JK-TK/Newdata huggingface dataset:
propene molecule can be represented as: H H H H H H H H - C – C - C – C - C – C - C - C - H CH3 H CH3 H CH3 H CH3 Since the molecule is a repetition of one monomer, then the polymer is: H H ( C – C )n H CH3 Examples Polypropene has a molar mass of 4760.Calculate the number of propene molecules in the polymer(C=12.0, H=1.0, ) Number of monomers/repeating units in monomer = Molar mass polymer Molar mass monomer => Molar mass propene (C3H8 )= 44 Molar mass polyethene = 4760 Substituting 4760 = 108.1818 =>108 propene molecules(whole number) 44 The commercial name of polyphenylethene is polystyrene. It is a very light durable plastic. Polystyrene is used: (i)in making packaging material for carrying delicate items like computers, radion,calculators. (ii)ceiling tiles (iii)clothe linings
45 5.Formation of Polytetrafluorothene Polytetrafluorothene is an addition polymer formed when tetrafluoroethene molecule/monomer join together to form a large molecule/polymer at high temperatures and pressure.
It is a very light durable plastic. Polystyrene is used: (i)in making packaging material for carrying delicate items like computers, radion,calculators. (ii)ceiling tiles (iii)clothe linings
45 5.Formation of Polytetrafluorothene Polytetrafluorothene is an addition polymer formed when tetrafluoroethene molecule/monomer join together to form a large molecule/polymer at high temperatures and pressure. During polymerization: (i)many molecules are brought nearer to each other by the high pressure(which reduces the volume occupied by reacting particles) F F F F F F F F C = C + C = C + C = C + C = C + … F F F F F F F F tetrafluoroethene + tetrafluoroethene+ tetrafluoroethene+ tetrafluoroethene + … (ii)the double bond joining the tetrafluoroethene molecule break to free radicals F F F F F F F F •C – C• + •C - C• + •C - C• + •C - C• + … F F F F F F F F (iii)the 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 •C – C - C – C - C – C - C - C• + … F F F F F F F F Lone pair of electrons can be used to join more monomers to form longer polytetrafluoroethene.
Polystyrene is used: (i)in making packaging material for carrying delicate items like computers, radion,calculators. (ii)ceiling tiles (iii)clothe linings
45 5.Formation of Polytetrafluorothene Polytetrafluorothene is an addition polymer formed when tetrafluoroethene molecule/monomer join together to form a large molecule/polymer at high temperatures and pressure. During polymerization: (i)many molecules are brought nearer to each other by the high pressure(which reduces the volume occupied by reacting particles) F F F F F F F F C = C + C = C + C = C + C = C + … F F F F F F F F tetrafluoroethene + tetrafluoroethene+ tetrafluoroethene+ tetrafluoroethene + … (ii)the double bond joining the tetrafluoroethene molecule break to free radicals F F F F F F F F •C – C• + •C - C• + •C - C• + •C - C• + … F F F F F F F F (iii)the 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 •C – C - C – C - C – C - C - C• + … F F F F F F F F 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 molecule/polymer
46 - C – C - C – C - C – C - C – C- + … F F F F F F F F Since the molecule is a repetition of one monomer, then the polymer is: F F ( C – C )n F F Examples Polytetrafluorothene has a molar mass of 4760.Calculate the number of tetrafluoroethene molecules in the polymer(C=12.0, ,F=19 ) Number of monomers/repeating units in monomer = Molar mass polymer Molar mass monomer => Molar mass ethene (C2F4 )= 62.5 Molar mass polyethene = 4760 Substituting 4760 = 77.16 => 77 polychloroethene molecules(whole number) 62.5 The commercial name of polytetrafluorethene(P.T.F.E) is Teflon(P.T.F.E).
(ii)ceiling tiles (iii)clothe linings
45 5.Formation of Polytetrafluorothene Polytetrafluorothene is an addition polymer formed when tetrafluoroethene molecule/monomer join together to form a large molecule/polymer at high temperatures and pressure. During polymerization: (i)many molecules are brought nearer to each other by the high pressure(which reduces the volume occupied by reacting particles) F F F F F F F F C = C + C = C + C = C + C = C + … F F F F F F F F tetrafluoroethene + tetrafluoroethene+ tetrafluoroethene+ tetrafluoroethene + … (ii)the double bond joining the tetrafluoroethene molecule break to free radicals F F F F F F F F •C – C• + •C - C• + •C - C• + •C - C• + … F F F F F F F F (iii)the 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 •C – C - C – C - C – C - C - C• + … F F F F F F F F 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 molecule/polymer
46 - C – C - C – C - C – C - C – C- + … F F F F F F F F Since the molecule is a repetition of one monomer, then the polymer is: F F ( C – C )n F F Examples Polytetrafluorothene has a molar mass of 4760.Calculate the number of tetrafluoroethene molecules in the polymer(C=12.0, ,F=19 ) Number of monomers/repeating units in monomer = Molar mass polymer Molar mass monomer => Molar mass ethene (C2F4 )= 62.5 Molar mass polyethene = 4760 Substituting 4760 = 77.16 => 77 polychloroethene molecules(whole number) 62.5 The commercial name of polytetrafluorethene(P.T.F.E) is Teflon(P.T.F.E). It is a tough, non-transparent and durable plastic.
During polymerization: (i)many molecules are brought nearer to each other by the high pressure(which reduces the volume occupied by reacting particles) F F F F F F F F C = C + C = C + C = C + C = C + … F F F F F F F F tetrafluoroethene + tetrafluoroethene+ tetrafluoroethene+ tetrafluoroethene + … (ii)the double bond joining the tetrafluoroethene molecule break to free radicals F F F F F F F F •C – C• + •C - C• + •C - C• + •C - C• + … F F F F F F F F (iii)the 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 •C – C - C – C - C – C - C - C• + … F F F F F F F F 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 molecule/polymer
46 - C – C - C – C - C – C - C – C- + … F F F F F F F F Since the molecule is a repetition of one monomer, then the polymer is: F F ( C – C )n F F Examples Polytetrafluorothene has a molar mass of 4760.Calculate the number of tetrafluoroethene molecules in the polymer(C=12.0, ,F=19 ) Number of monomers/repeating units in monomer = Molar mass polymer Molar mass monomer => Molar mass ethene (C2F4 )= 62.5 Molar mass polyethene = 4760 Substituting 4760 = 77.16 => 77 polychloroethene molecules(whole number) 62.5 The commercial name of polytetrafluorethene(P.T.F.E) is Teflon(P.T.F.E). It is a tough, non-transparent and durable plastic. PVC is used: (i)in making plastic rope (ii)water pipes (iii)crates and boxes 6.Formation of rubber from Latex Natural rubber is obtained from rubber trees.
polytetrafluoroethene molecule can be represented as: F F F F F F F F extension of molecule/polymer
46 - C – C - C – C - C – C - C – C- + … F F F F F F F F Since the molecule is a repetition of one monomer, then the polymer is: F F ( C – C )n F F Examples Polytetrafluorothene has a molar mass of 4760.Calculate the number of tetrafluoroethene molecules in the polymer(C=12.0, ,F=19 ) Number of monomers/repeating units in monomer = Molar mass polymer Molar mass monomer => Molar mass ethene (C2F4 )= 62.5 Molar mass polyethene = 4760 Substituting 4760 = 77.16 => 77 polychloroethene molecules(whole number) 62.5 The commercial name of polytetrafluorethene(P.T.F.E) is Teflon(P.T.F.E). It is a tough, non-transparent and durable plastic. PVC is used: (i)in making plastic rope (ii)water pipes (iii)crates and boxes 6.Formation 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 2-methylbut-1,3-diene ; H CH3 H H CH2=C (CH3) CH = CH2 H - C = C – C = C - H During natural polymerization to rubber, one double C=C bond break to self add to another molecule.The double bond remaining move to carbon “2” thus;
47 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 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 harder/tougher.
The latex is then added an acid to coagulate the rubber. Natural rubber is a polymer of 2-methylbut-1,3-diene ; H CH3 H H CH2=C (CH3) CH = CH2 H - C = C – C = C - H During natural polymerization to rubber, one double C=C bond break to self add to another molecule.The double bond remaining move to carbon “2” thus;
47 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 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 harder/tougher. During vulcanization the sulphur atoms form a cross link between chains of rubber molecules/polymers. This decreases the number of C=C double bonds in the polymer. H CH3 H H H CH3 H H - C - C - C - C - C - C - C - C - H S H H S H H CH3 S H H CH3 S H - C - C - C - C - C - C - C - C - H H H H H H Vulcanized rubber is used to make tyres, shoes and valves. 7.Formation of synthetic rubber Synthetic rubber is able to resist action of oil,abrasion and organic solvents which rubber cannot. Common synthetic rubber is a polymer of 2-chlorobut-1,3-diene ; H Cl H H Sulphur atoms make cross link between polymers
48 CH2=C (Cl CH = CH2 H - C = C – C = C - H During polymerization to synthetic rubber, one double C=C 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 Generally the structure of rubber is thus; H Cl H H -(- C - C = C - C -)n- H H Rubber is thus strengthened through vulcanization and manufacture of synthetic rubber. (c)Test for the presence of – C = C – double bond.
Common synthetic rubber is a polymer of 2-chlorobut-1,3-diene ; H Cl H H Sulphur atoms make cross link between polymers
48 CH2=C (Cl CH = CH2 H - C = C – C = C - H During polymerization to synthetic rubber, one double C=C 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 Generally the structure of rubber is thus; H Cl H H -(- C - C = C - C -)n- H H Rubber is thus strengthened through vulcanization and manufacture of synthetic rubber. (c)Test for the presence of – C = C – double bond. (i)Burning/combustion 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. Observation Inference Solid melt then burns with a yellow sooty flame – C = C –, – C = C – bond (ii)Oxidation by acidified KMnO4/K2Cr2O7 Bromine water ,Chlorine water and Oxidizing agents acidified KMnO4/K2Cr2O7 change to unique colour in presence of – C = C –
49 or – C = C – bond. Experiment 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 KMnO4/K2Cr2O7 . Observation Inference Acidified KMnO4 decolorized Orange colour of acidified K2Cr2O7 turns green Bromine water is decolorized Chlorine water is decolorized – C = C – – C = C – bond (d)Some 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.
In ripening of fruits. 4. In the manufacture of detergents. (iii) Alkynes (a)Nomenclature/Naming
50 These are hydrocarbons with a general formula CnH2n-2 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: n General/ Molecular formula Structural formula Name 1 Does not exist - 2 C2H2 H C C H CH CH Ethyne 3 C3H4 H H C C C H H CH C CH3 Propyne 4 C4H6 H H H C C C C H H H CH C CH2CH3 Butyne 5 C5H8 H H H H C C C C C H H H H CH C (CH2)2CH3 Pentyne 6 C6H10 H H H H Hexyne
51 H C C C C C C H H H H H CH C (CH2)3CH3 7 C7H12 H H H H H H C C C C C C C H H H H H H H H CH C (CH2)4CH3 Heptyne 8 C8H14 H H H H H H H C C C C C C C C H H H H H H H CH C (CH2)5CH3 Octyne 9 C9H16 H H H H H H H H C C C C C C C C C H H H H H H H H CH C (CH2)6CH3 Nonyne 10 C10H18 H H H H H H H H H C C C C C C C C C C H H H H H H H H H CH C (CH2)7CH3 Decyne 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 bond/one shared pair of electrons. 52 3.
2. Since Hydrogen is monovalent ,each atom of hydrogen in the alkyne MUST always be bonded using one covalent bond/one shared pair of electrons. 52 3. One member of the alkyne ,like alkenes and alkanes, differ from the next/previous by a CH2 group(molar mass of 14 atomic mass units).They thus form a homologous series. e.g Propyne differ from ethyne by (14 a.m.u) one carbon and two Hydrogen atoms from ethyne. 4.A homologous series of alkenes like that of alkanes: (i) differ by a CH2 group from the next /previous consecutively (ii) have similar chemical properties (iii)have similar chemical formula with general formula CnH2n-2 (iv)the physical properties also show steady gradual change 5.The - 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. (b)Isomers 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 IUPAC(International Union of Pure and Applied Chemistry) system of nomenclature/naming. The IUPAC system of nomenclature of naming alkynes uses the following basic rules/guidelines: 1.Identify the longest continuous/straight carbon chain which contains the - C = C- triple bond to get/determine 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 “alk-positions-yne” e.g. but-2-yne, pent-1,3diyne. 4.The position indicated must be for the carbon atom at the lower position in the -C = C- triple bond.
3 Indicate the positions by splitting “alk-positions-yne” e.g. but-2-yne, pent-1,3diyne. 4.The position indicated must be for the carbon atom at the lower position in the -C = C- triple bond. i.e But-2-yne means the triple -C = C- is between Carbon “2”and “3” Pent-1,3-diyne means there are two triple bonds; one between carbon “1” and “2”and another between carbon “3” and “4”
53 5. Determine the position, number and type of branches. Name them as methyl, ethyl, propyl e.tc. according to the number of alkyl carbon chains attached to the alkyne. Name them fluoro-,chloro-,bromo-,iodo- if they are halogens 6.Use prefix di-,tri-,tetra-,penta-,hexa- to show the number of triple - C = C- bonds and branches attached to the alkyne. 7.Position isomers can be formed when the - C = C- triple bond is shifted between carbon atoms e.g. But-2-yne means the double - C = C- is between Carbon “2”and “3” But-1-yne means the double - C = C- is between Carbon “1”and “2” Both But-1-yne and But-2-yne are position isomers of Butyne. 9. Like alkanes and alkynes , an alkyl group can be attached to the alkyne. Chain/branch isomers are thus formed. Butyne and 2-methyl propyne both have the same general formular but different branching chain. (More on powerpoint) (c)Preparation 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. Copper(II)sulphate(VI) is used to catalyze the reaction Chemical equation
54 CaC2(s) + 2 H2O(l) -> Ca(OH) 2 (aq) + C2H2 (g) (d)Properties of alkynes I.
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. Copper(II)sulphate(VI) is used to catalyze the reaction Chemical equation
54 CaC2(s) + 2 H2O(l) -> Ca(OH) 2 (aq) + C2H2 (g) (d)Properties 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 van-der-waals /intermolecular forces as the carbon chain increase. The 1st three straight chain alkynes (ethyne,propyne and but-1yne)are 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 Alkyne General formula Melting point(oC) Boiling point(oC) State at room(298K) temperature and pressure atmosphere (101300Pa) Ethyne CH CH -82 -84 gas Propyne CH3 C CH -103 -23 gas Butyne CH3CH2 CCH -122 8 gas Pent-1-yne CH3(CH2) 2 CCH -119 39 liquid Hex-1-yne CH3(CH2) 3C CH -132 71 liquid II. Chemical properties (a)Burning/combustion Alkynes burn with a yellow/ luminous very sooty/ smoky flame in excess air to form carbon(IV) oxide and water. Alkyne + Air -> carbon(IV) oxide + water (excess air/oxygen) Alkenes burn with a yellow/ luminous verysooty/ smoky flame in limited air to form carbon(II) oxide/carbon and water.
Summary of physical properties of the 1st five alkenes Alkyne General formula Melting point(oC) Boiling point(oC) State at room(298K) temperature and pressure atmosphere (101300Pa) Ethyne CH CH -82 -84 gas Propyne CH3 C CH -103 -23 gas Butyne CH3CH2 CCH -122 8 gas Pent-1-yne CH3(CH2) 2 CCH -119 39 liquid Hex-1-yne CH3(CH2) 3C CH -132 71 liquid II. Chemical properties (a)Burning/combustion Alkynes burn with a yellow/ luminous very sooty/ smoky flame in excess air to form carbon(IV) oxide and water. Alkyne + Air -> carbon(IV) oxide + water (excess air/oxygen) Alkenes burn with a yellow/ luminous verysooty/ smoky flame in limited air to form carbon(II) oxide/carbon and water. 55 Alkyne + Air -> carbon(II) 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 C:H ratio. Examples of burning alkynes 1.(a) Ethyne when ignited burns with a yellow very sooty flame in excess air to form carbon(IV) oxide and water. Ethyne + Air -> carbon(IV) oxide + water (excess air/oxygen) 2C2H2(g) + 5O2(g) -> 4CO2(g) + 2H2O(l/g) (b) Ethyne when ignited burns with a yellow sooty flame in limited air to form a mixture of unburnt carbon and carbon(II) oxide and water. Ethyne + Air -> carbon(II) oxide + water (limited air ) C2H2(g) + O2(g) -> 2CO2(g) + C + 2H2O(l/g) 2.(a) Propyne when ignited burns with a yellow sooty flame in excess air to form carbon(IV) oxide and water.
Examples of burning alkynes 1.(a) Ethyne when ignited burns with a yellow very sooty flame in excess air to form carbon(IV) oxide and water. Ethyne + Air -> carbon(IV) oxide + water (excess air/oxygen) 2C2H2(g) + 5O2(g) -> 4CO2(g) + 2H2O(l/g) (b) Ethyne when ignited burns with a yellow sooty flame in limited air to form a mixture of unburnt carbon and carbon(II) oxide and water. Ethyne + Air -> carbon(II) oxide + water (limited air ) C2H2(g) + O2(g) -> 2CO2(g) + C + 2H2O(l/g) 2.(a) Propyne when ignited burns with a yellow sooty flame in excess air to form carbon(IV) oxide and water. Propyne + Air -> carbon(IV) oxide + water (excess air/oxygen) C3H4(g) + 4O2(g) -> 3CO2(g) + 2H2O(l/g) (a) Propyne when ignited burns with a yellow sooty flame in limited air to form carbon(II) oxide and water. Propene + Air -> carbon(IV) oxide + water (excess air/oxygen) 2C3H4(g) + 5O2(g) -> 6CO(g) + 4H2O(l/g) (b)Addition 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 addition/convert the triple - C = C- to single C- C bond. (i)Hydrogenation Hydrogenation is an addition reaction in which hydrogen in presence of Palladium/Nickel catalyst at 150oC temperatures react with alkynes to form alkenes then alkanes. Examples 1.During 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.
Addition reactions of alkynes are also named from the reagent used to cause the addition/convert the triple - C = C- to single C- C bond. (i)Hydrogenation Hydrogenation is an addition reaction in which hydrogen in presence of Palladium/Nickel catalyst at 150oC temperatures react with alkynes to form alkenes then alkanes. Examples 1.During 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
56 HC = CH + H2 -Ni/Pa -> H2C = CH2 + H2 -Ni/Pa -> H2C - CH2 H H H H H H C = C + H – H - Ni/Pa -> H - C = C – H + H – H - Ni/Pa -> H - C - C – H H H H H H H 2.Propyne undergo hydrogenation to form Propane Chemical equation H3C CH = CH2 + 2H2 -Ni/Pa-> H3C CH - CH3 H H H H H H H C C = C + 2H – H - Ni/Pa-> H - C – C - C- H H H H H H 3(a) But-1-yne undergo hydrogenation to form Butane Chemical equation But-1-yne + Hydrogen –Ni/Pa-> Butane H3C CH2 C = CH + 2H2 -Ni/Pa-> H3C CH2CH - CH3 H H H H H H H H C C - C = C + 2H – H - Ni/Pa-> H - C- C – C - C- H H H H H H H (b) But-2-yne undergo hydrogenation to form Butane Chemical equation But-2-yne + Hydrogen –Ni/Pa-> Butane H3C C = C CH2 + 2H2 -Ni/Pa-> H3C CH2CH - CH3 H H H H H H H C C = C - C H + 2H – H- Ni/Pa-> H - C- C – C - C- H H H H H H H
57 (ii) Halogenation.