H3C CHCH2  HI H3C CHI  CH3


Propene  Chlorine 2chloropropane


H H H H H H


H C C  C  H  Cl H  C  C  C H


H H H Cl H


3 Both But1ene and But2ene reacts with hydrogen bromide to form 2 bromobutane


Chemical equation


But1ene  hydrogen bromide 2bromobutane


H3C CH2 CHCH2  HBr H3C CH2CHBr CH3


H H H H H H H H


H C C  C  C  H  Br H  C C  C  C H


H H H H H Br H


But2ene  Hydrogen bromide 2bromobutane


H3C CH CHCH2  HBr H3C CHBrCH2  CH3


H C C  C  C H  Br  H H  C C  C  C H


H H H Br H H


4 But13diene react with hydrogen iodide to form 23 diiodobutane The reaction uses two moles of hydrogen iodide moleculestwo iodine atoms and two hydrogen atoms to break the two double bonds


But13diene  iodine 23diiodobutane


H2C CH CHCH2  2HI2 H3CCHICHI  CH3


H C C  C  C H  2H  I H  C C  C  C H


H I I H


iv Reaction with brominechlorine water


Chlorine and bromine water is formed when the halogen is dissolved in distilled waterChlorine water has the formular HOClhypochlorouschloricIacid Bromine water has the formular HOBrhydrobromicIacid


During the addition reaction the halogen move to one carbon and the OH to the other carbon in the alkene at the CC double bond to form a halogenoalkanol


Bromine water  Alkene  bromoalkanol


Chlorine water  Alkene  bromoalkanol


Examples


1Ethene reacts with bromine water to form bromoethanol


Chemical equation


H2CCH2  HOBr H2 Br C  CH2 OH


H H H H


C  C  Br  OH Br  C  C  OH


Ethene  Bromine water bromoethanol


2Propene reacts with chlorine water to form chloropropan2ol  2chloropropan1ol


IH3C CHCH2  HOCl H3C CHCl  CH2OH


Propene  Chlorine water 2chloropropane


H H H H H H


H C C  C  HO  Cl H  C  C  C OH


H H H Cl H


IIH3C CHCH2  HOCl H3C CHOH  CH2Cl


Propene  Chlorine chloropropan2ol


H C C  C  HO  Cl H  C  C  C Cl


H H H OH H


3Both But1ene and But2ene react with bromine water to form 2bromobutan1ol 3bromobutan2ol respectively


IBut1ene  bromine water 2bromobutan1ol


H3C CH2 CHCH2  HOBr H3C CH2CH Br  CH2OH


H H H H H H H H


H C C  C  C  HO Br H  C C  C  C OH


H H H H H Br H


IIBut2ene  bromine water 3bromobutan2ol


H3C CH CHCH3  HOBr H3C CH2OHCH Br CH3


4 But13diene reacts with bromine water to form Butan13diol


The reaction uses two moles of bromine water molecules to break the two double bonds


But13diene  bromine water 24dibromobutan13diol


H2C CH CHCH2  2HOBr H2COH CHBrCHOH CHBr


H C C  C  C H  2HO  Br H  C C  C  C H


HO Br HO Br


v Oxidation


Alkenes are oxidized to alkanols with duodouble functional groups by oxidizing agents


When an alkene is bubbled into orange acidified potassiumsodium dichromate VI solutionthe colour of the oxidizing agent changes to green


When an alkene is bubbled into purple acidified potassiumsodium manganateVII solution the oxidizing agent is decolorized


Examples


1Ethene is oxidized to ethan12diol by acidified potassiumsodium manganateVII solution acidified potassiumsodium dichromateVI solution


The purple acidified potassiumsodium manganateVII solution is decolorized


The orange acidified potassiumsodium dichromateVI solution turns to green


Chemical equation


H2CCH2 O in HK2Cr2O7 HO CH2  CH2 OH


H H H H


C  C O in HKMnO4 H  C  C  H


H H OH OH


Ethene  O in HKMnO4 ethan12diol


2 Propene is oxidized to propan12diol by acidified potassiumsodium manganateVII solution acidified potassiumsodium dichromateVI solution


H3C CHCH2 O in HKMnO4 H3C CHOH  CH2OH


Propene O in HKMnO4 propan12diol


H H H H H H


H C C  C O in HKMnO4 H  C  C  C OH


H H H OH H


3Both But1ene and But2ene react with bromine water to form butan12diol and butan23diol


IBut1ene  O in HKMnO4 butan12diol


H3C CH2 CHCH2  O H3C CH2CHOH  CH2OH


H H H H H H H H


H C C  C  C  O H  C C  C  C OH


H H H H H OH H


v Hydrolysis


Hydrolysis is the reaction of a compound with wateraddition of HOH to a compound


Alkenes undergo hydrolysis to form alkanols


This takes place in two steps


iAlkenes react with concentrated sulphuricVIacid at room temperature and pressure to form alkylhydrogen sulphateVI


Alkenes  concentrated sulphuricVIacid  alkylhydrogen sulphateVI


iiOn adding water to alkylhydrogen sulphateVI then warming an alkanol is formed


alkylhydrogen sulphateVI  water warm Alkanol


Examples


iEthene reacts with cold concentrated sulphuricVIacid to form ethyl hydrogen sulphateVII


Chemical equation


H2CCH2  H2SO4 CH3  CH2OSO3H


H H H OSO3H


C  C  H2SO4 H  C  C  H


H H H H


Ethene  H2SO4 ethylhydrogen sulphateVI


ii Ethylhydrogen sulphateVI is hydrolysed by water to ethanol


CH3  CH2OSO3H  H2O CH3  CH2OH  H2SO4


H OSO3H H OH


H  C  C  H  H2O H  C  C  H  H2SO4


ethylhydrogen sulphateVI  H2O Ethanol


2 Propene reacts with cold concentrated sulphuricVIacid to form propyl hydrogen sulphateVII


CH3H2CCH2  H2SO4 CH3CH2  CH2OSO3H


H H H H H OSO3H


C  C  C  H  H2SO4 H  C  C  C  H


H H H H H H


Propene  H2SO4 propylhydrogen sulphateVI


ii Propylhydrogen sulphateVI is hydrolysed by water to propanol


Chemical equation


H H OSO3H H H OH


H  C  C  C  H  H2O H  C  C  C  H  H2SO4


propylhydrogen sulphateVI  H2O propanol


vi Polymerizationself addition


Addition polymerization is the process where a small unsaturated monomer alkene  molecule join together to form a large saturated molecule


Only alkenes undergo addition polymerization


Addition polymers are named from the alkenemonomer making the polymer and adding the prefix poly before the name of monomer to form a polyalkene


During addition polymerization


ithe double bond in alkenes break


iifree radicals are formed


iiithe free radicals collide with each other and join to form a larger molecule The more collisions the larger the molecule


Examples of addition polymerization


1Formation of Polyethene


Polyethene is an addition polymer formed when ethene moleculemonomer join together to form a large moleculepolymer at high temperatures and pressure


During polymerization


imany molecules are brought nearer to each other by the high pressurewhich reduces the volume occupied by reacting particles


H H H H H H H H


C  C  C  C  C  C  C  C


Ethene  Ethene  Ethene  Ethene


iithe double bond joining the ethane molecule break to free readicals


Ethene radical  Ethene radical  Ethene radical  Ethene radical


iiithe free radicals collide with each other and join to form a larger molecule


H H H H H H H H lone pair of electrons


Lone pair of electrons can be used to join more monomers to form longer polyethene


Polyethene molecule can be represented as


H H H H H H H H extension of


moleculepolymer


Since the molecule is a repetition of one monomer then the polymer is


H H


C  C n


Where n is the number of monomers in the polymer The number of monomers in the polymer can be determined from the molar mass of the polymer and monomer from the relationship


Number of monomersrepeating units in monomer  Molar mass polymer


Molar mass monomer


Examples


Polythene has a molar mass of 4760Calculate the number of ethene molecules in the polymerC120 H10


Number of monomersrepeating units in polyomer  Molar mass polymer


Molar mass ethene C2H4  28 Molar mass polyethene  4760


Substituting 4760  170 ethene molecules


The commercial name of polyethene is polythene


It is an elastic tough transparent and durable plastic


Polythene is used


iin making plastic bag


iibowls and plastic bags


iiipackaging materials


2Formation of Polychlorethene


Polychloroethene is an addition polymer formed when chloroethene moleculemonomer join together to form a large moleculepolymer at high temperatures and pressure


During polymerization


H H H H H H H H


C  C  C  C  C  C  C  C


H Cl H Cl H Cl H Cl


chloroethene  chloroethene  chloroethene  chloroethene


iithe double bond joining the chloroethene molecule break to free radicals


H H H H H H H H lone pair of electrons


Lone pair of electrons can be used to join more monomers to form longer polychloroethene


Polychloroethene molecule can be represented as


H H H H H H H H extension of


moleculepolymer


H H


C  C n


H Cl


Examples


Polychlorothene has a molar mass of 4760Calculate the number of chlorethene molecules in the polymerC120 H10Cl355


Molar mass monomer


Molar mass ethene C2H3Cl  625 Molar mass polyethene  4760


Substituting 4760  7716  77 polychloroethene moleculeswhole number


The commercial name of polychloroethene is polyvinylchloridePVC It is a tough nontransparent and durable plastic PVC is used


iin making plastic rope


iiwater pipes


iiicrates and boxes


3Formation of Polyphenylethene


Polyphenylethene is an addition polymer formed when phenylethene moleculemonomer join together to form a large moleculepolymer at high temperatures and pressure


During polymerization


imany molecules are brought nearer to each other by the high pressurewhich reduces the volume occupied by reacting particles


H H H H H H H H


C  C  C  C  C  C  C  C


H C6H5 H C6H5 H C6H5 H C6H5


phenylethene  phenylethene  phenylethene  phenylethene


iithe double bond joining the phenylethene molecule break to free radicals


iiithe free radicals collide with each other and join to form a larger molecule


H H H H H H H H lone pair of electrons


Lone pair of electrons can be used to join more monomers to form longer polyphenylethene


Polyphenylethene molecule can be represented as


Since the molecule is a repetition of one monomer then the polymer is


H H


C  C n


H C6H5


Examples


Polyphenylthene has a molar mass of 4760Calculate the number of phenylethene molecules in the polymerC120 H10


Number of monomersrepeating units in monomer  Molar mass polymer


Molar mass monomer


Molar mass ethene C8H8  104 Molar mass polyethene  4760


Substituting 4760  457692 45 polyphenylethene moleculeswhole number


The commercial name of polyphenylethene is polystyrene It is a very light durable plastic Polystyrene is used


iin making packaging material for carrying delicate items like computers radioncalculators


iiceiling tiles


iiiclothe linings


4Formation of Polypropene


Polypropene is an addition polymer formed when propene moleculemonomer join together to form a large moleculepolymer at high temperatures and pressure


During polymerization


H H H H H H H H


C  C  C  C  C  C  C  C


H CH3 H CH3 H CH3 H CH3


propene  propene  propene  propene


H H H H H H H H lone pair of electrons


Lone pair of electrons can be used to join more monomers to form longer propene


propene molecule can be represented as


H H


C  C n


H CH3


Examples


Polypropene has a molar mass of 4760Calculate the number of propene molecules in the polymerC120 H10


Molar mass monomer


Molar mass propene C3H8  44 Molar mass polyethene  4760


Substituting 4760  1081818 108 propene moleculeswhole number


iiceiling tiles


iiiclothe linings


5Formation of Polytetrafluorothene


Polytetrafluorothene is an addition polymer formed when tetrafluoroethene moleculemonomer join together to form a large moleculepolymer at high temperatures and pressure


During polymerization


imany molecules are brought nearer to each other by the high pressurewhich reduces the volume occupied by reacting particles


F F F F F F F F


C  C  C  C  C  C  C  C


tetrafluoroethene  tetrafluoroethene tetrafluoroethene tetrafluoroethene


iithe double bond joining the tetrafluoroethene molecule break to free radicals


iiithe free radicals collide with each other and join to form a larger molecule


F F F F F F F F lone pair of electrons


Lone pair of electrons can be used to join more monomers to form longer polytetrafluoroethene


polytetrafluoroethene molecule can be represented as


F F F F F F F F extension of


moleculepolymer


Since the molecule is a repetition of one monomer then the polymer is


F F


C  C n


Examples


Polytetrafluorothene has a molar mass of 4760Calculate the number of tetrafluoroethene molecules in the polymerC120 F19


Number of monomersrepeating units in monomer  Molar mass polymer


Molar mass monomer


Molar mass ethene C2F4  625 Molar mass polyethene  4760


Substituting 4760  7716  77 polychloroethene moleculeswhole number


The commercial name of polytetrafluorethenePTFE is TeflonPTFE It is a tough nontransparent and durable plastic PVC is used


iin making plastic rope


iiwater pipes


iiicrates and boxes


6Formation of rubber from Latex


Natural rubber is obtained from rubber trees


During harvesting an incision is made on the rubber tree to produce a milky white substance called latex


Latex is a mixture of rubber and lots of water


The latex is then added an acid to coagulate the rubber


Natural rubber is a polymer of 2methylbut13diene


During natural polymerization to rubber one double CC bond break to self add to another molecule The double bond remaining move to carbon 2 thus


H CH3 H H H CH3 H H


C  C  C  C  C  C  C  C


H H H H


Generally the structure of rubber is thus


H CH3 H H


C  C  C  C n


H H


Pure rubber is soft and stickyIt is used to make erasers car tyres Most of it is vulcanizedVulcanization is the process of heating rubber with sulphur to make it hardertougher


During vulcanization the sulphur atoms form a cross link between chains of rubber moleculespolymers This decreases the number of CC double bonds in the polymer


H S H H S H


H CH3 S H H CH3 S H


H H H H H H


Vulcanized rubber is used to make tyres shoes and valves


7Formation of synthetic rubber


Synthetic rubber is able to resist action of oilabrasion and organic solvents which rubber cannot


Common synthetic rubber is a polymer of 2chlorobut13diene


H Cl H H


CH2C Cl CH  CH2 H  C  C  C  C  H


During polymerization to synthetic rubber one double CC bond is broken to self add to another molecule The double bond remaining move to carbon 2 thus


H Cl H H H Cl H H


C  C  C  C  C  C  C  C


H H H H


C  C  C  C n


H H


Rubber is thus strengthened through vulcanization and manufacture of synthetic rubber


cTest for the presence of  C  C  double bond


iBurningcombustion


All unsaturated hydrocarbons with a  C  C  or  C  C  bond burn with a yellow sooty flame


Experiment


Scoop a sample of the substance provided in a clean metallic spatula Introduce it on a Bunsen burner


iiOxidation by acidified KMnO4K2Cr2O7


Bromine water Chlorine water and Oxidizing agents acidified KMnO4K2Cr2O7 change to unique colour in presence of  C  C


or  C  C  bond


Scoop a sample of the substance provided into a clean test tube Add 10cm3 of distilled water Shake Take a portion of the solution mixture Add three drops of acidified KMnO4K2Cr2O7


dSome uses of Alkenes


1 In the manufacture of plastic


2 Hydrolysis of ethene is used in industrial manufacture of ethanol


3 In ripening of fruits


4 In the manufacture of detergents


iii Alkynes


aNomenclatureNaming


These are hydrocarbons with a general formula CnH2n2 and C C double bond as the functional group  n is the number of Carbon atoms in the molecule


The carbon atoms are linked by at least one triple bond to each other and single bonds to hydrogen atoms


They include


Note


1 Since carbon is tetravalent each atom of carbon in the alkyne MUST always be bonded using four covalent bond four shared pairs of electrons including at the triple bond


2 Since Hydrogen is monovalent each atom of hydrogen in the alkyne MUST always be bonded using one covalent bondone shared pair of electrons


3 One member of the alkyne like alkenes and alkanes differ from the nextprevious by a CH2 groupmolar mass of 14 atomic mass unitsThey thus form a homologous series


eg


Propyne differ from ethyne by 14 amu one carbon and two Hydrogen atoms from ethyne


4A homologous series of alkenes like that of alkanes


i differ by a CH2 group from the next previous consecutively


ii have similar chemical properties


iiihave similar chemical formula with general formula CnH2n2


ivthe physical properties also show steady gradual change


5The  C  C  triple bond in alkyne is the functional group The functional group is the reacting site of the alkynes


6 The  C  C  triple bond in alkyne can easily be broken to accommodate more four more monovalent atoms The  C  C  triple bond in alkynes make it thus unsaturated like alkenes


7 Most of the reactions of alkynes like alkenes take place at the  C  C triple bond


bIsomers of alkynes


Isomers of alkynes have the same molecular general formula but different molecular structural formula


Isomers of alkynes are also named by using the IUPACInternational Union of Pure and Applied Chemistry system of nomenclaturenaming


The IUPAC system of nomenclature of naming alkynes uses the following basic rulesguidelines


1Identify the longest continuousstraight carbon chain which contains the  C  C triple bond to getdetermine the parent alkene


2 Number the longest chain form the end of the chain which contains the C  C triple bond so as  C  C triple bond get lowest number possible


3 Indicate the positions by splitting alkpositionsyne eg but2yne pent13diyne


4The position indicated must be for the carbon atom at the lower position in the


C  C triple bond ie


But2yne means the triple C  C is between Carbon 2and 3


Pent13diyne means there are two triple bonds one between carbon 1 and 2and another between carbon 3 and 4


5 Determine the position number and type of branches Name them as methyl ethyl propyl etc according to the number of alkyl carbon chains attached to the alkyne Name them fluorochlorobromoiodo if they are halogens


6Use prefix ditritetrapentahexa to show the number of triple  C  C bonds and branches attached to the alkyne


7Position isomers can be formed when the  C  C triple bond is shifted between carbon atoms eg


But2yne means the double  C  C is between Carbon 2and 3


But1yne means the double  C  C is between Carbon 1and 2


Both But1yne and But2yne are position isomers of Butyne


9 Like alkanes and alkynes  an alkyl group can be attached to the alkyne Chainbranch isomers are thus formed


Butyne and 2methyl propyne both have the same general formular but different branching chain


cPreparation of Alkynes


Ethyne is prepared from the reaction of water on calcium carbide The reaction is highly exothermic and thus a layer of sand should be put above the calcium carbide to absorb excess heat to prevent the reaction flask from breaking CopperIIsulphateVI is used to catalyze the reaction


Chemical equation


CaC2s  2 H2Ol  CaOH 2 aq  C2H2 g


dProperties of alkynes


I Physical properties


Like alkanes and alkenes alkynes are colourles gases solids and liquids that are not poisonous


They are slightly soluble in water The solubility in water decrease as the carbon chain and as the molar mass increase but very soluble in organic solvents like tetrachloromethane and methylbenzene Ethyne has a pleasant taste when pure


The melting and boiling point increase as the carbon chain increase


This is because of the increase in vanderwaals intermolecular forces as the carbon chain increase The 1st three straight chain alkynes ethynepropyne and but1yneare gases at room temperature and pressure


The density of straight chain alkynes increase with increasing carbon chain as the intermolecular forces increases reducing the volume occupied by a given mass of the alkyne


Summary of physical properties of the 1st five alkenes


II Chemical properties


aBurningcombustion


Alkynes burn with a yellow luminous very sooty smoky flame in excess air to form carbonIV oxide and water


Alkyne  Air  carbonIV oxide  water excess airoxygen


Alkenes burn with a yellow luminous verysooty smoky flame in limited air to form carbonII oxidecarbon and water


Alkyne  Air  carbonII oxide carbon  water limited air


Burning of alkynes with a yellow luminous sooty smoky flame is a confirmatory test for the presence of the  C  C  triple bond because they have very high CH ratio


Examples of burning alkynes


1a Ethyne when ignited burns with a yellow very sooty flame in excess air to form carbonIV oxide and water


Ethyne  Air  carbonIV oxide  water excess airoxygen


2C2H2g  5O2g  4CO2g  2H2Olg


b Ethyne when ignited burns with a yellow sooty flame in limited air to form a mixture of unburnt carbon and carbonII oxide and water


Ethyne  Air  carbonII oxide  water limited air


C2H2g  O2g  2CO2g  C  2H2Olg


2a Propyne when ignited burns with a yellow sooty flame in excess air to form carbonIV oxide and water


Propyne  Air  carbonIV oxide  water excess airoxygen


C3H4g  4O2g  3CO2g  2H2Olg


a Propyne when ignited burns with a yellow sooty flame in limited air to form carbonII oxide and water


Propene  Air  carbonIV oxide  water excess airoxygen


2C3H4g  5O2g  6COg  4H2Olg


bAddition reactions


An addition reaction is one which an unsaturated compound reacts to form a saturated compound Addition reactions of alkynes are also named from the reagent used to cause the additionconvert the triple  C  C to single C C bond


iHydrogenation


Hydrogenation is an addition reaction in which hydrogen in presence of PalladiumNickel catalyst at 150oC temperatures react with alkynes to form alkenes then alkanes


Examples


1During hydrogenation two hydrogen atom in the hydrogen molecule attach itself to one carbon and the other two hydrogen to the second carbon breaking the triple bond to double the single


Chemical equation


HC  CH  H2 NiPa  H2C  CH2  H2 NiPa  H2C  CH2


H H H H H H


C  C  H  H  NiPa  H  C  C  H  H  H  NiPa  H  C  C  H


2Propyne undergo hydrogenation to form Propane


H3C CH  CH2  2H2 NiPa H3C CH  CH3


H C C  C  2H  H  NiPa H  C  C  C H


H H H H H


3a But1yne undergo hydrogenation to form Butane


But1yne  Hydrogen NiPa Butane


H3C CH2 C  CH  2H2 NiPa H3C CH2CH  CH3


H H H H H H H


H C C  C  C  2H  H  NiPa H  C C  C  C H


b But2yne undergo hydrogenation to form Butane


But2yne  Hydrogen NiPa Butane


H3C C  C CH2  2H2 NiPa H3C CH2CH  CH3


H C C  C  C H  2H  H NiPa H  C C  C  C H


ii Halogenation


Halogenation is an addition reaction in which a halogen Fluorine chlorine bromine iodine reacts with an alkyne to form an alkene then alkane


The reaction of alkynes with halogens with alkynes is faster than with alkenes The triple bond in the alkyne break and form a double then single bond


The colour of the halogen fades as the number of moles of the halogens remaining unreacted decreases


Two bromine atoms bond at the 1st carbon in the triple bond while the other two goes to the 2nd carbon


Examples


1Ethyne reacts with brown bromine vapour to form 1122tetrabromoethane


Chemical equation


HC  CH  2Br2 H Br2 C  CH Br2


H H H H


C  C  2Br  Br Br  C  C  Br


Br Br


Ethyne  Bromine 1121tetrabromoethane


2Propyne reacts with chlorine to form 1122tetrachloropropane


H3C C  CH  2Cl2 H3C CHCl2  CHCl2


Propyne  Chlorine 1122tetrachloropropane


H H Cl H


H C C  C  2Cl  Cl H  C  C  C Cl


H H H Cl Cl


Propyne  Iodine 1122tetraiodopropane


H3C C  CH  2I2 H3C CHI2  CHI2


H H H H H I H


H C C  C  C  2I  I H  C C  C  C I


H H H H I I


3aBut1yne undergo halogenation to form 1122tetraiodobutane with iodine


Chemical equation


But1yne  iodine 1122tetrabromobutane


H3C CH2 C  CH  2I2 H3C CH2C I2  CHI2


H C C  C  C H  2I  I H  C C  C  C H


H H H H H I I


b But2yne undergo halogenation to form 2233tetrafluorobutane with fluorine But2yne  Fluorine 2233tetrafluorobutane


H3C C  C CH2  2F2 H3C CF2CF2  CH3


H H H H H H H H


H C C  C  C H  F  F H  C C  C  C H


H H H H H H


4 But13diyne should undergo halogenation to form 1123344 octaiodobutane The reaction uses four moles of iodine moleculeseight iodine atoms to break the two2 triple double bonds at carbon 1 and 2


But13diene  iodine 1234tetraiodobutane


H C  C C  C H  4I2 H C I2 C I2 C I2 C H I2


I I I I


H C C  C  C H  4I  I H  C C  C  C H


iii Reaction with hydrogen halides


Hydrogen halides reacts with alkyne to form a halogenoalkene then halogenoalkane The triple bond in the alkyne break and form a double then single bond


The main compound is one which the hydrogen atom bond at the carbon with more hydrogen


Examples


1 Ethyne reacts with hydrogen bromide to form bromoethane


Chemical equation


H C  C H  2HBr H3 C  CH Br2


H H H H


C  C  2H  Br H  C  C  Br


H Br


Ethyne  Bromine 11dibromoethane


2 Propyne reacts with hydrogen iodide to form 22diiodopropane as the main product


H3C C  CH  2HI H3C CHI2  CH3


Propene  Chlorine 22dichloropropane


H H I H


H C C  C  2H  I H  C  C  C H


H H H I H


3 Both But1yne and But2yne reacts with hydrogen bromide to form 22 dibromobutane


But1ene  hydrogen bromide 22dibromobutane


H3C CH2 C  CH  2HBr H3C CH2CHBr CH3


H H H H Br H


H C C  C  C  2H  Br H  C C  C  C H


H H H H H Br H


But2yne  Hydrogen bromide 22dibromobutane


H3C C  C CH3  2HBr H3C CBr2CH2  CH3


H H H Br H H


H C C  C  C H  2Br  H H  C C  C  C H


4 But13diene react with hydrogen iodide to form 23 diiodobutane The reaction uses four moles of hydrogen iodide moleculesfour iodine atoms and two hydrogen atoms to break the two double bonds


But13diyne  iodine 2233tetraiodobutane


H C  C C  C H  4HI H3C C I2 C I2 CH3


H H H I I H


H C C  C  C H  4H  I H  C C  C  C H


H I I H


BALKANOLSAlcohols


A INTRODUCTION


Alkanols belong to a homologous series of organic compounds with a general formula CnH2n 1 OH and thus OH as the functional group The 1st ten alkanols include


Alkanols like Hydrocarbons alkanesalkenesalkynes form a homologous series where


igeneral name is derived from the alkane name then ending with ol


iithe members have OH as the fuctional group


iiithey have the same general formula represented by ROH where R is an alkyl group


iv each member differ by CH2 group from the nextprevious


vthey show a similar and gradual change in their physical properties eg boiling and melting points


vithey show similar and gradual change in their chemical properties


B ISOMERS OF ALKANOLS


Alkanols exhibit both structural and position isomerism The isomers are named by using the following basic guidelines


iLike alkanes  identify the longest carbon chain to be the parent name


iiIdentify the position of the OH functional group to give it the smallest lowest position


iii Identify the type and position of the side branches


Practice examples of isomers of alkanols


iIsomers of propanol C3H7OH


CH3CH2CH2OH  Propan1ol


OH


CH3CHCH3  Propan2ol


Propan2ol and Propan1ol are position isomers because only the position of the OH functional group changes


iiIsomers of Butanol C4H9OH


CH3 CH2 CH3 CH2 OH Butan1ol


CH3 CH2 CH CH3


OH Butan2ol


CH3 CH3 CH3


OH 2methylpropan2ol


Butan2ol and Butan1ol are position isomers because only the position of the OH functional group changes


2methylpropan2ol is both a structural and position isomers because both the position of the functional group and the arrangement of the atoms in the molecule changes


iiiIsomers of Pentanol C5H11OH


CH3 CH2 CH2CH2CH2 OH Pentan1ol Position isomer


OH Pentan2ol Position isomer


CH3 CH2 CH CH2 CH3


OH Pentan3ol Position isomer


CH3 CH2 CH2 C CH3


OH 2methylbutan2ol Position structural isomer


CH3 CH2 CH2 C CHOH


CH3 22dimethylbutan1ol Position structural isomer


CH3 CH2 CH C CH3


CH3 OH 23dimethylbutan1ol Position structural isomer


CClH2 CCl CH3


OH


CClH2 CHCl CH2


vi Ethan12diol


H H


HOCH2CH2OH HO  C  C  OH


vii Propan123triol H OH H


HOCH2CHOHCH2OH HO  C C  C  OH


H H H


C LABORATORY PREPARATION OF ALKANOLS


For decades the world over people have been fermenting grapes juice sugar carbohydrates and starch to produce ethanol as a social drug for relaxation


In large amount drinking of ethanol by mammals human beings causes mental and physical lack of coordination


Prolonged intake of ethanol causes permanent mental and physical lack of coordination because it damages vital organs like the liver


Fermentation is the reaction where sugar is converted to alcoholalkanol using biological catalystenzymes in yeast


It involves three processes


iConversion of starch to maltose using the enzyme diastase


C6H10O5n s  H2Ol diastase enzyme  C12H22O11aq


Starch Maltose


iiHydrolysis of Maltose to glucose using the enzyme maltase


C12H22O11aq H2Ol  maltase enzyme 2 C6H12O6aq


Maltose glucose


iiiConversion of glucose to ethanol and carbonIVoxide gas using the enzyme zymase


C6H12O6aq  zymase enzyme  2 C2H5OHaq  2CO2g


glucose Ethanol


At concentration greater than 15 by volume the ethanol produced kills the yeast enzyme stopping the reaction


To increases the concentration fractional distillation is done to produce spirits eg Brandy40 ethanol


Methanol is much more poisonous toxic than ethanol


Taken large quantity in small quantity it causes instant blindness and liver killing the consumer victim within hours


School laboratory preparation of ethanol from fermentation of glucose


Measure 100cm3 of pure water into a conical flask


Add about five spatula end full of glucose


Stir the mixture to dissolve


Add about one spatula end full of yeast


Set up the apparatus as below


Preserve the mixture for about three days


DPHYSICAL AND CHEMICAL PROPERTIES OF ALKANOLS


Use the prepared sample above for the following experiments that shows the characteristic properties of alkanols


Role of yeast


Yeast is a single cell fungus which contains the enzyme maltase and zymase that catalyse the fermentation process


Observations in lime water


A white precipitate is formed that dissolve to a colourless solution later Lime waterCalcium hydroxide reacts with carbonIV0xide produced during the fermentation to form insoluble calcium carbonate and water


More carbon IV0xide produced during fermentation react with the insoluble calcium carbonate and water to form soluble calcium hydrogen carbonate


CaOH2aq  CO2 g  CaCO3s


H2Ol  CO2 g  CaCO3s  CaHCO3 2 aq


cEffects on litmus paper


Experiment


Take the prepared sample and test with both blue and red litmus papers


Repeat the same with pure ethanol and methylated spirit


Sample Observation table


Explanation


Alkanols are neutral compoundssolution that have characteristic sweet smell and taste


They have no effect on both blue and red litmus papers


dSolubility in water


Place about 5cm3 of prepared sample into a clean test tube Add equal amount of distilled water


Observation


No layers formed between the two liquids


Ethanol is miscible in waterBoth ethanol and water are polar compounds


The solubility of alkanols decrease with increase in the alkyl chainmolecular mass


The alkyl group is insoluble in water while OH functional group is soluble in water


As the molecular chain becomes longer the effect of the alkyl group increases as the effect of the functional group decreases


eMeltingboiling point


Place pure ethanol in a long boiling tube Determine its boiling point


Pure ethanol has a boiling point of 78oC at sea levelone atmosphere pressure


The melting and boiling point of alkanols increase with increase in molecular chainmass


This is because the intermolecularvanderwaals forces of attraction between the molecules increase


More heat energy is thus required to weaken the longer chain during melting and break during boiling


fDensity


Density of alkanols increase with increase in the intermolecularvanderwaals forces of attraction between the molecule making it very close to each other


This reduces the volume occupied by the molecule and thus increase the their mass per unit volume density


Summary table showing the trend in physical properties of alkanols


gBurning


Experiment


Place the prepared sample in a watch glass Ignite Repeat with pure ethanol and methylated spirit


ObservationExplanation


Fermentation produce ethanol with a lot of waterabout a ratio of 13which prevent the alcohol from igniting


Pure ethanol and methylated spirit easily catch fire  highly flammable


They burn with an almost colourless nonsootynonsmoky blue flame to form carbonIV oxide in excess airoxygenor carbonII oxide limited air and water


Ethanol is thus a saturated compound like alkanes


Chemica equation


C2 H5OHl  3O2 g  3H2Ol  2CO2 g  excess air


C2 H5OHl  2O2 g  3H2Ol  2CO g  limited air


2CH3OHl  3O2 g  4H2Ol  2CO2 g  excess air


2 CH3OHl  2O2 g  4H2Ol  2CO g  limited air


2C3 H7OHl  9O2 g  8H2Ol  6CO2 g  excess air


C3 H7OHl  3O2 g  4H2Ol  3CO g  limited air


2C4 H9OHl  13O2 g  20H2Ol  8CO2 g  excess air


C4 H9OHl  3O2 g  4H2Ol  3CO g  limited air


Due to its flammability ethanol is used


as a fuel in spirit lamps


as gasohol when blended with gasoline


hFormation of alkoxides


Experiment


Cut a very small piece of sodium Put it in a beaker containing about 20cm3 of the prepared sample in a beaker


Test the products with litmus papers Repeat with absolute ethanol and methylated spirit


Sample observations


Explanations


Sodiumpotassium reacts slowly with alkanols to form basic solution called alkoxides and producing hydrogen gas


If the alkanol has some water the metals react faster with the water to form soluble hydroxidesalkalis ie


Sodium  Alkanol  Sodium alkoxides  Hydrogen gas


Potassium  Alkanol  Potassium alkoxides  Hydrogen gas


Sodium  Water  Sodium hydroxides  Hydrogen gas


Potassium  Water  Potassium hydroxides  Hydrogen gas


Examples


1Sodium metal reacts with ethanol to form sodium ethoxide


Sodium metal reacts with water to form sodium Hydroxide


2CH3CH2OHl  2Nas  2CH3CH2ONa aq  H2 s


2H2Ol  2Nas  2NaOH aq  H2 s


2Potassium metal reacts with ethanol to form Potassium ethoxide


Potassium metal reacts with water to form Potassium Hydroxide


2CH3CH2OHl  2Ks  2CH3CH2OK aq  H2 s


2H2Ol  2Ks  2KOH aq  H2 s


3Sodium metal reacts with propanol to form sodium propoxide


2CH3CH2 CH2OHl  2Nas  2CH3CH2 CH2ONa aq  H2 s


4Potassium metal reacts with propanol to form Potassium propoxide


2CH3CH2 CH2OHl  2Ks  2CH3CH2 CH2OK aq  H2 s


5Sodium metal reacts with butanol to form sodium butoxide


2CH3CH2 CH2 CH2OHl  2Nas  2CH3CH2 CH2 CH2ONa aq  H2 s


6Sodium metal reacts with pentanol to form sodium pentoxide


2CH3CH2 CH2 CH2 CH2OHl2Nas  2CH3CH2 CH2 CH2 CH2ONa aq  H2 s


iFormation of EstersEsterification


Experiment


Place 2cm3 of ethanol in a boiling tube


Add equal amount of ethanoic acidTo the mixture add carefully 2drops of concentrated sulphuricVIacid


WarmHeat gently


Pour the mixture into a beaker containing about 50cm3 of cold water


Smell the products


Repeat with methanol


Sample observations


Explanation


Alkanols react with alkanoic acids to form a group of homologous series of sweet smelling compounds called esters and water This reaction is catalyzed by concentrated sulphuricVIacid in the laboratory


Alkanol  Alkanoic acid Conc H2SO4 Ester  water


Naturally esterification is catalyzed by sunlight Each ester has a characteristic smell derived from the many possible combinations of alkanols and alkanoic acids that create a variety of known naturalmostly in fruits and syntheticmostly in juices esters


Esters derive their names from the alkanol first then alkanoic acids The alkanol becomes an alkyl group and the alkanoic acid becomes alkanoate hence alkylalkanoate eg


Ethanol  Ethanoic acid  Ethylethanoate  Water


Ethanol  Propanoic acid  Ethylpropanoate  Water


Ethanol  Methanoic acid  Ethylmethanoate  Water


Ethanol  butanoic acid  Ethylbutanoate  Water


Propanol  Ethanoic acid  Propylethanoate  Water


Methanol  Ethanoic acid  Methyethanoate  Water


Methanol  Decanoic acid  Methyldecanoate  Water


Decanol  Methanoic acid  Decylmethanoate  Water


During the formation of the ester the O joining the alkanol and alkanoic acid comes from the alkanol


R1 COOH  R2 OH  R1 COO R2  H2O


eg


1 Ethanol reacts with ethanoic acid to form the ester ethyl ethanoate and water


Ethanol  Ethanoic acid Conc H2SO4 Ethylethanoate  Water


C2H5OH l  CH3COOHl Conc H2SO4  CH3COO C2H5aq H2Ol


CH3CH2OH l CH3COOHl Conc H2SO4  CH3COOCH2CH3aq H2Ol


2 Ethanol reacts with propanoic acid to form the ester ethylpropanoate and water


Ethanol  Propanoic acid Conc H2SO4 Ethylethanoate  Water


C2H5OH l CH3 CH2COOHl Conc H2SO4 CH3CH2COO C2H5aq H2Ol


CH3CH2OH l CH3 CH2COOHl Conc H2SO4  CH3 CH2COOCH2CH3aq H2Ol


3 Methanol reacts with ethanoic acid to form the ester methyl ethanoate and water


Methanol  Ethanoic acid Conc H2SO4 Methylethanoate  Water


CH3OH l  CH3COOHl Conc H2SO4  CH3COO CH3aq H2Ol


4 Methanol reacts with propanoic acid to form the ester methyl propanoate and water


Methanol  propanoic acid Conc H2SO4 Methylpropanoate  Water


CH3OH l CH3 CH2COOHl Conc H2SO4  CH3 CH2COO CH3aq H2Ol


5 Propanol reacts with propanoic acid to form the ester propylpropanoate and water


Propanol  Propanoic acid Conc H2SO4 Ethylethanoate  Water


C3H7OH l CH3 CH2COOHl Conc H2SO4 CH3CH2COO C3H7aq H2Ol


CH3CH2 CH2OH l CH3 CH2COOHl Conc H2SO4  CH3 CH2COOCH2 CH2CH3aq H2Ol


jOxidation


Experiment


Place 5cm3 of absolute ethanol in a test tubeAdd three drops of acidified potassium manganateVIIShake thoroughly for one minutewarmTest the solution mixture using pH paper Repeat by adding acidified potassium dichromateVII


Sample observation table


Explanation


Both acidified KMnO4 and K2Cr2O7 are oxidizing agentsadd oxygen to other compounds They oxidize alkanols to a group of homologous series called alkanals then further oxidize them to alkanoic acidsThe oxidizing agents are themselves reduced hence changing their colour


i Purple KMnO4 is reduced to colourless Mn2


iiOrange K2Cr2O7is reduced to green Cr3


The pH of alkanoic acids show they have few H because they are weak acids ie


Alkanol  O  Alkanal  O  alkanoic acid


NB The O comes from the oxidizing agents acidified KMnO4 or K2Cr2O7


Examples


1When ethanol is warmed with three drops of acidified KMnO4 there is decolorization of KMnO4


Ethanol  O  Ethanal  O  Ethanoic acid


CH3CH2OH  O  CH3CH2O  O  CH3COOH


2When methanol is warmed with three drops of acidified K2Cr2O7 the orange colour of acidified K2Cr2O7 changes to green


methanol  O  methanal  O  methanoic acid


CH3OH  O  CH3O  O  HCOOH


3When propanol is warmed with three drops of acidified K2Cr2O7 the orange colour of acidified K2Cr2O7 changes to green


Propanol  O  Propanal  O  Propanoic acid


CH3CH2 CH2OH  O  CH3CH2 CH2O  O  CH3 CH2COOH


4When butanol is warmed with three drops of acidified K2Cr2O7 the orange colour of acidified K2Cr2O7 changes to green


Butanol  O  Butanal  O  Butanoic acid


CH3CH2 CH2 CH2OH  O CH3CH2 CH2CH2O O  CH3 CH2COOH


Air slowly oxidizes ethanol to dilute ethanoic acid commonly called vinegar If beer is not tightly corked a lot of carbonIVoxide escapes and there is slow oxidation of the beer making it flat


kHydrolysis Hydration and Dehydration


I HydrolysisHydration is the reaction of a compoundsubstance with water


Alkenes react with water vapoursteam at high temperatures and high pressures in presence of phosphoric acid catalyst to form alkanolsie


Alkenes  Water  H3PO4 catalyst Alkanol


Examples


iEthene is mixed with steam over a phosphoric acid catalyst at 300oC temperature and 60 atmosphere pressure to form ethanol


Ethene  water 60 atm300oC H3PO4  Ethanol


H2C CH2 g  H2Ol 60 atm300oC H3PO4  CH3 CH2OHl


This is the main method of producing large quantities of ethanol instead of fermentation


ii Propene  water 60 atm300oC H3PO4  Propanol


CH3C CH2 g  H2Ol 60 atm300oC H3PO4  CH3 CH2 CH2OHl


iii Butene  water 60 atm300oC H3PO4  Butanol


CH3 CH2 CCH2 g  H2Ol 60 atm300oC H3PO4  CH3 CH2 CH2 CH2OHl


II Dehydration is the process which concentrated sulphuricVIacid dehydrating agent removes water from a compoundsubstances


Concentrated sulphuricVIacid dehydrates alkanols to the corresponding alkenes at about 180oC ie


Alkanol Conc H2 SO4180oC Alkene  Water


1 At 180oC and in presence of Concentrated sulphuricVIacid ethanol undergoes dehydration to form ethene


Ethanol 180oC H2SO4  Ethene  Water


CH3 CH2OHl 180oC H2SO4  H2C CH2 g  H2Ol


2 Propanol undergoes dehydration to form propene


Propanol 180oC H2SO4  Propene  Water


CH3 CH2 CH2OHl 180oC H2SO4  CH3CH CH2 g  H2Ol


3 Butanol undergoes dehydration to form Butene


Butanol 180oC H2SO4  Butene  Water


CH3 CH2 CH2CH2OHl 180oC H2SO4  CH3 CH2C CH2 g  H2Ol


3 Pentanol undergoes dehydration to form Pentene


Pentanol 180oC H2SO4  Pentene  Water


CH3 CH2 CH2 CH2 CH2OHl180oC H2SO4CH3 CH2 CH2C CH2 gH2Ol


lSimilarities of alkanols with Hydrocarbons


I Similarity with alkanes


Both alkanols and alkanes burn with a blue nonsooty flame to form carbonIVoxidein excess airoxygencarbonIIoxidein limited air and water This shows they are saturated with high CH ratio eg


Both ethanol and ethane ignite and burns in air with a blue nonsooty flame to form carbonIVoxidein excess airoxygencarbonIIoxidein limited air and water


CH2 CH2OHl  3O2g Excess air 2CO2 g  3H2 Ol


CH2 CH2OHl  2O2g Limited air 2CO g  3H2 Ol


CH3 CH3g  3O2g Excess air 2CO2 g  3H2 Ol


2CH3 CH3g  5O2g Limited air 4CO g  6H2 Ol


II Similarity with alkenesalkynes


Both alkanolsROH and alkenesalkyneswith  C  C  double and  C  C triple  bond


idecolorize acidified KMnO4


iiturns Orange acidified K2Cr2O7 to green


AlkanolsROH are oxidized to alkanalsRO ant then alkanoic acidsROOH


Alkenes are oxidized to alkanols with duodouble functional groups


Examples


1When ethanol is warmed with three drops of acidified K2Cr2O7 the orange of acidified K2Cr2O7 turns to green Ethanol is oxidized to ethanol and then to ethanoic acid


Ethanol  O  Ethanal  O  Ethanoic acid


CH3CH2OH  O  CH3CH2O  O  CH3COOH


2When ethene is bubbled in a test tube containing acidified K2Cr2O7 the orange of acidified K2Cr2O7 turns to green Ethene is oxidized to ethan12diol


Ethene  O  Ethan12diol


H2CCH2  O  HOCH2 CH2OH


III Differences with alkenesalkynes


Alkanols do not decolorize bromine and chlorine water


Alkenes decolorizes bromine and chlorine water to form halogenoalkanols


Example


When ethene is bubbled in a test tube containing bromine waterthe bromine water is decolorized Ethene is oxidized to bromoethanol


Ethene  Bromine water  Bromoethanol


H2CCH2  HOBr  BrCH2 CH2OH


IV Differences in melting and boiling point with Hydrocarbons


Alkanos have higher melting point than the corresponding hydrocarbon alkanealkenealkyne


This is because most alkanols exist as dimerA dimer is a molecule made up of two other molecules joined usually by vanderwaals forceshydrogen bond or dative bonding


Two alkanol molecules form a dimer joined by hydrogen bonding


In Ethanol the oxygen atom attractspulls the shared electrons in the covalent bond more to itself than Hydrogen


This creates a partial negative charge  on oxygen and partial positive charge on hydrogen


Two ethanol molecules attract each other at the partial charges through Hydrogen bonding forming a dimmer


H H H


H C C O H H


H H H O C C H


H H


Dimerization of alkanols means more energy is needed to breakweaken the Hydrogen bonds before breakingweakening the intermolecular forces joining the molecules of all organic compounds during boilingmelting


EUSES OF SOME ALKANOLS


aMethanol is used as industrial alcohol and making methylated spirit


bEthanol is used


1 as alcohol in alcoholic drinks eg Beer wines and spirits


2as antiseptic to wash woulds


3in manufacture of vanishes ink glue and paint because it is volatile and thus easily evaporate


4as a fuel when blended with petrol to make gasohol


BALKANOIC ACIDS Carboxylic acids


A INTRODUCTION


Alkanoic acids belong to a homologous series of organic compounds with a general formula CnH2n 1 COOH and thus COOH as the functional group The 1st ten alkanoic acids include


Alkanoic acids like alkanols alkanesalkenesalkynes form a homologous series where


ithe general name of an alkanoic acids is derived from the alkane name then ending with oic acid as the table above shows


ii the members have RCOOHR COH as the functional group


O


iiithey have the same general formula represented by RCOOH where R is an alkyl group


iveach member differ by CH2 group from the nextprevious


vthey show a similar and gradual change in their physical properties eg boiling and melting point


vithey show similar and gradual change in their chemical properties


vii since they are acids they show similar properties with mineral acids


B ISOMERS OF ALKANOIC ACIDS


lkanoic acids exhibit both structural and position isomerism The isomers are named by using the following basic guidelines


iLike alkanes identify the longest carbon chain to be the parent name


iiIdentify the position of the COH functional group to give it the smallest


lowest position


iiiIdentify the type and position of the side group branches


Practice examples on isomers of alkanoic acids


1Isomers of butanoic acid C3H7COOH


CH3 CH2 CH2 COOH


Butan1oic acid


H2C C COOH 2methylpropan1oic acid


2methylpropan1oic acid and Butan1oic acid are structural isomers because the position of the functional group does not change but the arrangement of the atoms in the molecule does


2Isomers of pentanoic acid C4H9COOH


CH3CH2CH2CH2 COOH pentan1oic acid


CH3CH2CH COOH 2methylbutan1oic acid


H3C C COOH 22dimethylpropan1oic acid


3Ethan12dioic acid


O O


HOOC COOH  H  O  C  C  O  H


4Propan13dioic acid


O H O


HOOC CH2COOH  H  O  C  C  C  O  H


H


5Butan14dioic acid


O H H O


HOOC CH2 CH2 COOH H O  C  C  C  C O  H


H H


622dichloroethan12dioic acid


HOOCCHCl2 Cl


H  O  C  C  Cl


O H


C LABORATORY AND INDUSTRIAL PREPARATIONOF ALKANOIC ACIDS


In a school laboratory alkanoic acids can be prepared by adding an oxidizing agent HKMnO4 or HK2Cr2O7to the corresponding alkanol then warming


The oxidation converts the alkanol first to an alkanal the alkanoic acid


NB Acidified KMnO4 is a stronger oxidizing agent than acidified K2Cr2O7


General equation


R CH2  OH  O HKMnO4 R CH O  H2Ol


alkanol alkanal


R CH  O  O HKMnO4 R C OOH


alkanal alkanoic acid


Examples


1Ethanol on warming in acidified KMnO4 is oxidized to ethanal then ethanoic acid


CH3 CH2  OH  O HKMnO4 CH3 CH O  H2Ol


ethanol ethanal


CH3 CH  O  O HKMnO4 CH3 C OOH


ethanal ethanoic acid


2Propanol on warming in acidified KMnO4 is oxidized to propanal then propanoic acid


CH3 CH2 CH2  OH  O HKMnO4 CH3 CH2 CH O  H2Ol


propanol propanal


propanal propanoic acid


Industriallylarge scale manufacture of alkanoic acid like ethanoic acid is obtained from


aAlkenes reacting with steam at high temperatures and pressure in presence of phosphoricVacid catalyst and undergo hydrolysis to form alkanols ie


Alkenes  Steamwater  H2PO4 Catalyst Alkanol


The alkanol is then oxidized by air at 5 atmosphere pressure with Manganese IIsulphateVI catalyst to form the alkanoic acid


Alkanol  Air  MnSO4 Catalyst5 atm pressure Alkanoic acid


Example


Ethene is mixed with steam over a phosphoricVacid catalyst300oC temperature and 60 atmosphere pressure to form ethanol


CH2CH2  H2O  CH3 CH2OH


Ethene Ethanol


This is the industrial large scale method of manufacturing ethanol


Ethanol is then oxidized by air at 5 atmosphere pressure with Manganese IIsulphateVI catalyst to form the ethanoic acid


CH3 CH2OH  O  MnSO4 Catalyst5 atm pressure CH3 COOH


Ethanol Ethanoic acid


bAlkynes react with liquid water at high temperatures and pressure in presence of MercuryIIsulphateVIcatalyst and 30 concentrated sulphuricVIacid to form alkanals


Alkyne  Water  MercuryIIsulphateVIcatalyst Alkanal


The alkanal is then oxidized by air at 5 atmosphere pressure with Manganese II sulphateVI catalyst to form the alkanoic acid


Alkanal  airoxygen  ManganeseIIsulphateVIcatalyst Alkanoic acid


Ethyne react with liquid water at high temperature and pressure with Mercury II sulphate VIcatalyst and 30 concentrated sulphuricVIacid to form ethanal


CH  CH  H2O HgSO4 CH3 CH2O


Ethyne Ethanal


This is another industrial large scale method of manufacturing ethanol from large quantities of ethyne found in natural gas


Ethanal is then oxidized by air at 5 atmosphere pressure with Manganese IIsulphateVI catalyst to form the ethanoic acid


CH3 CH2O  O  MnSO4 Catalyst5 atm pressure CH3 COOH


Ethanal Oxygen from air Ethanoic acid


D PHYSICAL AND CHEMICAL PROPERTIES OF ALKANOIC ACIDS


IPhysical properties of alkanoic acids


The table below shows some physical properties of alkanoic acids


From the table note the following


Melting and boiling point decrease as the carbon chain increases due to increase in intermolecular forces of attraction between the molecules requiring more energy to separate the molecules


The density decreases as the carbon chain increases as the intermolecular forces of attraction increases between the molecules making the molecule very close reducing their volume in unit mass


Solubility decreases as the carbon chain increases as the soluble COOH end is shielded by increasing insoluble alkylhydrocarbon chain


Like alkanols alkanoic acids exist as dimmers due to the hydrogen bonds within the molecule ie


II Chemical properties of alkanoic acids


The following experiments shows the main chemical properties of ethanoic alkanoic acid


aEffect on litmus papers


Experiment


Dip both blue and red litmus papers in ethanoic acid Repeat with a solution of succinic acid citric acid oxalic acid tartaric acid and dilute nitricVacid


Sample observations


Explanation


All acidic solutions contains HH3Oaq ions The H H3O aq ions is responsible for turning blue litmus papersolution to red


bpH


Place 2cm3 of ethaoic acid in a test tube Add 2 drops of universal indicator solution and determine its pH Repeat with a solution of succinic acid citric acid oxalic acid tartaric acid and dilute sulphuric VIacid


Explanations


Alkanoic acids are weak acids that partiallypartly dissociate to release few H ions in solution The pH of their solution is thus 456 showing they form weakly acidic solutions when dissolved in water


All alkanoic acid dissociate to releases the H at the functional group in COOH to form the alkanoate ion COO


Mineral acidsSulphuricVIacid NitricVacid and Hydrochloric acid are strong acids that whollyfully dissociate to release many H ions in solution The pH of their solution is thus 123 showing they form strongly acidic solutions when dissolved in waterie


Examples


CH3COOHaq CH3COOaq  Haq


ethanoic acid ethanoate ion few H ion


CH3 CH2COOHaq CH3 CH2COOaq  Haq


propanoic acid propanoate ion few H ion


CH3 CH2 CH2COOHaq CH3 CH2 CH2COOaq  Haq


Butanoic acid butanoate ion few H ion


HOOHaq HOOaq  Haq


methanoic acid methanoate ion few H ion


H2 SO4 aq SO42 aq  2Haq


sulphuricVI acid sulphateVI ion many H ion


HNO3 aq NO3 aq  Haq


nitricV acid nitrateV ion many H ion


cReaction with metals


Experiment


Place about 4cm3 of ethanoic acid in a test tube Put about 1cm length of polished magnesium ribbon Test any gas produced using a burning splint Repeat with a solution of succinic acid citric acid oxalic acid tartaric acid and dilute sulphuric VI acid


Sample observations


Explanation


Metals higher in the reactivity series displace the hydrogen in all acids to evolveproduce hydrogen gas and form a salt Alkanoic acids react with metals with metals to form alkanoates salt and produceevolve hydrogen gas Hydrogen extinguishes a burning splint with a pop soundexplosion Only the Hin the functional group COOH is are displaced and not in the alkyl hydrocarbon chain


Alkanoic acid  Metal  Alkanoate  Hydrogen gas ie


Examples


1 For a monovalent metal with monobasic acid


2R  COOH  2M  2R COOM  2H2g


2For a divalent metal with monobasic acid


2R  COOH  M  R COO 2M  H2g


3For a divalent metal with dibasic acid


HOOCRCOOH M  MOOCRCOOM  H2g


4For a monovalent metal with dibasic acid


HOOCRCOOH 2M  MOOCRCOOM  H2g


5 For mineral acids


iSulphuricVIacid is a dibasic acid


H2 SO4 aq  2M  M2 SO4 aq  H2g


H2 SO4 aq  M  MSO4 aq  H2g


iiNitricV and hydrochloric acid are monobasic acid


HNO3 aq  2M  2MNO3 aq  H2g


HNO3 aq  M  MNO3  2 aq  H2g


1Sodium reacts with ethanoic acid to form sodium ethanoate and produce hydrogen gas


Caution This reaction is explosive


CH3COOH aq  Nas  CH3COONa aq  H2g


Ethanoic acid Sodium ethanoate


2Calcium reacts with ethanoic acid to form calcium ethanoate and produce hydrogen gas


2CH3COOH aq  Cas  CH3COO 2Ca aq  H2g


Ethanoic acid Calcium ethanoate


3Sodium reacts with ethan12dioic acid to form sodium ethan12dioate and produce hydrogen gas


HOOCCOOH 2Na  NaOOC  COONa  H2g


ethan12dioic acid sodium ethan12dioate


Commercial name of ethan12dioic acid is oxalic acid The salt is sodium oxalate


4Magnesium reacts with ethan12dioic acid to form magnesium ethan12dioate and produce hydrogen gas


HOOCRCOOH Mg   OOC  COO Mg  H2g


ethan12dioic acid magnesium ethan12dioate


5Magnesium reacts with


iSulphuricVIacid to form Magnesium sulphateVI


H2 SO4 aq  Mg  MgSO4 aq  H2g


2HNO3 aq  Mg  MNO3  2 aq  H2g


dReaction with hydrogen carbonates and carbonates


Experiment


Place about 3cm3 of ethanoic acid in a test tube Add about 05g  spatula end full of sodium hydrogen carbonatesodium carbonate Test the gas produced using lime water Repeat with a solution of succinic acid citric acid oxalic acid tartaric acid and dilute sulphuric VI acid


Sample observations


All acids react with hydrogen carbonatecarbonate to form salt water and evolveproduce bubbles of carbonIVoxide and water


CarbonIVoxide forms a white precipitate when bubbled in lime waterextinguishes a burning splint


Alkanoic acids react with hydrogen carbonatecarbonate to form alkanoates water and evolveproduce bubbles of carbonIVoxide and water


Alkanoic acid  hydrogen carbonate  alkanoate  water  carbonIVoxide


Alkanoic acid  carbonate  alkanoate  water  carbonIVoxide


Examples


Sodium hydrogen carbonate reacts with ethanoic acid to form sodium ethanoate water and carbonIVoxide gas


CH3COOH aq  NaHCO3 s  CH3COONa aq  H2Ol  CO2 g


Ethanoic acid Sodium ethanoate


2Sodium carbonate reacts with ethanoic acid to form sodium ethanoate water and carbonIVoxide gas


2CH3COOH aq  Na2CO3 s  2CH3COONa aq  H2Ol  CO2 g


3Sodium carbonate reacts with ethan12dioic acid to form sodium ethanoate water and carbonIVoxide gas


HOOCCOOH Na2CO3 s  NaOOC  COONa  H2Ol  CO2 g


ethan12dioic acid sodium ethan12dioate


4Sodium hydrogen carbonate reacts with ethan12dioic acid to form sodium ethanoate water and carbonIVoxide gas


HOOCCOOH 2NaHCO3 s  NaOOC  COONa  H2Ol  2CO2 g


eEsterification


Experiment


Place 4cm3 of ethanol acid in a boiling tube


Add equal volume of ethanoic acid To the mixture add 2 drops of concentrated sulphuricVIacid carefully Warmheat gently on Bunsen flame


Pour the mixture into a beaker containing 50cm3 of water Smell the products Repeat with a solution of succinic acid citric acid oxalic acid tartaric acid and dilute sulphuric VI acid


Sample observations


Explanation


Alkanols react with alkanoic acid to form the sweet smelling homologous series of esters and waterThe reaction is catalysed by concentrated sulphuricVIacid in the laboratory but naturally by sunlight heatEach ester has a characteristic smell derived from the many possible combinations of alkanols and alkanoic acids


Alkanol  Alkanoic acids  Ester  water


Esters derive their names from the alkanol first then alkanoic acids The alkanol becomes an alkyl group and the alkanoic acid becomes alkanoate hence alkylalkanoate eg


Ethanol  Ethanoic acid  Ethylethanoate  Water


Ethanol  Propanoic acid  Ethylpropanoate  Water


Ethanol  Methanoic acid  Ethylmethanoate  Water


Ethanol  butanoic acid  Ethylbutanoate  Water


Propanol  Ethanoic acid  Propylethanoate  Water


Methanol  Ethanoic acid  Methyethanoate  Water


Methanol  Decanoic acid  Methyldecanoate  Water


Decanol  Methanoic acid  Decylmethanoate  Water


During the formation of the ester the O joining the alkanol and alkanoic acid comes from the alkanol


R1 COOH  R2 OH  R1 COO R2  H2O


Examples


1 Ethanol reacts with ethanoic acid to form the ester ethyl ethanoate and water


Ethanol  Ethanoic acid Conc H2SO4 Ethylethanoate  Water


C2H5OH l  CH3COOHl Conc H2SO4  CH3COO C2H5aq H2Ol


CH3CH2OH l CH3COOHl Conc H2SO4  CH3COOCH2CH3aq H2Ol


2 Ethanol reacts with propanoic acid to form the ester ethylpropanoate and water


Ethanol  Propanoic acid Conc H2SO4 Ethylethanoate  Water


C2H5OH l CH3 CH2COOHl Conc H2SO4 CH3CH2COO C2H5aq H2Ol


CH3CH2OH l CH3 CH2COOHl Conc H2SO4


CH3 CH2COOCH2CH3aq H2Ol


3 Methanol reacts with ethanoic acid to form the ester methyl ethanoate and water


Methanol  Ethanoic acid Conc H2SO4 Methylethanoate  Water


CH3OH l  CH3COOHl Conc H2SO4  CH3COO CH3aq H2Ol


4 Methanol reacts with propanoic acid to form the ester methyl propanoate and water


Methanol  propanoic acid Conc H2SO4 Methylpropanoate  Water


CH3OH l CH3 CH2COOHl Conc H2SO4  CH3 CH2COO CH3aq H2Ol


5 Propanol reacts with propanoic acid to form the ester propylpropanoate and water


Propanol  Propanoic acid Conc H2SO4 Ethylethanoate  Water


C3H7OH l CH3 CH2COOHl Conc H2SO4 CH3CH2COO C3H7aq H2Ol


CH3CH2 CH2OH l CH3 CH2COOHl Conc H2SO4  CH3 CH2COOCH2 CH2CH3aq H2Ol


C DETERGENTS


Detergents are cleaning agents that improve the cleaning power properties of waterA detergent therefore should be able to


idissolve substances which water cannot eg grease oil fat


iibe washed away after cleaning


There are two types of detergents


aSoapy detergents


bSoapless detergents


SOAPY DETERGENTS


Soapy detergents usually called soap is long chain salt of organic alkanoic acidsCommon soap is sodium octadecanoate It is derived from reacting concentrated sodium hydroxide solution with octadecanoic acid18 carbon alkanoic acid ie


Sodium hydroxide  octadecanoic acid  Sodium octadecanoate  water


NaOHaq  CH3 CH2 16 COOHaq  CH3 CH2 16 COO  Na aq H2 Ol


Commonly soap can thus be represented


R COO  Na where


R is a long chain alkyl group and COO  Na is the alkanoate ion


In a school laboratory and at industrial and domestic levelsoap is made by reacting concentrated sodium hydroxide solution with esters from animal fat and oil The process of making soap is called saponification During saponification the ester is hydrolyzed by the alkali to form sodium salt soap and glycerolpropan123triol is produced


Fatoilestersodiumpotassium hydroxidesodiumpotassium saltsoap glycerol


FatsOils are esters with fatty acids and glycerol parts in their structure


When boiled with concentrated sodium hydroxide solution NaOH


iNaOH ionizesdissociates into Na and OH ions


iifatoil split into three C17H35COO and one CH2 CH CH2


iii the three Na combine with the three C17H35COO to form the salt C17H35COO Na


ivthe three OHions combine with the CH2 CH CH2 to form an alkanol with three functional groups CH2 OH CH OH CH2 OHpropan123triol


C17H35COOCH2 CH2OH


C17H35COOCH NaOH  3 C17H35COO Na  CHOH


Ester Alkali Soap glycerol


Generally


CnH2n1COOCH2 CH2OH


CnH2n1COOCH NaOH  3 CnH2n1COO Na  CHOH


R  COOCH2 CH2OH


R  COOCH NaOH  3RCOO Na  CHOH


R COOCH2 CH2OH


During this process a little sodium chloride is added to precipitate the soap by reducing its solubility This is called salting out


The soap is then added colouring agents perfumes and herbs of choice


School laboratory preparation of soap


Place about 40 g of fatty animal fatbeefmeat in 100cm3 beaker Add about 15cm3 of 40M sodium hydroxide solution Boil the mixture for about 15minutesStir the mixture Add about 50cm3 of distilled water as you boil to make up for evaporation Boil for about another 15minutesAdd about four spatula end full of pure sodium chloride crystals Continue stirring for another five minutes Allow to cool Filter of decant and wash off the residue with distilled water Transfer the clean residue into a dry beaker Preserve


The action of soap


Soapy detergents


iact by reducing the surface tension of water by forming a thin layer on top of the water


iiis made of a nonpolar alkyl hydrocarbon tail and a polar COONa head The nonpolar alkyl hydrocarbon tail is hydrophobic water hating and thus does not dissolve in water It dissolves in nonpolar solvent like grease oil and fat The polar COONa head is hydrophilic water lovingand thus dissolve in water When washing with soapy detergent the nonpolar tail of the soapy detergent surrounddissolve in the dirt on the garment greaseoil while the polar head dissolve in water


Through mechanical agitationstirringsqeezingrubbingbeatingkneading some grease is dislodgedlifted of the surface of the garment It is immediately surrounded by more soap molecules It float and spread in the water as tiny droplets that scatter light in form of emulsion making the water cloudy and shinny It is removed from the garment by rinsing with fresh water The repulsion of the soap head prevent ensure the droplets do not mix Once removed the dirt molecules cannot be redeposited back because it is surrounded by soap molecules


Advantages and disadvantages of using soapy detergents


Soapy detergents are biodegradable They are acted upon by bacteria and rot They thus do not cause environmental pollution


Soapy detergents have the disadvantage in that


ithey are made from fat and oils which are better eaten as food than make soap


iiforms an insoluble precipitate with hard water called scum Scum is insoluble calcium octadecanoate and Magnesium octadecanoate formed when soap reacts with Ca2 and Mg2 present in hard water


Chemical equation


2C17H35COO Na aq  Ca2aq  C17H35COO Ca2 s  2Naaq


insoluble Calcium octadecanotescum


2C17H35COO Na aq  Mg2aq  C17H35COO Mg2 s  2Naaq


insoluble Magnesium octadecanotescum


This causes wastage of soap


Potassium soaps are better than Sodium soap Potassium is more expensive than sodium and thus its soap is also more expensive


bSOAPLESS DETERGENTS


Soapless detergent usually called detergent is a long chain salt fromed from byproducts of fractional distillation of crude oilCommonly used soaps include


iwashing agents


iitoothpaste


iiiemulsifierswetting agentsshampoo


Soapless detergents are derived from reacting


iconcentrated sulphuricVIacid with a long chain alkanol eg Octadecanol18 carbon alkanol to form alkyl hydrogen sulphateVI


Alkanol  Conc sulphuricVIacid  alkyl hydrogen sulphateVI  Water


R OH  H2SO4  R OSO3H  H2O


iithe alkyl hydrogen sulphateVI is then neutralized with sodiumpotassium hydroxide to form sodiumpotassium alkyl hydrogen sulphateVI


Sodiumpotassium alkyl hydrogen sulphateVI is the soapless detergent


alkyl hydrogen  Potassiumsodium  Sodiumpotassium  Water


sulphateVI hydroxide alkyl hydrogen sulphateVI


R OSO3H  NaOH  R OSO3 Na  H2O


Example


Step I  Reaction of Octadecanol with ConcH2SO4


C17H35CH2OH aq  H2SO4  C17H35CH2O SO3 H aq  H2O l


octadecanol  sulphuricVIacid  Octadecyl hydrogen sulphateVI  water


Step II Neutralization by an alkali


C17H35CH2O SO3 H aq  NaOH  C17H35CH2O SO3 Na aq  H2O l


Octadecyl hydrogen  sodiumpotassium  sodiumpotassium octadecylWater


sulphateVI hydroxide hydrogen sulphateVI


School laboratory preparation of soapless detergent


Place about 20g of olive oil in a 100cm3 beaker Put it in a trough containing ice cold water


Add dropwise carefully 18M concentrated sulphuricVIacid stirring continuously into the olive oil until the oil turns brownAdd 30cm3 of 6M sodium hydroxide solutionStirThis is a soapless detergent


The action of soapless detergents


The action of soapless detergents is similar to that of soapy detergentsThe soapless detergents contain the hydrophilic head and a long hydrophobic tail ie


vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvCOONa


vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvOSO3 Na


long hydrophobic nonpolar alkyl tail hydrophilicpolarionic head


The tail dissolves in fatgreaseoil while the ionicpolarionic head dissolves in water


The tail stick to the dirt which is removed by the attraction of water molecules and the polarionichydrophilic head by mechanical agitation squeezingkneading beatingrubbingscrubbingscatching


The suspended dirt is then surrounded by detergent molecules and repulsion of the anion head preventing the dirt from sticking on the material garment


The tiny droplets of dirt emulsion makes the water cloudy On rinsing the cloudy emulsion is washed away


Advantages and disadvantages of using soapless detergents


Soapless detergents are nonbiodegradable unlike soapy detergents


They persist in water during sewage treatment by causing foaming in rivers lakes and streams leading to marine aquatic death


Soapless detergents have the advantage in that they


ido not form scum with hard water


iiare cheap to manufacturebuying


iiiare made from petroleum products but soapis made from fatsoil for human consumption


Sample revision questions


1 Study the scheme below


aIdentify the process


Saponification


bFats and oils are esters Write the formula of the a common structure of ester


cWrite a balanced equation for the reaction taking place during boiling


C17H35COOCH2 CH2OH


C17H35COOCH 3NaOH  3 C17H35COO Na  CHOH


Ester Alkali Soap glycerol


dGive the IUPAC name of


iResidue X


Potassium octadecanoate


iiFiltrate Y


eGive one use of fitrate Y


Making paint


fWhat is the function of sodium chloride


To reduce the solubility of the soap hence helping in precipitating it out


gExplain how residue X helps in washing


Has a nonpolar hydrophobic tail that dissolves in dirtgrease oilfat


Has a polar ionic hydrophilic head that dissolves in water


From mechanical agitationthe dirt is plucked out of the garment and surrounded by the tail end preventing it from being deposited back on the garment


hState one


iadvantage of continued use of residue X on the environment


Is biodegradable and thus do not pollute the environment


iidisadvantage of using residue X


Uses fatoil during preparationmanufacture which are better used for human consumption


iResidue X was added dropwise to some waterThe number of drops used before lather forms is as in the table below


iState and explain which sample of water is


I Soft


Sample B Very little soap is used and no effect on amount of soap even on boilingheating


II Permanent hard


Sample C  A lot of soap is used and no effect on amount of soap even on boilingheating Boiling does not remove permanent hardness of water


III Temporary hard


Sample A  A lot of soap is used before boiling Very little soap is used on boilingheating Boiling remove temporary hardness of water


iiWrite the equation for the reaction at water sample C


Chemical equation


2C17H35COO K aq  CaSO4aq  C17H35COO Ca2 s  K2SO4aq


insoluble Calcium octadecanotescum


Ionic equation


2C17H35COO K aq  Ca2aq  C17H35COO Ca2 s  2Kaq


2C17H35COO K aq  MgSO4aq  C17H35COO Mg2 s  K2SO4aq


2C17H35COO K aq  Mg2aq  C17H35COO Mg2 s  2Kaq


insoluble Magnesium octadecanotescum


iiiWrite the equation for the reaction at water sample A before boiling


2C17H35COO K aq  CaHCO3aq C17H35COO Ca2 s  2KHCO3 aq


2C17H35COO K aq  MgHCO3aq C17H35COO Mg2 s  2KHCO3 aq


ivExplain how water becomes hard


Natural or rain water flowing passing through rocks containing calcium chalk gypsum limestoneand magnesium compounds dolomitedissolve them to form soluble Ca2 and Mg2 ions that causes water hardness


vState two useful benefits of hard water


Used in bone and teeth formation


Coral polyps use hard water to form coral reefs


Snails use hard water to make their shells


2Study the scheme below and use it to answer the questions that follow


aIdentify


ibrown solid A


Alkyl hydrogen sulphateVI


iisubstance B


Sodium alkyl hydrogen sulphateVI


bWrite a general formula of


iSubstance A


O


ROS O3 H  R O  S  O  H


iiSubstance B O


ROS O3  Na R O  S  O  Na


cState one


i advantage of continued use of substance B


Does not form scum with hard water


Is cheap to make


Does not use food for human as a raw material


iidisadvantage of continued use of substance B


Is nonbiodegradable therefore do not pollute the environment


dExplain the action of B during washing


Has a nonpolar hydrocarbon long tail that dissolves in dirtgreaseoilfat


Has a polarionic hydrophilic head that dissolves in water


Through mechanical agitation the dirt is plucked removed from the garment and surrounded by the tail end preventing it from being deposited back on the garment


e Ethene was substituted for olive oil in the above process Write the equation and name of the new products A and B


Product A


Ethene  SulphuricVIacid  Ethyl hydrogen sulphateVI


H2CCH2  H2SO4  H3C  CH2 OSO3H


Product B


Ethyl hydrogen sulphateVI  sodium hydroxide  sodium Ethyl  Water


hydrogen sulphateVI


H3C  CH2 OSO3H  NaOH  H3C  CH2 OSO3Na  H2O


fEthanol can also undergo similar reactions forming new products A and BShow this using a chemical equation


Ethanol  SulphuricVIacid Ethyl hydrogen sulphateVI  water


H3CCH2OH  H2SO4  H3C  CH2 OSO3H  H2O


3Below is part of a detergent


H3C  CH2 16  O  SO3  K


aWrite the formular of the polar and nonpolar end


Polar end


H3C  CH2 16


Nonpolar end


O  SO3  K


bIs the molecule a soapy or saopless detergent


Soapless detergent


cState one advantage of using the above detergent


does not form scum with hard water


is cheap to manufacture


4The structure of a detergent is


H H H H H H H H H H H H H


H C C CC C C C C C C C C C COONa


a Write the molecular formula of the detergent 1mk


b What type of detergent is represented by the formula 1mk


Soapy detergent


c When this type of detergent is used to wash linen in hard water spots marks are left on the linen Write the formula of the substance responsible for the spots CH3CH212COO2Ca2  CH3CH212COO2Mg2


D POLYMERS AND FIBRES


Polymers and fibres are giant molecules of organic compounds Polymers and fibres are formed when small molecules called monomers join together to form large molecules called polymers at high temperatures and pressures This process is called polymerization


Polymers and fibres are either


aNatural polymers and fibres


bSynthetic polymers and fibres


Natural polymers and fibres are found in living thingsplants and animals Natural polymersfibres include


proteinspolypeptides making amino acids in animals


cellulose that make cottonwoolpaper and silk


Starch that come from glucose


Fats and oils


Rubber from latex in rubber trees


Synthetic polymers and fibres are manmade They include


polyethene


polychloroethene


polyphenylethenepolystyrene


TeryleneDacron


Perspexartificial glass


Synthetic polymers and fibres have the following characteristic advantages over natural polymers


1 They are light and portable


2 They are easy to manufacture


3 They can easily be molded into shape of choice


4 They are resistant to corrosion water air  acids bases and salts


5 They are comparatively cheap affordable colourful and aesthetic


Synthetic polymers and fibres however have the following disadvantages over natural polymers


They are nonbiodegradable and hence cause environmental pollution during disposal


They give out highly poisonous gases when burnt like chlorinecarbonIIoxide


Some on burning produce CarbonIVoxide CarbonIVoxide is a green house gas that cause global warming


Compared to some metals they are poor conductors of heatelectricity and have lower tensile strength


To reduce environmental pollution from synthetic polymers and fibres the followitn methods of disposal should be used


1Recycling Once produced all synthetic polymers and fibres should be recycled to a new product This prevents accumulation of the synthetic polymers and fibres in the environment


2Production of biodegradable synthetic polymers and fibres that rot away


There are two types of polymerization


aaddition polymerization


bcondensation polymerization


Addition polymerization is the process where a small unsaturated monomer alkene  molecule join together to form a large saturated molecule Only alkenes undergo addition polymerization


Addition polymers are named from the alkenemonomer making the polymer and adding the prefix poly before the name of monomer to form a polyalkene


During addition polymerization


ithe double bond in alkenes break


iifree radicals are formed


iiithe free radicals collide with each other and join to form a larger molecule The more collisions the larger the molecule


Examples of addition polymerization


1Formation of Polyethene


Polyethene is an addition polymer formed when ethene moleculemonomer join together to form a large moleculepolymer at high temperatures and pressure


During polymerization


imany molecules are brought nearer to each other by the high pressurewhich reduces the volume occupied by reacting paticles


H H H H H H H H


C  C  C  C  C  C  C  C


Ethene  Ethene  Ethene  Ethene


iithe double bond joining the ethane molecule break to free readicals


Ethene radical  Ethene radical  Ethene radical  Ethene radical


iiithe free radicals collide with each other and join to form a larger molecule


H H H H H H H H lone pair of electrons


Lone pair of electrons can be used to join more monomers to form longer polyethene


Polyethene molecule can be represented as


H H H H H H H H extension of


moleculepolymer


Since the molecule is a repetition of one monomer then the polymer is


H H


C  C n


Where n is the number of monomers in the polymer The number of monomers in the polymer can be determined from the molar mass of the polymer and monomer from the relationship


Number of monomersrepeating units in monomer  Molar mass polymer


Molar mass monomer


Examples


Polythene has a molar mass of 4760Calculate the number of ethene molecules in the polymerC120 H10


Number of monomersrepeating units in polyomer  Molar mass polymer


Molar mass ethene C2H4  28 Molar mass polyethene  4760


Substituting 4760  170 ethene molecules


The commercial name of polyethene is polythene It is an elastic tough transparent and durable plastic Polythene is used


iin making plastic bag


iibowls and plastic bags


iiipackaging materials


2Formation of Polychlorethene


Polychloroethene is an addition polymer formed when chloroethene moleculemonomer join together to form a large moleculepolymer at high temperatures and pressure


During polymerization


imany molecules are brought nearer to each other by the high pressurewhich reduces the volume occupied by reacting particles


H H H H H H H H


C  C  C  C  C  C  C  C


H Cl H Cl H Cl H Cl


chloroethene  chloroethene  chloroethene  chloroethene


iithe double bond joining the chloroethene molecule break to free radicals


H H H H H H H H lone pair of electrons


Lone pair of electrons can be used to join more monomers to form longer polychloroethene


Polychloroethene molecule can be represented as


H H H H H H H H extension of


moleculepolymer


H H


C  C n


H Cl


Examples


Polychlorothene has a molar mass of 4760Calculate the number of chlorethene molecules in the polymerC120 H10Cl355


Molar mass monomer


Molar mass ethene C2H3Cl  625 Molar mass polyethene  4760


Substituting 4760  7716  77 polychloroethene moleculeswhole number


The commercial name of polychloroethene is polyvinylchloridePVC It is a tough nontransparent and durable plastic PVC is used


iin making plastic rope


iiwater pipes


iiicrates and boxes


3Formation of Polyphenylethene


Polyphenylethene is an addition polymer formed when phenylethene moleculemonomer join together to form a large moleculepolymer at high temperatures and pressure


During polymerization


H H H H H H H H


C  C  C  C  C  C  C  C


H C6H5 H C6H5 H C6H5 H C6H5


phenylethene  phenylethene  phenylethene  phenylethene


iithe double bond joining the phenylethene molecule break to free radicals


iiithe free radicals collide with each other and join to form a larger molecule


H H H H H H H H lone pair of electrons


Lone pair of electrons can be used to join more monomers to form longer polyphenylethene


Polyphenylethene molecule can be represented as


Since the molecule is a repetition of one monomer then the polymer is


H H


C  C n


H C6H5


Examples


Polyphenylthene has a molar mass of 4760Calculate the number of phenylethene molecules in the polymerC120 H10


Number of monomersrepeating units in monomer  Molar mass polymer


Molar mass monomer


Molar mass ethene C8H8  104 Molar mass polyethene  4760


Substituting 4760  457692 45 polyphenylethene moleculeswhole number


The commercial name of polyphenylethene is polystyrene It is a very light durable plastic Polystyrene is used


iin making packaging material for carrying delicate items like computers radioncalculators


iiceiling tiles


iiiclothe linings


4Formation of Polypropene


Polypropene is an addition polymer formed when propene moleculemonomer join together to form a large moleculepolymer at high temperatures and pressure


During polymerization


imany molecules are brought nearer to each other by the high pressurewhich reduces the volume occupied by reacting particles


H H H H H H H H


C  C  C  C  C  C  C  C


H CH3 H CH3 H CH3 H CH3


propene  propene  propene  propene


H H H H H H H H lone pair of electrons


Lone pair of electrons can be used to join more monomers to form longer propene


propene molecule can be represented as


H H


C  C n


H CH3


Examples


Polypropene has a molar mass of 4760Calculate the number of propene molecules in the polymerC120 H10


Molar mass monomer


Molar mass propene C3H8  44 Molar mass polyethene  4760


Substituting 4760  1081818 108 propene moleculeswhole number


iiceiling tiles


iiiclothe linings


5Formation of Polytetrafluorothene


Polytetrafluorothene is an addition polymer formed when tetrafluoroethene moleculemonomer join together to form a large moleculepolymer at high temperatures and pressure


During polymerization


F F F F F F F F


C  C  C  C  C  C  C  C


tetrafluoroethene  tetrafluoroethene tetrafluoroethene tetrafluoroethene


iithe double bond joining the tetrafluoroethene molecule break to free radicals


iiithe free radicals collide with each other and join to form a larger molecule


F F F F F F F F lone pair of electrons


Lone pair of electrons can be used to join more monomers to form longer polytetrafluoroethene


polytetrafluoroethene molecule can be represented as


F F F F F F F F extension of


moleculepolymer


Since the molecule is a repetition of one monomer then the polymer is


F F


C  C n


Examples


Polytetrafluorothene has a molar mass of 4760Calculate the number of tetrafluoroethene molecules in the polymerC120 F19


Number of monomersrepeating units in monomer  Molar mass polymer


Molar mass monomer


Molar mass ethene C2F4  625 Molar mass polyethene  4760


Substituting 4760  7716  77 polychloroethene moleculeswhole number


The commercial name of polytetrafluorethenePTFE is TeflonPTFE It is a tough nontransparent and durable plastic PVC is used


iin making plastic rope


iiwater pipes


iiicrates and boxes


5Formation of rubber from Latex


Natural rubber is obtained from rubber trees


During harvesting an incision is made on the rubber tree to produce a milky white substance called latex


Latex is a mixture of rubber and lots of water


The latex is then added an acid to coagulate the rubber


Natural rubber is a polymer of 2methylbut13diene


H CH3 H H


CH2C CH3 CH  CH2 H  C  C  C  C  H


During natural polymerization to rubber one double CC bond break to self add to another molecule The double bond remaining move to carbon 2 thus


H CH3 H H H CH3 H H


C  C  C  C  C  C  C  C


H H H H


Generally the structure of rubber is thus


C  C  C  C n


H H


Pure rubber is soft and sticky It is used to make erasers car tyres Most of it is vulcanized Vulcanization is the process of heating rubber with sulphur to make it hardertougher


During vulcanization the sulphur atoms form a cross link between chains of rubber moleculespolymers This decreases the number of CC double bonds in the polymer


H S H H S H


H CH3 S H H CH3 S H


H H H H H H


Vulcanized rubber is used to make tyres shoes and valves


6Formation of synthetic rubber


Synthetic rubber is able to resist action of oilabrasion and organic solvents which rubber cannot


Common synthetic rubber is a polymer of 2chlorobut13diene


H Cl H H


CH2C Cl CH  CH2 H  C  C  C  C  H


During polymerization to synthetic rubber one double CC bond is broken to self add to another molecule The double bond remaining move to carbon 2 thus


H Cl H H H Cl H H


C  C  C  C  C  C  C  C


H H H H


C  C  C  C n


H H


Rubber is thus strengthened through vulcanization and manufacture of synthetic rubber


bCondensation polymerization


Condensation polymerization is the process where two or more small monomers join together to form a larger molecule by eliminationremoval of a simple molecule usually water


Condensation polymers acquire a different name from the monomers because the two monomers are two different compounds


During condensation polymerization


ithe two monomers are brought together by high pressure to reduce distance between them


iimonomers realign themselves at the functional group


iiifrom each functional group an element is removed so as to form simple molecule of usually H2OHCl


ivthe two monomers join without the simple molecule of H2OHCl


Examples of condensation polymerization


1Formation of Nylon66


Method 1 Nylon66 can be made from the condensation polymerization of hexan16dioic acid with hexan16diamineAmines are a group of homologous series with a general formula RNH2 and thus NH2 as the functional group


During the formation of Nylon66


ithe two monomers are brought together by high pressure to reduce distance between them and realign themselves at the functional groups


O O H H


H O  C  CH2  4  C  O  H  H N  CH2 6  N  H


iiifrom each functional group an element is removed so as to form a molecule of H2O and the two monomers join at the linkage


H O  C  CH2  4  C  N  CH2 6  N  H  H 2O


Polymer bond linkage


Nylon66 derive its name from the two monomers each with six carbon chain


Method 2 Nylon66 can be made from the condensation polymerization of hexan16dioyl dichloride with hexan16diamine


Hexan16dioyl dichloride belong to a group of homologous series with a general formula ROCl and thus OCl as the functional group


The ROCl is formed when the OH in ROOHalkanoic acid is replaced by ClchlorineHalogen


Cl  C  CH2  4  C  Cl  H N  CH2 6  N  H


iiifrom each functional group an element is removed so as to form a molecule of HCl and the two monomers join at the linkage


Cl  C  CH2  4  C  N  CH2 6  N  H  HCl


The two monomers each has six carbon chain hence the name nylon66


The commercial name of Nylon66 is Nylon It is a a tough elastic and durable plastic It is used to make clothes plastic ropes and carpets


2Formation of Terylene


Method 1 Terylene can be made from the condensation polymerization of ethan12diol with benzene14dicarboxylic acid


Benzene14dicarboxylic acid a group of homologous series with a general formula RCOOH where R is a ring of six carbon atom called Benzene ring The functional group is COOH


During the formation of Terylene


O O


H O  C  C6H5  C  O  H  H O  CH2 CH2  O  H


H O  C  C6H5  C  O  CH2 6  N  H  H 2O


Polymer bond linkage of terylene


Method 2 Terylene can be made from the condensation polymerization of benzene14dioyl dichloride with ethan12diol


Benzene14dioyl dichloride belong to a group of homologous series with a general formula ROCl and thus OCl as the functional group and R as a benzene ring


The ROCl is formed when the OH in ROOH is replaced by ClchlorineHalogen


Cl  C  C5H5  C  Cl  H O  CH2 CH2  O  H


Cl  C  C5H5  C  O  CH2 CH2  O  H  HCl


The commercial name of terylene is Polyester polyster It is a a tough elastic and durable plastic It is used to make clothes plastic ropes and sails and plastic model kits


Practice questions Organic chemistry


1 A student mixed equal volumes of Ethanol and butanoic acid He added a few drops of concentrated Sulphuric VI acid and warmed the mixture


i Name and write the formula of the main products Name


Formula


ii Which homologous series does the product named in i above belong


2 The structure of the monomer phenyl ethene is given below


a Give the structure of the polymer formed when four of the monomers are added together


b Give the name of the polymer formed in a above


3 Explain the environmental effects of burning plastics in air as a disposal method 4 Write chemical equation to represent the effect of heat on ammonium carbonate


5 Sodium octadecanoate has a chemical formula CH3CH26 COONa which is used as soap


Explain why a lot of soap is needed when washing with hard water


6 A natural polymer is made up of the monomer


a Write the structural formula of the repeat unit of the polymer b When 50 x 105 moles of the polymer were hydrolysed 0515g of the monomer were obtained


Determine the number of the monomer molecules in this polymer


C  12 H  1 N  14 O 16


7 The formula below represents active ingredients of two cleansing agents A and B


Which one of the cleansing agents would be suitable to be used in water containing magnesium hydrogen carbonate Explain


8 Study the polymer below and use it to answer the questions that follow


a Give the name of the monomer and draw its structures b Identify the type of polymerization that takes place c State one advantage of synthetic polymers


9 Ethanol and Pentane are miscible liquids Explain how water can be used to separate a mixture of ethanol and pentane


a What is absolute ethanol


i Plot a graph of volume of oxygen gas against time ii Determine the rate of reaction at time 156 seconds iii From the graph find the time taken for 18cm3 of oxygen to be produced iv Write a chemical equation to show how hydrogen peroxide decomposes in the presence of manganese IV Oxide


b The diagram below shows how a Leclanche Dry cell appears


i What is the function of MnO2 in the cell above


ii Write the equation of a reaction that occurs at the cathode


iii Calculate the mass of Zinc that is consumed when a current of 01amperes flows through the above cell for 30minutes 1F 96500c Zn 65


12 a Give the IUPAC names of the following compounds


i CH3COOCH2CH3


ii


b The structure below shows some reactions starting with ethanol Study it and answer


the questions that follow


i Write the formula of the organic compounds P and S


ii Name the type of reaction the reagents and condition for the reactions in the following steps


I Step I


II Step II


III Step III


iii Name reagent R  iv Draw the structural formula of T and give its name


v I Name compound U


II If the relative molecular mass of U is 42000 determine the value of n C12 H1


c State why C2H4 burns with a more smoky flame than C2H6 13 a State two factors that affect the properties of a polymer b Name the compound with the formula below  CH3CH2CH2ONa


c Study the scheme below and use it to answer the questions that follow


i Name the following compounds


I Product T  II K  ii State one common physical property of substance G


iii State the type of reaction that occurred in step J


iv Give one use of substance K


v Write an equation for the combustion of compound P vi Explain how compounds CH3CH2COOH and CH3CH2CH2OH can be distinguished chemically


vii If a polymer K has relative molecular mass of 12600 calculate the value of n H1 C 12


14 Study the scheme given below and answer the questions that follow


a i Name compound P


ii Write an equation for the reaction between CH3CH2COOH and Na2CO3 b State one use of polymer Q


c Name one oxidising agent that can be used in step II


d A sample of polymer Q is found to have a molecular mass of 4200 Determine the number of


monomers in the polymer H  1 C  12


e Name the type of reaction in step I


f State one industrial application of step III


gState how burning can be used to distinguish between propane and propyne Explain your


answer


h 1000cm3 of ethene C2H4 burnt in oxygen to produce Carbon II Oxide and water vapour


Calculate the minimum volume of air needed for the complete combustion of ethene


Air contains 20 by volume of oxygen


15 a Study the schematic diagram below and answer the questions that follow


i Identify the following


Substance Q


Substance R


Gas P


ii Name


Step 1


Step 4


iii Draw the structural formula of the major product of step 5 iv State the condition and reagent in step 3 16 Study the flow chart below and answer the questions that follow


a i Name the following organic compounds


M


L ii Name the process in step


Step 2


iii Identify the reagent P and Q


iv Write an equation for the reaction between CH3CH2CH2OH and sodium 17 a Give the names of the following compounds


i CH3CH2CH2CH2OH


ii CH3CH2COOH


iii CH3C  O CH2CH3


18 Study the scheme given below and answer the questions that follow


i Name the reagents used in


Step I


Step II


Step III


ii Write an equation to show products formed for the complete combustion of CH  CH


iii Explain one disadvantage of continued use of items made from the compound formed in step III


19 A hydrated salt has the following composition by mass Iron 202  oxygen 230 sulphur 115 water 453


i Determine the formula of the hydrated salt Fe56 S32 O16 H11 ii 695g of the hydrated salt in ci above were dissolved in distilled water and the total volume made to 250cm3 of solution Calculate the concentration of the resulting salt solution in moles per litre Given that the molecula mass of the salt is 278


20 Write an equation to show products formed for the complete combustion of CH  CH


21 Give the IUPAC name for each of the following organic compounds


i CH3  CH  CH2  CH3


OH


iiCH3  CH  CH2  CH2  CH3


22 The structure below represents a cleansing agent


O


R  S  ONa


a State the type of cleansing agent represented above b State one advantage and one disadvantage of using the above cleansing agent


23 The structure below shows part of polymer Use it to answer the questions that follow


CH3 CH3 CH3


CH  CH2  CH CH2  CH  CH2


a Derive the structure of the monomer


b Name the type of polymerization represented above


24 The flow chart below represents a series of reactions starting with ethanoic acid


a Identify substances A and B


b Name the process I


25 a Write an equation showing how ammonium nitrate may be prepared starting with ammonia gas


b Calculate the maximum mass of ammonium nitrate that can be prepared using 53kg of ammonia H1 N14 O16


26 a What is meant by the term esterification


b Draw the structural formulae of two compounds that may be reacted to form ethylpropanoate


27 a Draw the structure of pentanoic acid


b Draw the structure and give the name of the organic compound formed when ethanol reacts with pentanoic acid in presence of concentrated sulphuric acid


28 The scheme below shows some reactions starting with ethanol Study it and answer the questions


that follow


i Name and draw the structure of substance Q


ii Give the names of the reactions that take place in steps 2 and 4 iii What reagent is necessary for reaction that takes place in step 3


29 Substances A and B are represented by the formulae ROH and RCOOH respectively


They belong to two different homologous series of organic compounds If both A and B


react with potassium metal


a Name the common product produced by both b State the observation made when each of the samples A and B are reacted with sodium hydrogen carbonate


i A


ii B


30 Below are structures of particles Use it to answer questions that follow In each case only electrons in the outermost energy level are shown


key


P  Proton


N  Neutron


X  Electron


a Identify the particle which is an anion


31 Plastics and rubber are extensively used to cover electrical wires


a What term is used to describe plastic and rubbers used in this way b Explain why plastics and rubbers are used this way


32 The scheme below represents the manufacture of a cleaning agent X


a Draw the structure of X and state the type of cleaning agent to which X belong b State one disadvantage of using X as a cleaning agent


33 Y grams of a radioactive isotope take 120days to decay to 35grams The halflife period of the isotope is 20days


a Find the initial mass of the isotope


b Give one application of radioactivity in agriculture


34 The structure below represents a polymer Study and answer the questions that follow


i Name the polymer above ii Determine the value of n if giant molecule had relative molecular mass of 4956


35 RCOONa and RCH2OSO3Na are two types of cleansing agents


i Name the class of cleansing agents to which each belongs


ii Which one of these agents in i above would be more suitable when washing with water from the Indian ocean Explain


iii Both sulphur IV oxide and chlorine are used bleaching agents Explain the difference in their bleaching properties


36 The formula given below represents a portion of a polymer


a Give the name of the polymer


b Draw the structure of the monomer used to manufacture the polymer


THE MOLE


aGas laws


1 Matter is made up of small particle in accordance to Kinetic Theory of matter


Naturally there are basically three states of matter Solid Liquid and gas


iA solid is made up of particles which are very closely packed with a definitefixed shape and fixeddefinite volume occupies definite space It has a very high density


ii A liquid is made up of particles which have some degree of freedom It thus has no definitefixed shape It takes the shape of the container it is put A liquid has fixeddefinite volumeoccupies definite space


iiiA gas is made up of particles free from each other It thus has no definite fixed shape It takes the shape of the container it is put It has no fixeddefinite volumeoccupies every space in a container


2Gases are affected by physical conditions There are two physical conditions


iTemperature


iiPressure


3 The SI unit of temperature is KelvinK


Degrees CelsiusCentigradeoC are also used


The two units can be interconverted from the relationship


oC  273 K


K 273  oC


Practice examples


1 Convert the following into Kelvin


i O oC


oC  273  K substituting  O oC  273  273 K


ii 273 oC


oC  273  K substituting  273oC  273  0 K


iii 25 oC


oC  273  K substituting  25 oC  273  298 K


iv 100 oC


oC  273  K substituting  100 oC  273  373 K


2 Convert the following into degrees CelsiusCentigradeoC


i 10 K


K 273  oC substituting 10  273  263 oC


ii i 1 K


K 273  oC substituting 1  273  272 oC


iii 110 K


K 273  oC substituting 110  273  163 oC


iv 24 K


K 273  oC substituting 24  273  297 oC


The standard temperature is 273K  0 oC


The room temperature is assumed to be 298K  25oC


4 The SI unit of pressure is PascalPa  Newton per metre squared Nm2  Millimeters of mercurymmHg centimeters of mercurycmHg and atmospheres are also commonly used


The units are not interconvertible but PascalsPa are equal to Newton per metre squaredNm2


The standard pressure is the atmospheric pressure


Atmospheric pressure is equal to about


i101325 Pa


ii101325 Nm2


iii760 mmHg


iv76 cmHg


vone atmosphere


5 Molecules of gases are always in continuous random motion at high speed This motion is affected by the physical conditions of temperature and pressure


Physical conditions change the volume occupied by gases in a closed system


The effect of physical conditions of temperature and pressure was investigated and expressed in both Boyles and Charles laws


6 Boyles law states that


the volume of a fixed mass of a gas is inversely proportional to the pressure at constantfixed temperature


Mathematically


Volume  1 Fixed constant Temperature


Pressure


V  1 Fixed constant T ie PV  Constantk


P


From Boyles law  an increase in pressure of a gas cause a decrease in volume ie doubling the pressure cause the volume to be halved


Graphically therefore a plot of volumeV against pressure P produces a curve


V


Graphically a plot of volumeV against inversereciprocal of pressure 1p produces a straight line


For two gases then P1 V1  P2 V2


P1  Pressure of gas 1


V1  Volume of gas 1


P2  Pressure of gas 2


V2  Volume of gas 2


Practice examples


1 A fixed mass of gas at 102300Pa pressure has a volume of 25cm3Calculate its volume if the pressure is doubled


Working


P1 V1  P2 V2 Substituting 102300 x 25  102300 x 2 x V2


V2  102300 x 25  125cm3


102300 x 2


2 Calculate the pressure which must be applied to a fixed mass of 100cm3 of Oxygen for its volume to triple at 100000Nm2


P1 V1  P2 V2 Substituting 100000 x 100  P2 x 100 x 3


V2  100000 x 100  333333333 Nm2


100 x 3


3A 60cm3 weather ballon full of Hydrogen at atmospheric pressure of 101325Pa was released into the atmosphere Will the ballon reach stratosphere where the pressure is 90000Pa


P1 V1  P2 V2 Substituting 101325 x 60  90000 x V2


V2  101325 x 60  6755 cm3


The new volume at 6755 cm3 exceed ballon capacity of 6000 cm3It will burst before reaching destination


7Charles law states thatthe volume of a fixed mass of a gas is directly proportional to the absolute temperature at constantfixed pressure


Mathematically


Volume  Pressure Fixed constant pressure


V  T Fixed constant P ie V  Constantk


T


From Charles law  an increase in temperature of a gas cause an increase in volume ie doubling the temperature cause the volume to be doubled


Gases expandincrease by 1273 by volume on heatingGases contactdecrease by 1273 by volume on cooling at constantfixed pressure


The volume of a gas continue decreasing with decrease in temperature until at 273oC 0 K the volume is zero ie there is no gas


This temperature is called absolute zero It is the lowest temperature at which a gas can exist


Graphically therefore a plot of volumeV against TemperatureT in


ioC produces a straight line that is extrapolated to the absolute zero of 273oC


V


273oC 0oC


ToC


iiKelvinK produces a straight line from absolute zero of O Kelvin


0 TKelvin


For two gases then V1  V2


T1 T2


T1  Temperature in Kelvin of gas 1


V1  Volume of gas 1


T2  Temperature in Kelvin of gas 2


V2  Volume of gas 2


Practice examples


1 500cm3 of carbonIVoxide at 0oC was transfered into a cylinder at 4oC If the capacity of the cylinder is 450 cm3explain what happened


V1  V2 substituting 500  V2


T1 T2 0 273 4 273


500 x 4 x 273  492674cm3


0  273


The capacity of cylinder 500cm3 is less than new volume492674cm3


7326cm3500492674cm3of carbonIVoxide gas did not fit into the cylinder


2 A mechanic was filling a deflated tyre with air in his closed garage using a hand pump The capacity of the tyre was 40000cm3 at room temperature He rolled the tyre into the car outside The temperature outside was 30oCExplain what happens


V1  V2 substituting 40000  V2


T1 T2 25 273 30 273


40000 x 30 x 273  406711409cm3


25  273


The capacity of a tyre 40000cm3 is less than new volume406711409cm3


The tyre thus bursts


3 A hydrogen gas balloon with 80cm3 was released from a research station at room temperature If the temperature of the highest point it rose is 30oC  explain what happened


V1  V2 substituting 80  V2


80 x 30 x 273  652349cm3


The capacity of balloon 80cm3 is more than new volume 652349cm3


The balloon thus remained intact


8 The continuous random motion of gases differ from gas to the otherThe movement of molecules of a gas from region of high concentration to a region of low concentration is called diffusion