentrated sodium hydroxide reacts with chlorine to form sodium chloride and sodium chloride VSodium chlorate V bleaches by oxidation


Chemical equation


2Cl2g  4NaOHaq  3NaClaq  NaClO3aq  H2Ol


NaClO3aq  3dyes  NaClaq  3dye  O


NaClO3aq  3dyesO  NaClaq  3 dyes


NaClO3 is also a weed killer


11 State three main use of chlorine gas


Manufacture of polyvinyl chloride PVC  polychloroethene pipes


Manufacture of hydrochloric acid used in Pickling of metals


Manufacture of bleaching agents


Chlorination of water to kill germs


12 The diagram below shows the effect of chlorine on heated iron wool


Method I


Method II


a Identify a suitable drying agent to dry chlorine gas


Conc H2SO4  Concentrated sulphuric VI acid


Anhydrous Calcium II Chloride


Silica gel


b State and explain the observations made in combustion tube in method I and II


Observation


Iron glows red hot


Brown crystals are formed


Explanation


Iron reacts with chlorine to form dark brown crystals of iron III Chloride


This reaction is exothermic and requires no farther heating once started


Iron III Chloride sublimes away ensuring the unreacted Iron completely reacts with chlorine gas


Chemical equation


2Fes  3Cl2 g  2FeCl3g


c i Why is the brown solid collected at the point as shown in method I and II


Heated iron III Chloride crystals sublime to gas and solidify on the cooler parts


ii Name another metal that can be used in place of iron to react with chlorine and collected at similar point on heating explain


Metal Aluminum


Aluminum reacts with chlorine to form a while sublimate of aluminum III chloride at the cooler parts


2Als  3Cl2g  2AlCl3sg


d What is the purpose of suction pump


To pull the gaseous products into the set up


e What is the function of


i Sodium hydroxide in method II Explain


To absorb poisonoustoxic excess unreacted chlorine gas


Sodium hydroxide reacts with chlorine to form sodium chloride Sodium hypochlorite and water


2NaOHaq  Cl2g  NaClaq  NaClOaq  H2Ol


2KOHaq  Cl2g  KClaq  KClOaq  H2Ol


ii Anhydrous calcium chloridecalcium oxide in method I Explain


To absorb moisturewater in the set up to prevent it from hydrolyzing iron III chloridealuminium oxide


Explanation


Iron III chloride and Aluminium chloride fumes and reacts with small traces of water to form a solution of iron III hydroxidealuminium hydroxide and hydrogen chloride gas


Chemical equation


FeCl3s  3HClaq  FeOH3aq  3HClg


AlCl3s  3HClaq  AlOH3aq  3HClg


f Based on e i and ii above what precaution should be made in


i method II to ensure correct results


Tube B should be completely dry to prevent hydrolysis of iron III Chloride to iron III hydroxide


ii Carrying out method I


Should be done in a fume chamber or in the open because chlorine gas is poisonoustoxic


g Name another substance that can be used place of Sodium hydroxide in method I


Potassium hydroxide


h Calcium oxide cannot be used in place of calcium chloride during preparation of chlorine Explain


Calcium oxide is a base It reacts absorbs water to form calcium hydroxide solution


Calcium hydroxide reacts with chlorine to form a mixture of calcium chloride and calcium hypochlorite


2Ca OH2aq  2Cl2g  CaCl2aq  CaOCl2aq  H2Ol


13 aState and explain the observation made when a piece of burning magnesium ribbon is lowered in a gas jar containing chlorine gas


Magnesium ribbon continues burning with a bright flame


White solid formed


Pale yellow colour of chlorine fades


Explanation


Magnesium reacts with chlorine forming a white solid of magnesium chloride


Chemical equation


Mgs  Cl2g  MgCl2s


b Write the equation for the reaction that takes place if zinc is used


Zns  Cl2g  ZnCl2s


14 Burning phosphorus was lowered in a gas jar containing chlorine gas


a State the observations made


Phosphorus continues to burn


Dense white fumes formed


Pale green colour of chlorine fades


b Write two possible equations that take place


P4s  6Cl2g  4 PCl3s


P4s  10Cl2g  4 PCl3s


c State two reasons why the deflagrating spoon with ridcover should be used


Chlorine in the gas jar is poisonoustoxic


Burning phosphorus produces poisonoustoxic phosphorus III chloride  phosphorus V chloride


Ensure the reaction is not affected by airoxygen from the atmosphere


d After the reaction is complete 2cm3 of distilled water were added The solution formed was tested with both blue and red litmus papers


i State the observations made


Blue litmus paper turns red


Red litmus paper remain red


ii Explain the observation made in di above


Phosphoric V Chloride hydrolyze in water to phosphoric V acid and produce hydrogen chloride gas Both hydrogen chloride and phosphoric V acid are acidic


Chemical equation


PCl5 l  4H2Ol  H3PO4 aq  5HClg


15 State and explain the observations made when gas jar containing chlorine is inverted over another containing hydrogen sulphide gas


Observation


Yellow solid formed


Pale colour of chlorine fades


Explanation


Chlorine oxidizes hydrogen sulphide to sulphur itself reduced to hydrogen chloride gas A little water catalyzes the reaction


H2Sg  Cl2g  Ss  HClg


yellow solid White Fume


16 Chlorine was bubbled in aqueous ammonia solution in a beaker state and explain the observation made


White fumes evolved


Pale green colour of chlorine fades


Chlorine reacts with ammonia gas to form a dense white fume of ammonia chloride and Nitrogen gas is produced


8NH3g  3Cl2g  6NH4Cls  N2g


17 a Dry gas was bubbled in cold dilute sodium hydroxide solution Explain the observations made


Pale yellow solution is formed


Chlorine reacts withhot concentrated sodiumsodium hydroxide  Potassium hydroxide solution to form pale yellow solution of metal chlorate V and chlorides of the metal


Chemical equation


Cl2g  2NaOH  NaClOaq  NaClaq  H2Ol


sodium hydroxide Sodium Chlorate I


Cl2g  2KOH  KClOaq  NaClaq  H2Ol


Potassium hydroxide Potassium Chlorate I


bThe experiment in 17a was repeated with hot concentrated sodium hydroxide solution Explain the observation made


Observation


Explanation


Chlorine reacts with hot concentrated Sodium hydroxidePotassium hydroxide solution to form pale yellow solution of metal chlorate v and chlorides of metals


3Cl2g  6NaOHaq  NaClO3 aq  5NaClaq  3H2Ol


Sodium hydroxide Sodium Chlorate V


3Cl2g  6KOHaq  KClO3 aq  5KClaq  3H2Ol


Potassium hydroxide Potassium Chlorate V


The products formed when chlorine reacts with alkalis depend thus on temperature and the concentration of alkalis


c i Write the equation for the formation of calcium chlorite I and calcium chlorate V


2Ca OH2aq  2Cl2g  CaCl2aq  CaOCl2aq  H2Ol


Calcium hydroxide Calcium ChlorateI


Colddilute


Ca OH2aq  Cl2g  CaCl2aq  CaClO32aq  H2Ol


Calcium ChlorateV


B THE HALOGENS


a What are halogens


These are elements in group VII of the periodic table They include


b Compare the atomic radius and ionic radius of chloride ion and chlorine Explain


The radius of chlorine is smaller than the ionic radius o the chloride ion


Effective nucleus attraction on outer energy level in chloride ion is less than chlorine atom because of extra gained electron gained electron that repelled thus causes the outer energy level to expandincrease


c Compare the atomic radius of chlorine and fluorine Explain


Atomic radius of Fluorine is smaller than that of chlorine


Chlorine has more energy levels than fluorine occupied by more electrons


d Chlorine is a gas Bromine is a liquid Iodine is a solid Explain the above observations


Bromine Chlorine and iodine exists as diatomic molecules bonded by strong covalent bond Each molecule is joined to the other by weak intermolecular forces Vanderwaals forces


The strength of intermolecularVanderwaals forces of attraction increase with increase in molecular sizeatomic radiusIodine has therefore the largest atomic radius and thus strongest intermolecular forces to make it a solid


e i What is electronegativity


Electronegativity is the tendencyease of acquiring gaining electrons by an element during chemical reaction


It is measured using Paulings scale


Fluorine with Pauling scale 40 is the most electronegative element in the periodic table and thus the highest tendency to acquiregain extra electron


ii The table below shows the electronegativity of the halogens


Explain the trend in electronegativity of the halogens


Decrease down the group from fluorine to Astatine


Atomic radius increase down the group decreasing electron  attracting power down the group from fluorine to astatine


f iWhat is electron affinity


Electron affinity is the energy required to gain an electron in an atom of an element in its gaseous state


ii Study the table below showing the election affinity of halogens for the process x  e  x


iii Explain the trend in electron affinity of the halogens


Decrease down the group


Atomic radius of halogens increase down the group thus incominggained electron is attracted less strongly by the progressively larger atoms with a decreasing effective nuclear charge on outer energy level


iv Which is a move stable ion Cl or Br  explain


Cl ion


Has a more negativeexothermic electron affinity than Br


v Differentiate between electron affinity and


I Ionization energy


Ionization energy is the energy required to lose donate an electron in an atom of an element in its gaseous state while electron affinity is the energy required to gainacquire extra electron by an atom of an element in its gaseous state


Both are measured in kilojoules per mole


II Electronegativity


Electron affinity is the energy required to gain an electron in an atom of an element in gaseous state It involves the process


Xg  e  Xg


Electronegativity is the easetendency of gaining acquiring electrons by an element during chemical reactions


It does not involve use of energy but theoretical arbitrary Paulings scale of measurements


g i 5cm3 of sodium chloride Sodium bromide and Sodium iodide solutions were put separately in test tubes 5 drops of chlorine water was added to each test tube state and explain the observation made


Observation


Yellow colour of chlorine water fades in all test tubes expect with sodium chloride


Coloured Solution formed


Explanation


Chlorine is more electronegative than bromine and iodine On adding chlorine water bromine and Iodine are displaced from their solutions by chlorine


ii The experiment in g i was repeated with 5 drops of bromine water instead of chlorine water explain the observation made


Yellow colour of bromine water fades in test tube containing sodium iodide


Brown solution formed in test tube containing sodium iodide


Bromine is more electronegative than iodide but less 6than chlorine


On adding Bromine water iodide displaced from its solution but not chlorine


iii Using the knowledge in gi and ii above


Complete the table below using X to show no reaction and  to show a reaction


Write an ionic equation for the reaction where there is V


F2 g 2Cl aq  2Faq  Cl2g


F2 g 2Br aq  2Faq  Br2aq


F2 g 2I aq  2Faq  I2aq


Cl2 g  2Br aq  2Claq  Br2aq


Cl2 g 2I aq  2Claq  I2aq


Br2 aq 2I aq  2Braq  I2aq


h State one uses of


Fluorine


Manufacture of PTFE Poly tetra fluoroethene synthetic fiber


Reduce tooth decay when added in small amountsequations in tooth paste


Note large small quantities of fluorine fluoride ions in water cause browning of teethflourosis


Hydrogen fluoride is used to engrave word pictures in glass


Bromine


Silver bromide is used to make light sensitive photographic paperfilms


Iodide


Iodine dissolved in alcohol is used as medicine to kill bacteria in skin cuts It is called tincture of iodine


The table below to show some compounds of halogens


j i Using dot  and Cross x to represent electrons show the bonding in chlorine molecule


Name the type of bond formed


Covalent


Below is the table showing the bond energy of four halogens


Bond Bond energy k J mole1


ClCl 242


BrBr 193


II 151


What do you understand by the term bond energy


Bond energy is the energy required to break form one mole of chemical bond


Explain the trend in bond Energy of the halogens above


Decrease down the group from chlorine to Iodine


Atomic radius increase down the group decreasing the energy required to break the covalent bonds between the larger atom with reduced effective nuclear charge an outer energy level that take part in bonding


k Some compounds of chlorine are in the table below the oxidation state of chlorine in each compound


Compound Oxidation state Name of compound


NaClO3 5 Sodium chlorate V


ClO2 4 Chloric IV oxide


KClO2 3 Potassium chlorate III


NaClO 1 Sodium Chlorite I


Cl2 0 Chlorine Molecule


NaCl 1 Sodium Chloride I


MgCl2 1 Magnesium Chloride I


C HYDROGEN CHLORIDE


Occurrence


Hydrogen Chloride does not occur free in the atmosphere or in nature


Preparation


Hydrogen chloride may be prepared in the school laboratory by reacting solid sodiumpotassium chloride crystals with concentrated sulphuric Vi acid as in the set up below


Properties of hydrogen chloride gasquestions


What precautions should be taken when handling concentrated sulphuric acid Explain


Wear protective clothinggloves to avoid accidental contact with skin


Concentrated sulphuric VI acid is highly corrosiveit causes painful wounds when in contact with skin


What method of gas collection is used Explain


Downward delivery upward displacement of water


Hydrogen chloride is denser than air


a Write the equation for the reaction that takes place


NaCls  H2SO4l  NaHSO4aq  HClg


KCls  H2SO4l  KHSO4aq  HClg


NaCl is commonly used because it is cheaper than KCl


b What property of concentrated sulphuric VI acid is used during the above reaction


is the least volatile mineral acid thus displace the more volatile hydrogen chloride from its salt KClNaCl


iWhat is the purpose of concentrated sulphuric VI acid


Drying agent  to dry the gas


ii What property of concentrated sulphuric VI acid is used during the above use


Is hygroscopic  absorbs water but do not form solution


iii Name another substance which can be used to dry chlorine gas


anhydrous Calcium chloride


silica gel


ivUsing a chemical equation explain why anhydrous calcium oxide cannot be used in flask B


Calcium oxide reacts with water moisture to form calcium hydroxide The calcium hydroxide formed reacts with chlorine to form calcium hypochlorite


Chemical equations


CaOs  2H2Ol  CaOH2aq  H2Ol


CaOH2aq  Cl2 g  CaOCl2aq  H2Ol


This reduces the amount of Chlorine produced


dBlue and red litmus papers were dipped in the hydrogen chloride prepared above The Procedure was repeated with dampwetmoist litmus papers Explain the differences in observations made


Dry blue litmus papers remain blue


Dry red litmus papers remain red


Dampmoistwet blue litmus papers turn red


Dampmoistwet red litmus paper turns red


Dry hydrogen chloride is a molecular compound that is joined by covalent bonds between the atoms The gas is polar thus dissolves in water and ionize completely to free H that are responsible to turning blue litmus paper red


Dry hydrogen chloride gas was bubbled in two separately beakers containing water and in methylbenzene


Classify the two solvents as either polar or nonpolar


Water  polar


Methylbenzene  nonpolar


ii State and explain the observations made in the beaker containing


iMethylbenzene


Colour of litmus solution remain


Hydrogen chloride is a molecular substance When dissolved in nonpolar solvent it does not dissociate  ionize to release H ions that changes the colour of litmus solution


iiWater


Colour of litmus solution change to red


Hydrogen chloride is a molecular substance When dissolved in polar solvent like water it dissociateionize to release H ions that changes litmus solution to red


iiiWhy should an inverted filter funnel be used to dissolve hydrogen chloride


The filter funnel is dipped just below the water surface to increase the surface area of dissolving the gas and prevent suck back


ivName the solution formed when hydrogen chloride dissolves in water


Hydrochloric acid


f Describe the test for presence of hydrogen chloride gas


Dip a glass rod in ammonia Bring it to the mouth of a gas jar containing a gas suspected to be hydrogen chloride


White fumes of ammonia chloride are formed


g Place 5cm3 of dilute hydrochloric acid into a four separate test tubes To separate test tube add zinc magnesium iron and copper metals State and explain the observations made


Observation


Effervescencebubblesfizzing in all cases except copper


Colourless solution formed with zinc and magnesium


Green solution formed with ion


Gas produced that extinguishes splint with explosion


Explanation


Metals above hydrogen in reactivity series react with hydrochloric and liberating hydrogen gas


Chemical Equation


Concentrated hydrochloric acid is a weak oxidizing agent than other concentrated acids ieSulphuric VI acid and nitric V acid that react with all metals even those lower in the reactivity series


h Place 5cm3 of dilute hydrochloric acid into five separate test tubes To separate test tubes add calcium carbonate silver carbonate copper carbonate iron II carbonate and Sodium hydrogen carbonate Explain the observations made


Effervescencebubblesfizzing vigorously except in silver carbonate and lead II carbonate that stop later


Colourless solution formed except with iron II carbonate and copper II carbonate


Green solution formed with iron II carbonate


Blue solution formed with copper II carbonate


Carbonates and hydrogen carbonate react with dilute hydrochloric acid to produce carbon IV oxide water and form chlorides


All chlorides formed are soluble Except Lead II Chloride soluble on heatingwarming and silver chloride


Chemical equation


CaCO3 s  2HClaq  CaCl2aq  H2Ol  CO2g


Colourless solution


Ag2CO3 s  2HClaq  AgCls  H2Ol  CO2g


CoatsCover Ag2CO3


CuCO3 s  2HClaq  CuCl2aq  H2Ol  CO2g


Blue Solution


FeCO3 s  2HClaq  FeCl2aq  H2Ol  CO2g


NaHCO3 s  HClaq  NaClaq  H2Ol  CO2g


Place 5cm3 of dilute sodium hydroxide Potassium hydroxide and aqueous ammonia solution into three separate test tubes Add one drop of phenolphthalein indicator drop wise add dilute hydrochloric acid Explain the observations made


Observation


Colour of Phenophthalein indicator change from pink to colourless


Explanation


Hydrochloric acid neutralizes alkalis to salt and water


When all the alkali has reacted with the acid An extra slight excess acid turns the indicator used to colourless


NaOHaq  HClaq  NaClaq  H2Ol


KOHaq  HClaq  KClaq  H2Ol


Chemical equation


NH4OHaq  HClaq  NHaClaq  H2Ol


j Place 5cm3 of hydrochloric acid into four separate test tube tubes Separately add about 1g of each of copper II Oxide Zinc II Oxide Lead II Oxide Calcium II Oxide What happens to each test tube Explain


All Solid dissolves except Lead II Oxide


Colourless solution formed with zinc Oxide and calcium II Oxide blue solution formed with copper II Oxide


Metal oxides dissolves in dilute hydrochloric acid to form water and chloride salt Insoluble Lead II chloride and silver chloride once formed covercoat unreacted oxides stopping further reaction


Chemical equation CuOs  HCl aq  CaCl2aq  H2Ol


Chemical equation CaOs  HCl aq  CaCl2 aq  H2O l


Chemical equation PbOs  2HCl aq  PbCl2 aq  H2O l


Chemical equation ZnOs  HCl aq  ZCl2 aq  H2O l


k Manufacture of Hydrochloric acid


i Raw Materials


1 Hydrogen


i During electrolysis of Brine from the flowing mercurycathode cell during the manufacture of sodium hydroxide solution


iiFrom water gas by passing steam in heated charcoal


Cs  H2O  COg  H2g


iiiFrom partial oxidation of natural gasmethane


CH4g  O2g  COg  3H2g


iFrom electrolysis of fusedsolid sodium chloride in the downs process during extraction of sodium


iiFrom electrolysis of brineconcentrated sodium chloride solution in the flowing mercurycathode during the manufacture of sodium hydroxide solution


iiChemical processes


Hydrogen and chlorine gases are separately passed through concentrated sulphuricVI acid to act as a drying agent


Small amount of pure hydrogen is continuously ignited in a chamber with continous supply of pure dry chlorine


Large amount of hydrogen explodes


Hydrogen burns in chlorine to form hydrogen chloride gas


Chemical Equation


H2g  Clg  2HClg


The hydrogen chloride produced is then passed up to meet a downward flow of water in the absorbtion chambers Hydrogen chloride is very soluble in water and dissolves to form 35 concentrated hydrochloric acid


HClg  aq  HClaq


The absorption chamber is shelved and packed with broken glass beads to


iSlow down the downward flow of water


iiIncrease surface area over which the water dissolves


The hydrochloric acid is then transported in steel tanks lined with rubber for market


iiiUses of Hydrochloric Acid


To standardize the pH of alcohol and wines


Regenerating ionexchange resin during removal of hardness of water


Pickling of metals to remove oside layers on their surfaces


In the manufacture of dyes and drugs


Making zinc chloride for making dry cells


ivDiagram Showing Industrial manufacture


iiEnvironmental effects of manufacturing HCl


Hydrochloric acid is acidic Any leakage from a manufacturing plant to nearby riverslake causes exess acidity that lowers pH of water killing marine life


Hydrogen chloride leakage into atmosphere dissolves to form acidic rain that accelerate corrosion in buildings Breathing problems to human beings and kill fauna and flora around the paint


Chlorine leakage causes breathing and sight problems to human being It accelerates bleaching of dyed metals


Hydrogen leakage can cause an explosion because impure hydrogen explodes on ignition


Factors considered in setting hydrochloric acid manufacturing plant


Nearness to the manufacturing of sodium hydroxide because the byproducts of electrolysis of brine are the raw materials for hydrochloric acid plant


Availability of natural gas for extraction of hydrogen


NearnessAvailability of water to dissolve the hydrogen chloride gas


Availability of labour market capital and good means of transport


D CHLORIDE Cl SALTS


Occurrence


Chlorides are salts derived from hydrochloric acid Hydrochloric acid is a monobasic HX salt with only one ionazablereplaceable H in its molecule All chlorides are therefore normal salts


All metals exist as chloride salt except platinum and gold as below


iBoth FeCl2 and FeCl3 exists but FeCl2 is readily oxidized to FeCl3 because it is more stable


iiPbCl2 and PbCl4 exist but PbCl4 is only oxidized to form PbCl2 by using excess chlorine It is less stable


iiiCuCl and CuCl2 exists but CuCl2 is thermodynamically more stable than CuCl CuCl disproportionate to Cu and CuCl2


ivHgCl and HgCl2exists as molecular compounds


All chlorides are solubledissolves in water except silver chlorideAgCl Copper I chloride CuCl Mercury I Chloride Hg2Cl2 and Lead II Chloride PbCl2 that dissolves in warm water


Most chlorides are very stable compounds They do not decompose on gentle or strong bunsen burner heating in a school laboratory except Ammonium Chloride


Heating ammonium chloride


Place about 2g of solid ammonium chloride crystals in a clean dry boiling tubeHeat gently then strongly


Observation


red litmus paper turn blue


blue litmus paper remains blue


Then later


both blue litmus papers turn red


Explanation


Ammonium chloride on heating decomposes through chemical sublimation to ammonia and hydrogen chloride gas Ammonia gas is less dense than hydrogen chloride It is a basic gas and diffuses out faster to turn red litmus paper to blue Hydrogen chloride is an acidic gas It is denser than ammonia gas and thus diffuses slower than ammonia gas to turn the already both blue litmus paper to red


Chemical equation


NH4Cls  HClg  NH3 g


acidic gas basicalkaline gas


Test for Cl ions


The following experiment shows the test for the presence of Cl ions in solids chloride salts


Procedure


Place about 1g of sodium chloride Zinc chloride and copper II chloride in separate boiling tubes Place moist blue and red litmus papers on the mouth of the test tube Carefully add three drops of concentrated sulphuric VI acid


Dip a glass rod in aqueous ammonia solution then bring it to the mouth of the boiling tube


bExplanation


Concentrated sulphuric VI acid is the less volatile mineral acid


It vigorously displaces chlorine in metal chlorides to evolve acidic hydrogen chloride gas fumes


NaCls  H2SO4l  NaHSO4aq  HClg


KCls  H2SO4l  KHSO4aq  HClg


CuCl2s  H2SO4l  CuSO4aq  2HClg


ZnCl2s  H2SO4l  ZnSO4aq  2HClg


Hydrogen chloride and ammonia gases react and form white fumes of ammonium chloride that confirms presence of Cl ions in the solid substance


NH3g  HClg  NH4Cls


The following experiment shows the test for the presence of Cl ions in solution aqueous chloride salts


iUsing aqueous Lead II nitrateV


aProcedure


IPlace about 5cm3 of sodium chloride Iron III chloride and copper II chloride in separate boiling tubes Add four drops of Lead II nitrateV solution to each Preserve


IITo the preserved sample add six drops of nitric V acid Preserve


III To the preserved sample heat the mixture to boil


Explanation


IWhen LeadII nitrateV solution is added to an unknown salt  a white precipitateppt of LeadII sulphateVI LeadII carbonateIV LeadII sulphateIV LeadII chlorideI are formed


Ionic equation


Pb2 aq  SO42aq  PbSO4s


Pb2 aq  SO32aq  PbSO3s


Pb2 aq  CO32aq  PbCO3s


Pb2 aq  Claq  PbCl2s


IIWhen the white precipitateppt formed is acidified with dilute nitricV acid the white precipitate of LeadII sulphateVI and LeadII chlorideI persistremain while that of LeadII carbonateIV and LeadII sulphateIV dissolves


IIIOn heating warming Lead II chloride I dissolves but on cooling it recrystallizesThis shows the presence of Cl ions in aqueous solutions


iiUsing aqueous silver I nitrateV


Procedure


I Place about 5cm3 of sodium chloride Iron III chloride and copper II chloride in separate boiling tubes Add four drops of silverI nitrateV solution to each Preserve


II To the preserved sample add six drops of nitric V acid Preserve


IWhen silverI nitrateV solution is added to an unknown salt  a white precipitate ppt of silverI carbonateIV and silverI chlorideI are formed


2Ag aq  CO32aq  Ag2CO3s


Ag aq  Claq  AgCls


II When the white precipitateppt formed is acidified with dilute nitric V acid the white precipitate of silver I chloride I persistremain This shows the presence of Clions in aqueous solutions


Silver I carbonate IV dissolves when reacted with nitric V acid


COMPREHENSIVE REVISION QUESTIONS


1 In an experiment dry hydrogen chloride gas was passed through heated zinc turnings as in the set up below The gas produced was the passed through copperII oxide


Write the equation for the reaction


iFor the school laboratory preparation of hydrogen chloride gas


NaCls  H2SO4l  NaHSO4aq  HClg


iiin tube S


Zns  2HClaq  ZnCl2aq  H2g


bState and explain the observation made in tube V


Observationscolour of solid changes from black to brown


colourless liquid forms on the cooler parts of tube V


ExplanationHydrogen produced in tube S reduces black copperII oxide to brown copper metal and the gas oxidized to water vapour that condense on cooler parts


Chemical equation


CuOs H2g Cus  H2Ol


cHow would the total mass of tube S and tube V and their contents compare before and after the experiment


Tube S Mass increaserise because Zinc combine with chlorine to form heavier Zinc Chloride


Tube V Mass decreasefallslowers because copper II oxide is reduced to lighter copper and oxygen combine with hydrogen to form water vapour that escape


2 Chlorine is prepared by using solid sodium chloride concentrated sulphuricVI acid and potassium manganateVII


aWhat is the role of the following in the reaction


i concentrated sulphuricVI


To produce hydrogen chloride gas by reacting with the solid sodium chloride


ii Potassium manganateVII


To oxidize hydrogen chloride gas to chlorine


3Use the flow chart below to answer the questions that follow


ai Name


gas X Hydrogen chloride


solution W hydrochloric acid


gas Q chlorine


bleaching agent Z sodium chlorateV


bWrite the chemical equation for the formation of


i gas X


NaCls  H2SO4l  NaHSO4aq  HClg


iisolution W


HClg  aq  HClaq


iiigas Q


2KMnO4  16HClaq  2KClaq  2MnCl2aq  8H2Ol  5Cl2g


ivbleaching agent Z


6NaOHaq  3Cl2g NaClaq  NaClO3aq  3H2Ol


cState and explain the following observations


i a glass rod dipped in aqueous ammonia is brought near gas X


Observation Dense white fumes


ExplanationAmmonia gas reacts with hydrogen chloride gas to form dense white fumes of ammonium chloride


Chemical equation NH3g HClg  NH4Cls


iiWet blue and red litmus papers were dipped into gas Q


Observations Blue litmus paper turned red the both are bleached


decolorized


Explanations chlorine reacts with water to form both acidic hydrochloric and chloric I acids that turn blue litmus paper red Unstable chloric I acid oxidizes the dye in the papers to colourless


Chemical equations


Cl2g  HClaq HClaq  HClOaq


Coloured dye HClOaq HClaq  Colourless dye O


Coloured dyeO  HClOaq HClaq  Colourless dye


4Use the flow chart below to answer the questions that follow


Name


Liquid A Concentrated sulphuricVI acid


Process Z Neutralization


White solid X Ammonium chloride


bWrite the equation for the formation of


i Hydrogen chloride


NaCls  H2SO4l  NaHSO4aq  HClg


ii B


HClg  aq  HClaq


iiiprocess Z using ionic equation


H aq  OHaq  H2Ol


ivC using ionic equation


Ag aq  Claq  AgCls


cDescribe how solution B is obtained


Bubbling hydrogen chloride gas through inverted funnel into distilled water until no more dissolve


5 The results obtained when halogens are bubbled into test tubes containing solutions of halide AB and C is as in the table below Tickv means a reaction took place Crossx means no reaction took place


aIdentify the halide ions represented by letter


A Cl


B I


C Br


bWrite the ionic equation for the reaction that take place with halide


i C


Cl2g  2Braq  2Claq  Br2aq


Cl2g  2Iaq  2Claq  I2aq


6The diagram below shows a set up of apparatus for the school laboratory collection of dry chlorine gas


aName


i Substance Q


Concentrated hydrochloric acid


ii Suitable drying agent L


Concentrated sulphuric VI acid


anhydrous calcium chloride


silica gel


b State a missing condition for the reaction to take place faster


HeatHeating


c Red and blue litmus papers were dipped into the chlorine gas from the above set up State and explain the observations made


Observation Blue litmus paper remains blue Red litmus paper remain red


Explanation Dry chlorine has no effect on dry litmus papers


d Write the equation for the reaction taking place in the conical flask


MnO4 s  4HClaq  MnCl2aq  2H2Ol  Cl2g


e Name two other substances that can be used in place of MnO2


LeadIV oxide PbO2


Potassium manganateVIKMnO4


Potassium dichromateK2Cr2O4


Bleaching powderCaOCl2


7 The set up below shows the apparatus used to prepare and collect anhydrous ironIII chloride


aName salt K


IronIIIcchloride


Write the equation for the reaction for the formation of salt K


2Fes  3Cl2 g  2FeCl3 sg


State and explain the following


iSmall amount of water is added to iron II chloride in a test tube then shaken


Solid dissolves to form a green solution IronII chloride is soluble in water


iiIThree drops of aqueous sodium hydroxide is added to aqueous ironII chloride and then added excess of the alkali


Observation


Green precipitate is formed that persistremain insoluble in excess akali


Explanation


IronII chloride reacts with aqueous sodium hydroxide to form a green precipitate of ironII hydroxide


Ionic equation


Fe2aq  OHaq  FeOH2s


IISix drops of hydrogen peroxide is added to the mixture in dii above


Effervescencebubblingfizzing take place and the green precipitate dissolve to form a yellowbrown solution


hydrogen peroxide oxidizes green Fe2to yellow brown Fe3solution


9Use the flow chart below to answer the questions that follow


a Write the chemical equation for the formation of gas A


NaCls  H2SO4l  NaHSO4aq  HClg


b Identify


i four possible ions that can produce white precipitate B


SO42SO32 CO32 Cl


iitwo possible ions that can produce


IWhite precipitate C


IIcolourless solution D


SO32 CO32


iiipossible ions present in


IWhite precipitate E


IIcolourless solution F


Cl


11 Below is a set up in the preparation of a particular salt Study it and answer the questions that follow


State the observation made when aluminium wool is heated


Glows red hot


bi Identify salt A


aluminiumIII chloride AlCl3


iiWrite the equation for the formation of salt A


2Als  3Cl2g  2AlCl3sg


iiiWhat property of salt A is exhibited as shown in the experiment


It sublimessublimation


ivCalculate the minimum volume of chlorine required to form 700kg of ironIII chloride at room temperatureFe 560 Cl355 1 mole of a gas 24000cm3 1000g  1kg


Mole ratio Fe  Cl2  2 3 molar mass FeCl3  1625g


Method 1


2 x 1625 g FeCl3  3x 22400 cm3 Cl2


700 x1000 gFeCl3  700 x1000 x3 x224002 x 1625


14474 x 108 cm3


Method 2


Moles of FeCl3 mass molar mass


700 x 1000  1625  43076923 moles


Moles of Cl2 32 moles of FeCl3


32 x 43076923  64615385 moles


Volume of chlorine moles x molar gas volume


64615385 x 24000  15508 x 108 cm3


c Name another metal that can produce similar results as salt K


Iron


di What is the purpose of anhydrous calcium chloride


ensure the apparatus are water free


prevent water from the atmosphere from entering and alteringhydrolysing salt A


ii Write the equation for the reaction that take place if anhydrous calcium chloride is not used in the above set up


AlCl3s  3H2Ol  AlOH3aq  3HClg


iii Write the equation for the reaction that take place when Iron metal is reacted with dry hydrogen chloride gas


Fes  2HClg  FeCl2s  H2g


ivCalculate the mass of IronIIchloride formed when 60cm3 of hydrogen chloride at rtp is completely reacted 1 mole of a gas 24dm3 at rtp Fe  56O Cl 355


Chemical equation Fes  2HClg  FeCl2s  Cl2g


Mole ratio HCl FeCl2  11


Molar mass FeCl2  127g


Moles of HCl used  60cm3 24000cm3  25 x 10 3 moles


Moles of FeCl2  Moles of HCl  25 x 10 3 moles


Mass of FeCl2  moles x molar mass  25 x 10 3 x 127 03175g


12Study the flow chart below and use it to answer the questions that follow


aIdentify substance


P IronII chlorideFeCl2


Q Chlorine  Cl2


R IronIII chlorideFeCl3


bWrite the equation for the reaction for the formation of


i gas Q


2KMnO4 s  16HClaq  2KClaq  2MnCl2aq  8H2Ol  5Cl2g


ii the green precipitate using ionic equation


Ionic equation


Fe2aq  2OHaq  FeOH2s


ii the brown precipitate using ionic equation


Fe3aq  3OHaq  FeOH3s


cA glass rod was dipped in aqueous ammonia The rod was then brought near hydrogen chloride State and explain the observation made


Observation


White fumes


Explanation


Ammonia gas reacts with hydrogen chloride gas to form white fumes of ammonium chloride


Chemical equation


NH3g  HClg  NH4Cls


13 Using dotand crossxto represent electronsshow the bonding in aluminium chloride in vapour phase


bHow many electrons in


ialuminium atoms are used in bonding


Six electronsthree valence electrons in each aluminium atom


iichlorine atoms atoms are used in dativebonding


four electronstwo lone pairs of valence electrons in two chlorine atoms


iiithe molecule are used in bonding


Sixteen electrons


six valence electrons from aluminium atom through covalent bond


six valence electrons from chlorine atoms through covalent bond


four valence electrons from chlorine atoms through dative bond


cHow many lone pair of electrons do not take part in bonding within the molecule


Sixteen16 lone pairs from six chlorine atoms32 electrons


dAluminium chloride does not conduct electricity in molten state but Magnesium chloride conduct


Aluminium chloride is a molecular compound that has no free mobile Al3 and Cl ions which are responsible for conducting electricity Magnesium chloride has free mobile Mg2 and Cl ions because it is an ionic compound


8 Use the flow chart below to answer the questions that follow


aWrite an equation for the school laboratory formation of hydrogen chloride gas


NaCls  H2SO4l  NaHSO4aq  HClg


KCls  H2SO4l  KHSO4aq  HClg


bName


I solid Y Iron II chloride FeCl2


II green precipitateIron II hydroxide Fe OH2


III Gas Y Chlorine Cl2


IV Bleaching agent A Sodium hypochlorite NaOCl


cBlue and red litmus papers were dipped into bleaching agent A Write the equation for the reaction that takes place


Coloured dye NaOClaq NaClaq  Colourless dye  O


Coloured dyeO  NaOClaq NaClaq  Colourless dye


dState four uses of gas Z


Bleaching agent


Manufacture of hydrochloric acid


Chlorination of water to kill germs


Manufacture of PVC pipes


CHEMISTRY OF NITROGEN


ANITROGEN


a Occurrence


Nitrogen is found in the atmosphere occupying about 78 by volume of air


Proteins amino acids polypeptides in living things contain nitrogen


b Isolation of nitrogen from the air


Nitrogen can be isolated from other gases present in air like oxygen water vapour carbon IV oxide and noble gases as in the school laboratory as in the flow chart below


Water is added slowly into an empty flask which forces the air out into another flask containing concentrated sulphuric VI acid Concentrated sulphuric VI acid is hygroscopic It therefore absorbremove water present in the air sample


More water forces the air into the flask containing either concentrated sodium hydroxide or potassium hydroxide solution These alkalis react with carbon IV oxide to form the carbonates and thus absorbsremove carbon IV oxide present in the air sample


Chemical equation 2NaOH aq  CO2 g  Na2CO3 aq  H2Ol


Chemical equation 2KOH aq  CO2 g  K2CO3 aq  H2Ol


More water forces the air through a glass tube packed with copper turnings Heated brown copper turnings react with oxygen to form black copper II oxide


Chemical equation 2Cu s  O2 g  CuO s


brown black


The remaining gas mixture is collected by upward deliverydownward displacement of waterover water It contains about 99 nitrogen and 1 noble gases


On a large scale for industrial purposes nitrogen is got from fractional distillation of air


c Nitrogen from fractional distillation of air


For commercial purposes nitrogen is got from the fractional of air


Air is first passed through a dust precipitatorfilter to remove dust particles


The air is then bubbled through either concentrated sodium hydroxide or potassium hydroxide solution to removeabsorb CarbonIV oxide gas


Air mixture is the cooled to 25oCAt this temperature water vapour  liquidifies and then solidify to ice and thus removed


The air is further cooled to 200oC during which it forms a blue liquid


The liquid is then heated Nitrogen with a boiling point of 196oC distils first then Argon at186oC and then finally Oxygen at 183oC boils last


c School laboratory preparation of Nitrogen


The diagram below shows the set up of the school laboratory preparation of nitrogen gas


dProperties of Nitrogen gasQuestions


1Write the equation for the reaction for the school laboratory preparation of nitrogen gas


Chemical equation NH4Cl s  NaNO2sNaCl g NH4NO2 s


Chemical equation NH4NO2 s  N2 g  H2O l


2 State three physical properties of nitrogen gas


colourless odourless less dense than air neutral and slightly soluble in water


3 State and explain the observation made when a burning magnesium ribbon is lowered in a gas jar containing nitrogen gas


Observation It continues burning with a blight blindening flame forming white ash


Explanation


Magnesium burns to produce enough heat energy to reacts with nitrogen to form white magnesium nitride


Chemical equation3Mg s  N2 g  Mg3N2 s


white ashsolid


4 State two main uses of nitrogen gas


manufacture of ammonia from Haber process


As a refrigerant in storage of semen for Artificial insemination


B OXIDES OF NITROGEN


Nitrogen forms three main oxides


iNitrogenI oxideN2O


ii NitrogenII oxide NO


iii Nitrogen IV oxide NO2


i Nitrogen I oxideN2O


a Occurrence


Nitrogen I oxide does not occur naturally but prepared in a laboratory


bPreparation


The set up below shows the set up of apparatus that can be used to prepare Nitrogen I oxide in a school laboratory


c Properties of nitrogen I oxide Questions


1 Write the equation for the reaction for the school laboratory preparation of Nitrogen I oxide


Chemical equation NH4NO2s  H2O l  N2O g


2a State and explain three errors made in the above set up


Oxygen is being generated instead of Nitrogen I oxide


Ammonium NitrateV should be used instead of potassium manganateVI and manganeseIVoxide


b State three physical properties of Nitrogen I oxide


slightly soluble in water


colourless


odourless


less dense than air


slightly sweet smell


3 State and explain the observation made when a burning magnesium ribbon is lowered in a gas jar containing Nitrogen I oxide


Observation  Continues to burn with a bright flame


White solidresidue is formed


ExplanationMagnesium burns in air to produce enough heatenergy splitbreak Nitrogen I oxide gas into free Nitrogen and oxygen then continues to burn in oxygen to form white solidash of Magnesium oxide


Chemical equation


Mgs  N2O g MgO s  N2g


4 State and explain the observation made when the following non metals are burnt then lowered in a gas jar containing Nitrogen I oxide


a Carboncharcoal


Observation  Continues to burn with an orange glow


colorless gas is formed that forms white precipitate with lime water


ExplanationCarboncharcoal burns in air to produce enough heatenergy splitbreak Nitrogen I oxide gas into free Nitrogen and oxygen then continues to burn in oxygen to form carbon IV oxide gas Carbon IV oxide gas reacts to form a white precipitate with lime water


Chemical equation Cs  2N2O g CO2 g  2N2g


b Sulphur powder


Observation  Continues to burn with a blue flame


colorless gas is formed that turn orange acidified potassium dichromate VI to green


ExplanationSulphur burns in air to produce enough heatenergy splitbreak Nitrogen I oxide gas into free Nitrogen and oxygen then continues to burn in oxygen to form sulphur IV oxide gas Sulphur IV oxide gas turns orange acidified potassium dichromate VI to green


Chemical equation Ss  2N2O g SO2 g  2N2g


5 State two uses of nitrogen I oxide


As laughing gas because as anesthesia the patient regain consciousness laughing hysterically after surgery


improves engine efficiency


6 State three differences between nitrogen I oxide and oxygen


Oxygen is odourless while nitrogen I oxide has faint sweet smell


Both relightrekindle a glowing wooden splint but Oxygen can relight a feeble glowing splint while nitrogen I oxide relights well lit splint


Both are slightly soluble in water but nitrogen I oxide is more soluble


ii Nitrogen II oxide NO


a Occurrence


Nitrogen II oxide does not occur naturally but prepared in a laboratory


bPreparation


The set up below shows the set up of apparatus that can be used to prepare Nitrogen II oxide in a school laboratory


c Properties of nitrogen II oxide Questions


Write the equation for the reaction for the school laboratory preparation of Nitrogen II oxide


Chemical equation 3Cus  8HNO3aq  4H2O l2NO g 2CuNO32aq


Chemical equation 3Zns  8HNO3aq  4H2O l2NO g 2ZnNO32aq


Chemical equation 3Mgs  8HNO3aq  4H2O l2NO g2MgNO32aq


2 State three physical properties of Nitrogen II oxide


insoluble in water


colourless


odourless


denser dense than air


has no effect on both blue and red litmus papers


State and explain the observation made when a burning magnesium ribbon is lowered in a gas jar containing Nitrogen II oxide


Observation  Continues to burn with a bright flame


White solidresidue is formed


ExplanationMagnesium burns in air to produce enough heatenergy splitbreak Nitrogen II oxide gas into free Nitrogen and oxygen then continues to burn in oxygen to form white solidash of Magnesium oxide


Chemical equation 2Mgs  2NO g 2MgO s  N2g


State and explain the observation made when the following non metals are burnt then lowered in a gas jar containing Nitrogen II oxide


a Carboncharcoal


Observation  Continues to burn with an orange glow


colorless gas is formed that forms white precipitate with lime water


ExplanationCarboncharcoal burns in air to produce enough heatenergy splitbreak Nitrogen II oxide gas into free Nitrogen and oxygen then continues to burn in oxygen to form carbon IV oxide gasCarbon IV oxide gas reacts to form a white precipitate with lime water


Chemical equation Cs  2NO g CO2 g  N2g


b Sulphur powder


Observation  Continues to burn with a blue flame


colorless gas is formed that turn orange acidified potassium dichromate VI to green


ExplanationSulphur burns in air to produce enough heatenergy splitbreak Nitrogen II oxide gas into free Nitrogen and oxygen then continues to burn in oxygen to form sulphur IV oxide gasSulphur IV oxide gas turns orange acidified potassium dichromate VI to green


Chemical equation Ss  N2O g SO2 g  N2g


c Phosphorus


Observation  Continues to produce dense white fumes


ExplanationPhosphorus burns in air to produce enough heatenergy splitbreak Nitrogen II oxide gas into free Nitrogen and oxygen then continues to burn in oxygen to form dense white fumes of phosphorus V oxide gas


Chemical equation 4Ps  10NO g 2P2O5g  5N2g


5 State one use of nitrogen II oxide


As an intermediate gas in the Ostwalds process for manufacture of nitricV gas


6 State and explain the observation made when nitrogen II oxide is exposed to the atmosphere


Observationbrown fumes producedevolved that turn blue litmus paper red


Explanation Nitrogen II oxide gas on exposure to air is quickly oxidized by the air oxygen to brown nitrogen IV oxide gas Nitrogen IV oxide gas is an acidic gas


Chemical equation 2NO g O2g 2NO2 g


colorless brown


ii Nitrogen IV oxide NO2


a Occurrence


Nitrogen IV oxide occurs naturally from active volcanic areas


formed from incomplete combustion of the internal combustion engine of motor vehicle exhaust fumes


from lightening


bPreparation


The set up below shows the set up of apparatus that can be used to prepare Nitrogen IV oxide in a school laboratory


c Properties of nitrogen IVoxide Questions


1 Write the equation for the reaction for the school laboratory preparation of Nitrogen II oxide


Chemical equation Cus  4HNO3aq  2H2O l2NO 2g CuNO32aq


Chemical equation Zns  4HNO3aq  2H2O l2NO 2g ZnNO32aq


Chemical equation Fes  4HNO3aq  2H2O l2NO 2g FeNO32aq


2 State three physical properties of Nitrogen IV oxide


solubledissolves in water


brown in colour


has pungent irritating poisonous odoursmell


denser dense than air


turns blue litmus papers to red


3 State and explain the observation made when Nitrogen IV oxidegas is bubbled in water


ObservationThe gas dissolves and thus brown colour of the gas fades


A colourless solution is formed


solution formed turns blue litmus papers to red


solution formed has no effect on red


ExplanationMagnesium burns in air to produce enough heatenergy splitbreak Nitrogen IV oxide gas dissolves then react with water to form an acidic mixture of nitricV acid andnitricIII acid


Chemical equationH2O l  2NO 2gHNO3aq  HNO2aq


nitricV acid nitricIII acid


4 State and explain the observation made when a test tube containing Nitrogen IV oxide is cooled then heated gently then strongly


Observation on cooling


Brown colour fades


Yellow liquid formed


Observation on gentle heating


Brown colour reappears


Yellow liquid formed changes to brown fumesgas


brown fumesgas changes to a colourless gas


ExplanationBrown nitrogen IV oxide gas easily liquefies to yellow dinitrogen tetraoxide liquidWhen the yellow dinitrogen tetraoxide liquid is gently heated it changes back to the brown nitrogen IV oxidegasWhen the brown nitrogen IV oxide gas is strongly heated it decomposes to colourless mixture of Nitrogen II oxide gas and Oxygen


Chemical equation O2s  2NO g  2NO2 g  N2O4l


colourless gases brown gas yellow liquid


5 State and explain the observation made when a burning magnesium ribbon is lowered in a gas jar containing Nitrogen IV oxide


Observation  Continues to burn with a bright flame


White solidresidue is formed


Brown fumescolour fades


ExplanationMagnesium burns in air to produce enough heatenergy splitbreak brown Nitrogen IV oxide gas into free colourless Nitrogen and oxygen then continues to burn in oxygen to form white solidash of Magnesium oxide


Chemical equation 4Mgs  2NO 2g 4MgO s  N2g


4 State and explain the observation made when the following non metals are burnt then lowered in a gas jar containing Nitrogen IV oxide


a Carboncharcoal


Observation  Continues to burn with an orange glow


colorless gas is formed that forms white precipitate with lime water


ExplanationCarboncharcoal burns in air to produce enough heatenergy splitbreak brown Nitrogen IV oxide gas into free colourless Nitrogen and oxygen then continues to burn in oxygen to form carbon IV oxide gasCarbon IV oxide gas reacts to form a white precipitate with lime water


Chemical equation2Cs  2NO 2g 2CO2 g  N2g


b sulphur powder


Observation  Continues to burn with a blue flame


colorless gas is formed that turn orange acidified potassium dichromate VI to green


ExplanationSulphur burns in air to produce enough heatenergy splitbreak brown Nitrogen IV oxide gas into free colourless Nitrogen and oxygen then continues to burn in oxygen to form sulphur IV oxide gasSulphur IV oxide gas turns orange acidified potassium dichromate VI to green


Chemical equation2Ss  2NO2 g 2SO2 g  N2g


c Phosphorus


Observation Continues to produce dense white fumes


ExplanationPhosphorus burns in air to produce enough heatenergy splitbreak brown Nitrogen IV oxide gas into free colourless Nitrogen and oxygen then continues to burn in oxygen to form dense white fumes of phosphorus V oxide gas


Chemical equation 8Ps  10NO2 g 4P2O5g  5N2g


5 State two uses of nitrogen IV oxide


In theOstwald process for industrial manufacture of nitric V gas


In the manufacture of TNT explosives


6 State and explain the observation made when nitrogen II oxide is exposed to the atmosphere


Observationbrown fumes producedevolved that turn blue litmus paper red


Explanation Nitrogen II oxide gas on exposure to air is quickly oxidized by the air oxygen to brown nitrogen IV oxide gas Nitrogen IV oxide gas is an acidic gas


Chemical equation 2NO g  O2g  2NO2 g


colourless brown


C AMMONIA NH3


Ammonia is a compound of nitrogen and hydrogen only It is therefore a hydride of nitrogen


a Occurrence


Ammonia gas occurs naturally from urine of mammals and excretion of birds


formed in the kidney of human beings


bPreparation


The set up below shows the set up of apparatus that can be used to prepare dry Ammonia gas in a school laboratory


Set up method 1


1 Write the equation for the reaction taking place in


Method 1


Chemical equation


Ca OH2s  NH4 ClsCaCl2 aq  H2Ol  2NH3g


bMethod 2


NaOH aq  NH4 Claq  NaCl aq  H2Ol  NH3g


2 State three physical properties of ammonia


has a pungent choking smell of urine


Colourless


Less dense than air hence collected by upward delivery


Turns blue litmus paper blue thus is the only naturally occurring basic gas at this level


3 Calcium oxide is used as the drying agent Explain why calcium chloride and concentrated sulphuricVI acid cannot be used to dry the gas


Calcium chloride reacts with ammonia forming the complex compound CaCl28H2O


Chemical equation CaCl2 s  8NH3g  CaCl2 8NH3g


Concentrated sulphuricVI acid reacts with ammonia forming ammonium sulphateVI salt compound


Chemical equation 2NH3g H2SO4l NH42SO4aq


4 Describe the test for the presence of ammonia gas


Using litmus paper


Dip moistdampwet blue and red litmus papers in a gas jar containing a gas suspected to be ammoniaThe blue litmus paper remain blue and the red litmus paper turns blueAmmonia is the only basic gasAt this level


Using hydrogen chloride gas


Dip a glass rod in concentrated hydrochloric acid Bring the glass rod near the mouth of a gas jar suspected to be ammonia White fumes of ammonium chlorideare producedevolved


5 Describe the fountain experiment to show the solubility of ammonia


Ammonia is very soluble in water


When a drop of water is introduced into flask containing ammonia it dissolves all the ammonia in the flask If water is subsequently allowed into the flask through a small inlet atmospheric pressure forces it very fast to occupy the vacuum forming a fountain If the water contains threefew drops of litmus solution the litmus solution turns blue because ammonia is an alkalinebasic gas If the water contains threefew drops of phenolphthalein indicator the indicator turns pink because ammonia is an alkalinebasic gas SulphurIVoxide and hydrogen chloride gas are also capable of the fountain experiment  If the water contains threefew drops of phenolphthalein indicator the indicator turns colourless because both SulphurIV oxide and hydrogen chloride gas are acidic gases


6 State and explain the observation made when hot platinum nichrome wire is placed over concentrated ammonia solution with Oxygen gas bubbled into the mixture


Observations


Hot platinum nichrome wire continues to glow red hot


Brown fumes of a gas are produced


Explanation


Ammonia reacts with Oxygen on the surface of the wire This reaction is exothermic producing a lot of heatenergy that enables platinum wire to glow red hot Ammonia is oxidized to NitrogenIIoxide gas and water Hot platinum nichrome wire acts as catalyst to speed up the reaction NitrogenIIoxide gas is further oxidized to brown NitrogenIVoxide gas on exposure to air


Chemical equation


i4NH3g  5O2g Pt 4NOg  6H2Ol


ii2NOg  O2g  2NO2g


7 Ammonia gas was ignited in air enriched with Oxygen gas State and explain the observations made


Ammonia gas burns with a green flame


Colourless gas produced


Ammonia gas burns with a green flame in air enriched with Oxygen to from Nitrogen gas and water


2NH3g  O2g  N2g  3H2Ol


8 Dry ammonia was passed through heated copperIIOxide as in the set up below


aState the observations made in tube K


Colour changes from black to brown


Colourless liquid droplet form on the cooler parts of tube K


biIdentify liquid L


Water H2Ol


iiExplain a chemical and physical test that can be used to identify liquid L


Chemical test


i Add threefew drops of liquid L into anhydrous copperIIsulphateVI


Colour changes from white to blue


ExplanationWater changes white anhydrous copperIIsulphateVI to blue hydrated copperIIsulphateVI


ii Add threefew drops of liquid L into anhydrous cobaltIIChloride


Colour changes from blue to pink


ExplanationWater changes blue anhydrous cobaltIIChloride to pink hydrated cobaltIIChloride


Physical test


iHeat the liquid It boils at 100oC at sea level 1atmosphere pressure760mmHg pressure 101300Pa101300Nm2


iiCool the liquid It freezes at 00oC


iiiDetermine the density It is 10gcm3


cWrite the equation for the reaction that take place


2NH3g  3CuOs  N2g  3H2Ol  3Cus


black brown


2NH3g  3PbOs  N2g  3H2Ol  3Pbs


brown when hot grey


8aWhat is aqueous ammonia


Aqueous ammonia is formed when ammonia gas is dissolved in water


NH3g  aq  NH3aq


A little NH3aq reacts with ammonia water to form ammonia solutionNH4OH


NH3 aq  H2Ol OHaq  NH4aq


This makes a solution of aqueous ammonia is a weak base alkali unlike other two alkalis


9Using dot and cross to represent outer electrons show the bonding in


a NH3


b NH4


10Name four uses of ammonia


iIn the manufacture of nitrogenous fertilizers


ii In the manufacture of nitricVacid from Ostwalds process


iiiAs a refrigerant in ships and warehouses


ivIn softening hard water


vIn the solvay process for the manufacture of sodium carbonate


viIn the removal of grease and stains


11aCalculate the percentage of Nitrogen in the following fertilizers


i NH42SO4


Molar mass of NH42SO4  132g


Mass of N in NH42SO4 28g


of N  28 x 100  212121


ii NH43PO4


Molar mass of NH43PO4  149g


Mass of N in NH43PO4 42g


of N  42 x 100  281879


bState two advantages of fertilizer a i over a ii above


iHas higher  of Nitrogen


iiHas phosphorus which is necessary for plant growth


c Calculate the mass of Nitrogen in a 50kg bag of


of N in NH42SO4  212121


Mass of N in 50 kg NH42SO4 212121 x 50  106 kg


ii NH4NO3


Molar mass of NH4NO3  80g


Mass of N in NH43PO4 28g


of N  28 x 100  35


of N in NH4NO3  35


Mass of N in 50 kg NH42SO4 35 x 50  175 kg


NH4NO3 therefore has a higher mass of Nitrogen than NH42SO4


dManufacture of Ammonia Haber process


Most of the Ammonia produced for industrial purposes uses the Haber process developed by the German Scientist Fitz Haber


iRaw materials


The raw materials include


iNitrogen from Fractional distillation of air from the atmosphere


iiHydrogen from


I Water gaspassing steam through heated charcoal


Cs  H2Ol  COg  H2 g


II Passing natural gas methane through steam


CH4g H2Ol  COg  3H2 g


iiChemical process


Hydrogen and Nitrogen are passed through a purifier to remove unwanted gases like CarbonIVoxideOxygensulphurIVoxide dust smoke which would poison the catalyst


Hydrogen and Nitrogen are then mixed in the ratio of 31 respectively The mixture is compressed to 200250atmoshere pressure to liquidify The liquid mixture is then heated to 400 450oCThe hot compressed gases are then passed over finely divided Iron catalyst promotedimpregnated with Al2O3 K2O Promoters increase the efficiency of the catalyst


Optimum conditions in Haber processs


Chemical equation


N2 g  3H2 g FePt 2NH3 g H  92kJ


EquilibriumReaction rate considerations


iRemoving ammonia gas once formed shift the equilibrium forward to the right to replace the ammonia Morehigher yield of ammonia is attained


iiIncrease in pressure shift the equilibrium forward to the right where there is less volumemolecules Morehigher yield of ammonia is attained Very high pressures raise the cost of production because they are expensive to produce and maintain An optimum pressure of about 200atmospheres is normally used


iiiIncrease in temperature shift the equilibrium backward to the left because the reaction is exothermic H  92kJ  Ammonia formed decomposes back to Nitrogen and Hydrogen to remove excess heat therefore a less yield of ammonia is attained Very low temperature decreases the collision frequency of Nitrogen and Hydrogen and thus the rate of reaction too slow and uneconomical


An optimum temperature of about 450oC is normally used


ivIron and platinum can be used as catalyst Platinum is a better catalyst but more expensive and easily poisoned by impurities than Iron Iron is promoted impregnated with AluminiumOxideAl2O3 to increase its surface areaarea of contact with reactants and thus efficiency The catalyst does not increase the yield of ammonia but it speed up its rate of formation


e NitricVacid HNO3


aIntroduction


NitricVacid is one of the mineral acids There are three mineral acids NitricVacid sulphuricVIacid and hydrochloric acid Mineral acids do not occur naturally but are prepared in a school laboratory and manufactured at industrial level


b School laboratory preparation


NitricVacid is prepared in a school laboratory from the reaction of Concentrated sulphuricVIacid and potassium nitrateV below


cProperties of Concentrated Nitric VacidQuestions


1Write an equation for the school laboratory preparation of nitricVacid


KNO3s  H2SO4l  KHSO4s  HNO3l


2Sodium nitrateVcan also be used to prepare nitricVacid State two reasons why potassium nitrateV is preferred over Sodium nitrateV


i Potassium nitrateV is more volatile than sodium nitrateV and therefore readily displaced from the less volatile concentrated sulphuricVIacid


ii Sodium nitrateV is hygroscopic and thus absorb water  Concentrated sulphuricVIacid dissolves in water The dissolution is a highly exothermic process


3 An all glass apparatus retort is used during the preparation of nitricV acid Explain


Hot concentrated nitricV acid vapour is highly corrosive and attacks rubber cork apparatus if used


4 Concentrated nitricV acid is colourless  Explain why the prepared sample in the school laboratory appears yellow


Hot concentrated nitricV acid decomposes to brown nitrogenIVoxide and Oxygen gases


4HNO3lg  4NO2g  H2O l O2g


Once formed the brown nitrogenIVoxide dissolves in the acid forming a yellow solution


5 State and explain the observation made when concentrated nitric V acid is heated


Observation


Brown fumes are produced


Colourless gas that relightsrekindles glowing splint


Explanation


Hot concentrated nitricV acid decomposes to water brown nitrogenIVoxide and Oxygen gases Oxygen gas is not visible in the brown fumes of nitrogen IV oxide


4HNO3g  4NO2g  H2O l O2g


6 Explain the observations made when


a About 2cm3 of IronIIsulphateVI solution is added about 5 drops of concentrated nitricV acid and the mixture then heatedwarmed in a test tube


iColour changes from green to brown


iibrown fumes gas produced on the upper parts of the test tube


Concentrated nitricV acid is a powerfulstrong oxidizing agent It oxidizes green Fe2 ions in FeSO4 to brownyellow Fe3 The acid is reduced to colourless NitrogenIIoxide


Chemical equation


6FeSO4aq  3H2SO4 aq  2HNO3aq  3Fe2SO4 3 aq 4H2O  2NOg


Colourless NitrogenIIoxide is rapidly further oxidized to brown NitrogenIVoxide by atmospheric oxygen


2NOg  Og  2NO2 g


colourless brown


b A spatula full of sulphur powder in a clean dry beaker was added to 10cm3 concentrated nitric V acid and then heated gentlywarmed


Observation


iYellow colour of sulphur fades


ii Brown fumes gas produced


Explanation


Concentrated nitricV acid is a powerfulstrong oxidizing agent It oxidizes yellow sulphur to colourless concentrated sulphuricVIacid The acid is reduced to brown NitrogenIVoxide gas


Ss  6HNO3l  4NO2g  H2O l H2SO4l


c A fewabout 10g pieces of copper turningsZinc granules Magnesium ribbon are added 10cm3 of concentrated nitricV acid in a beaker


i Brown fumes gas produced


ii Blue solution formed with copper turnings


iii Colourless solution formed with Zinc granulesMagnesium ribbon


Concentrated nitric V acid is a powerfulstrong oxidizing agent It oxidizes metals to their metal nitrate VI salts The acid is reduced to brown Nitrogen IV oxide gas


Chemical equation


Cus  4HNO3l  2NO2g  H2O l  CuNO3 2 aq


Zns  4HNO3l  2NO2g  H2O l  ZnNO3 2 aq


Mgs  4HNO3l  2NO2g  H2O l  MgNO3 2 aq


Pbs  4HNO3l  2NO2g  H2O l  PbNO3 2 aq


Ags  2HNO3l  NO2g  H2O l  AgNO3 aq


dProperties of Dilute Nitric VacidQuestions


iWhat is dilute nitricvacid


When concentrated nitricvacid is added to over half portion of water it is relatively said to be dilute A dilute solution is one which has more solventwater than soluteacid The number of moles of the acid are present in a large amountvolume of the solventThis makes the molarity number of moles present in one cubic decimeter of the solution to be low eg 002M


If more water is added to the acid until the acid is too dilute to be diluted further then an infinite dilute solution if formed


ii1cm length of polished Magnesium ribbon was put is a test tube containing 02M dilute nitricvacid State and explain the observation made


Observation


Effervescencebubblingfizzing


Colourless gas produced that extinguish burning splint with an explosionpop sound


Colourless solution formed


Magnesium ribbon dissolvesdecrease in size


Explanation


Dilute dilute nitricvacid reacts with Magnesium to form hydrogen gas


Mgs  2HNO3aq  H2 g  MgNO3 2 aq


With other reactive heavy metals the hydrogen gas produced is rapidly oxidized to water


Chemical equation 3Pbs  8HNO3aq  4H2O l2NO g 2PbNO32aq


Chemical equation 3Zns  8HNO3aq  4H2O l2NO g 2ZnNO32aq


Chemical equation 3Fes  8HNO3aq  4H2O l2NO g 2FeNO32aq


Hydrogen gas therefore is usually not prepared in a school laboratory using dilute nitric vacid


iiiA half spatula full of sodium hydrogen carbonate and CopperII carbonate were separately to separate test tubes containing 10cm3 of 02M dilute nitric V acid


Colourless gas produced that forms a white precipitate with lime water


Colourless solution formed with sodium hydrogen carbonate


Blue solution formed with CopperII carbonate


Dilute dilute nitric vacid reacts with Carbonates and hydrogen carbonates to form CarbonIVoxide water and nitrateVsalt


CuCO3 s  2HNO3aq  H2O l  CuNO3 2 aq  CO2 g


ZnCO3 s  2HNO3aq  H2O l  ZnNO3 2 aq  CO2 g


CaCO3 s  2HNO3aq  H2O l  CaNO3 2 aq  CO2 g


PbCO3 s  2HNO3aq  H2O l  PbNO3 2 aq  CO2 g


FeCO3 s  2HNO3aq  H2O l  FeNO3 2 aq  CO2 g


NaHCO3 s  HNO3aq  H2O l  NaNO3 aq  CO2 g


KHCO3 s  HNO3aq  H2O l  KNO3 aq  CO2 g


NH4HCO3 aq  HNO3aq  H2O l  NH4NO3 aq  CO2 g


CaHCO3 2 aq  2HNO3aq  2H2O l  CaNO3 2 aq  2CO2 g


MgHCO3 2 aq  2HNO3aq  2H2O l  MgNO3 2 aq  2CO2 g


iii 250cm3 of 01M NitricV acid was titrated with excess 02M sodium hydroxide solution using phenolphthalein indicator


I State the colour change at the end point


Colourless


II What was the pH of the solution at the end point Explain


pH 123


A little of the acid when added to the base changes the colour of the indicator to show the end point The end point therefore is acidic with low pH of NitricV acid NitricV acid is a strong acid with pH 123


III Calculate the number of moles of acid used


Number of moles  molarity x volume  01 x 25  25 x 103moles


1000 1000


IV Calculate the volume of sodium hydroxide used


Volume of sodium hydroxide in cm3


1000 x Number of moles  1000x 25 x 103  125cm3


Molarity 02


eIndustrial large scale manufacture of Nitric V acid


iRaw materials


1 AirOxygen


Oxygen is got from fractional distillation of air


Ammonia from Haber process


2 Chemical processes