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Dubai

Grade 12 Organic Chemistry

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Published in: Chemistry
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Organic Chemistry Notes along with Worksheets and Answers

Nathan P / Al Ain

15 years of teaching experience

Qualification: Higher Diploma in Education. High School. Majoring in Physics, Mathematics and Chemistry.

Teaches: Maths, IGCSE/AS/AL, Chemistry, Physics

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  1. 1 1. 1. 1.3 1. 1.5 1. c=c—c—c 12 KA : MATTER & M : Term 1 ORGANIC MOLECULES Worksheets SOLUTIONS 4.3 CH3 C H 2 CH 4.4 8 18 5. 5.1 C H n 2n+2 1 .1 2 4 6 carbon or organic When carbon atoms bond covalently to other carbon atoms in short or long chains or rings man-made millions Hydrocarbons are molecules consisting of carbon and hydrogen atoms only. alkanes CH CH 3 5.2 Compounds in which there are no multiple bonds between C atoms in their hydrocarbon chain. ( It contains only single bonds between carbon atoms and the carbon atoms are surrounded by the maximum number of hydrogen atoms.) 8. 8.1 Hydrocarbons with double bonds. 8.2.1 H H H 8.2.2 H H H H H H 2. 2.1 2.2 H H H H 5.3 5.5 6. 6.1 unreactive little 5.4 5.6 well are A series of organic compounds that can be described by the same general formula OR in which one member differs from the next with a CH2 group. 8.3 Organic molecules with the same molecu- lar formulae, but different structural formulae. 8.4 Yes. They have different boiling points. 8.5 C H 8.6 Compounds with one or more multiple bonds between C atoms in their hydrocarbon chains. (The carbon atoms have multiple bonds be- tween them and thus they are not surrounded by the maximum number of hydrogen atoms.) 2.3 3. 3.1 3.2 CH or CH 3.3 4. 4.1 4.2 6.2 6.5 6.6 6.7 7. 7.1 7.2.1 yes 6.3 yes 6.4 C H n 2n+2 yes Physical properties change slightly and regularly as the chain length gets longer. Boiling points increase. straight chain or branched chain 9. 9.1 9.2 9.3 9.4 10. 10.1 10.2 10.3 Alkynes are hydrocarbons with a triple H H H H H H H H H H H bond. ethyne / acetylene unsaturated the hydroxyl group CH2 CH2 CH 3 ( CH3 4 10 -OH 7.2.2 ( better ) The double bond must alternate with a single bond. The next two examples are not conjugated double bonds. 7.3 delocalised 7.4 Delocalised electrons are free to move around the whole molecule, making the molecule more stable as the delocalised electrons can move further away from each other, as they can occupy the whole molecule , and thus repel each other less. Delocalised electrons do not belong to one atom, they belong to all the atoms in the molecule. 10.4 CH CH20H 10.5 A functional group is a bond or an atom or a group of atoms that determine(s) the physical and chemical properties of a group of organic compounds. 10.6 They all have the same functional group which is what determines their chemical behaviour. normal or unbranched or straight -chain alkanes. 10.7 CHO 6 12 6 2 c H OH +2 co 2 H H H H H H Fermentation of sugar 10.8 co 2 10.9 It is a greenhouse gas that increases global warming and climate change. 10.10 Fermenting crops to make ethanol produces CO The fertilizers used to grow the biofuel also produce greenhouse gases. Edible crops that are used for biofuel mean that less food will be available for people to eat.
  2. 12 КА : MATTER М : Тет 1 ORGANlC MOLECULES Worksheets SOLUTlONS 11. 11.1 11.2 11.3 13.4 ВГ 14. 16.1 се Н н-с—с—с—с Н Н Н Н Н Н Н Н Н antifreeze 14.1 Asubstituent is а side chain or atom that is stuck onto а carbon chain, that is longer than the substituent, and gives rise to а branched chain if the substituent has опе or тоге carbon atoms. Н Н propan-1-0' сз ОН propan-2-ol сзн он н- о—с—с—с н- н—с—с—с н—с—с—с Вт -С —С— С —С —С О Н Н О 14.2.1 н сн 14.2.3 14.2.2 н н н-с—с—с О Н снз- 12. 12.1 .1 12,1.2 12.2.1 12.2.2 12.2.3 12.3 13. 13.1 13.2 13.3 Н Н Н Н Н Н снзснг 14.2.4 15.1 н—с—с—с— Н Н - он R represents апу alkyl group сн - н Н Н от сн - Н Н СЕ Н н-с—с—с—с н Н о Н О Н се Н Н н Н се Н Н Н се etc. Н 15.2. Н Н н—с—с—с н н н—с—с—с н 16.2.1 Н 16.2.2 17. 17.1 17.2 н—с—с н- Н or н О се Н се pentane methylbutane dimethylpropane се
  3. 12 KA : MATTER & M : Term 1 ORGANIC MOLECULES Worksheets SOLUTIONS 17.3 17.4 17.5 18.1. 18.3 18.4 18.5 18.6 18.7 18.8 18.9 18.10 18.11 18.12 18.13 18.14 18.15 18.16 18.17 18.18 18.19 19.1 19.2 19.3 19.4 C H OH n 2n+1 20.8 20.9 O O H H H—C—C—C H H H H H 18.2 H H H H hexane A functional group is a bond or an atom or a group of atoms that determine(s) the physical and chemical properties of a group of organic compounds. 19.5 They can be represented by a general formula. Successive members differ by — CH There is a slight regular change in their physical properties as we move from member to member. All members have similar chemical behaviour due to having the same functional group. 19.6 LPG ( liquid petroleum gas ) benzine, petrol, paraffin, diesel, lubricating oils, paraffin wax, bitumen. 19.7 Fossil fuels : coal, oil, natural gas. 19.8 Fuels 19.9 Make plastics and paints. 19.10 Oxy-acetylene welding and metal butane but-I-ene propan-2-ol but-2-yne butanoic acid ethanoic acid propan-l-ol cutting. 19.11 Acetylene 2,4-dimethylpentane 2-methylbutane dichloromethane tetrachloromethane 1 ,2-d ich loro-l -fluoro-l -iodoethane bromotrifluoromethane 1 ,2-dichloroethene 1 ,3-dibromo-1 ,3-dichloropropane 2, 3-dibromopropene methylpropane 1 -bromo-l ,2-dichloro-1 -iodoethane 18.20 I-chloro-2,3-difluorobut-1-ene ( always number from the end closest to the double bond ) 20. 20.1 20.2 20.3 20.4 20.5 20.6 20.7 20.10 20.11 20.12 20.13 20.14 20.15 20.16 I—c— 20.17 H-C H-C H H—C—C—C H H-C—C—C—C H H H H H H H H H O H-C O H H- H- H- O H H H-C—C H-C=C H-C—C=C— H-CEC O H H H- H- H cc H- —c —c —cc
  4. 12 КА : MATTER М : Тет 1 ORGANlC MOLECULES Worksheets SOLUTlONS 20.18 -о—с 20.19 се н- н—с—с—с н—с н—с—с— н—с 23. 23.1 сн сн он +0 24.5 сн соон + н о н—с—с —с 23.2 23.3 carboxyl group hydroxyl group 20.20 20.22 20.23 21.1 21.2 22. 22.1 се —с —се се н- се 20.21 се —с—се 23.4.2 с Н 23.4.3 23.4.4 24. 24.1 24.2 Н н—с—с—с—с н Н н—с—с н—с Н —о Н О —с О —о -о 25. 25.1 Alcohol 25.2 Catalyst and dehydrating agent. 25.3 Parts of molecules. 25.4 slow 25.5 alcohol 25.6 is 25.7 product 25.8 ester + water 26. 26.1 methyl methanoate 26.2 methyl ethanoate 26.3 methyl propanoate 27. 27.1 н-с- 27.2 27 .з С - 07 о О —о— Н Н С 1 , 1 -dichloroethane butane СНЕ 1 сн сн 1-fluoro-1 -iodopropane 22.2 CHBrF СН CHBrCH 1 ,3-dibromo-1-fluorobutane 22.3 СНЗ (CHCt)2 СН2 ОН 2,3-dichlorobutan-1-ol 22.4 СНЕ- I (CHF)2 снсе СН2СН н О о—с—с о Н —о— Н 4-chloro-1 22.5 снзсн(снз) снсе 24.3 1-bromo-3-ch loro-2,4-d imethylpentan-1 -о' 22.6 снен сн(снз) снен 24.4 2-methylpropan-1 ,3-diol 27.4 27.4.1 о с—с н
  5. 12 KA : MATTER & M: Term 1 ORGANIC MOLECULES Worksheets SOLUTIONS 27.4.2 —c —o—c 28. 28.1 H-C-C— H- 28.2 31.2 28.3 O—c —o—c— o c H 30.2 Proton transfer CH COOH 30.3 31.1 CH COONH c H ammonium ethanoate H—C—O—C—C- methyl ethanoate water cc-c=c H —c—c 2-methylbut-l-ene I-chloropropyne butanoic acid ethyl ethanoate H O O o—c—c H O O H 28.4 H—C 29. 29.1 CH COOH —o—c O also also methyl propanoate propyl methanoate H H—C O 31 C 32. 32.1 —0— c=c propanoic acid propane-I ,2,3-triol ethanoic acid methyl methanoate H 2 SO 29.2 29.2 CH COO- OH - CH COOH + NaOH 29.3 30. 30.1 CH COO- Ethanoate ion CH COONa sodium ethanoate methyl ethanoate Hydrated proton or oxonium ion or hydronium ion water water 32.2 A series of organic compounds where the members differ from each other with the same group of atoms — CH2 and all the members are described by a general formula and have the same functional group. 32.3 Aliphatic means " straight line ' C H OH n 2n +1 32.4 ethyl methanoate H—C—C—O—C—H 33. 33.1 -c-o-c- H H 33.2 Proton transfer CH COOH + H ethanoate ion + hydrated proton H —C—C—C—C ethyl pentanoate
  6. 12 KA : MATTER & M: Term 1 ORGANIC MOLECULES Worksheets SOLUTIONS 6 propyl methanoate Ketones are formed by the carbonyl group 35.2.1 propanone 35.2.5 butandioic acid 35.2.8.1 o 36. 36.1 37. 37.1 37.4 38.1 39. 39.1 39.2 40.1 41. 41.1 41 .3 H H 41.5 42. 34. 35. 35.1 —c—c—c—c o—c—c—c H-C H-C H-C-C- c=c H-C 41 .6 cc -c—c- cc H H H H O H H—C— O H c butanal hexanal O I-I-C-H prop-2-yl methanoate H molecular formula for all three: C H O C = O attached to two alkyl groups. butanoic acid 35.2.2 35.2.6 butanone hexanoic acid 35.2.3 35.2.7 35.2.8.2 36.2.1 36.2.3 pentan-3-one octanoic acid 35.2.4 hexan-2-one H H H H O H 37.2 37.5 H The carbonyl group and an H H O -C-H propanal pentanal 36.2.2 36.2.4 propan-l ,2,3-triol butan-2-ol pentanoic acid hexanal O H H H H H H 37.3 octandioic acid 38.2 o—c—c—c—c 1 ,2,3-tribromocyclohex-1-ene I-bromo-2-methylcyclopentane count clockwise in order to obtain smaller numbers 39.3 1, I-dichlorocyclopropane butan-2-ol 40.2.1 methylbutane , pentane methylbutane , dimethylpropane H H H H H H H H-C H H H H-C-C- H H 42.2 alkynes 42.3 H H H H 40.2.2 41 .2 41 .4 H H H H H H H H H H no reaction. H H H —C-Br H 42.1 alkenes alkenes, if two alkyne bonds have to break as in complete combustion. If only one alkyne bond has to break, then the alkyne reacts faster as this third bond is very weak. 42.4 smoky ; yellow 42.9 hydrogenation 43.4 is 42.5 clear ; blue 42.6 43. 43.1 44. 44.1 vegetable oil ethyne 42.7 43.2 nickel calcium carbide 42.8 43.3 C2H2 42.10 43.5 many is 42.11 43.6 soft is H H 44.2 H-C=
  7. 12 KA : MATTER & M: H H H F Term 1 ORGANIC MOLECULES Worksheets SOLUTIONS 7 44.3 H 44.4 c=c 44.5 44.6 H—C— H—C c- c=c -c=c H-C— H—C—C 1 H H H F H cc H 47.2 47.2.1 47.2.2 47.2.3 47.2.4 47.3.1 carboxylic acid ester methanoic acid methyl methanoate ( the " R " represents any alkyl group ) alkyne haloalkane ethyne bromomethane H- H- H H H H H H H H H Ca (OH) 2 47.3.2 H H—C— H 47.4 474.1 47.4.2 H H H H H H 45. 45.1 Cac 45.2.1 2 H 20 C 2 conc H SO 4 C 2 H 2 H 4 A good solvent for oil, non flammable, volatile (it dries quickly ). CH + 2,50 —>2C0 + HO OH 45.2.2 45.3.1 45.3.2 45.3.3 45.3.4 45.4.1 H H 45.4.2 dehydration propdiene buttriene butdiyne hextriyne H H-C-C-O H Vinegar 51, H 2,3 H H O sulfuric O The reaction is very exothermic, liberating much thermal energy 47.5 The pi component of the double bond is weaker than the sigma single bond. Less energy is required to break it. It snaps more easily and thus ethene is more reactive. —c-c c- H H H Addition CH CH2cc C2H50H or C2H2 C2H5COOCH 3 hydronium ion ammonium ion ion 48.3 1-14 2-chlorobutane ( it was the staple drink of the Roman army ). 49.2 49.4 49.6 HCOOH C2H50H 46. 46.1.1 alkenes 46.2.1 alkanes 46.3.1 46.3.2 46.4.1 46.4.2 46.5.1 do 47. 47.1 .1 47.1 .2 46.1.2 46.2.2 unsaturated saturated propan-l ,2,3-triol H H alkynes alkanes H O H—C—C H O H O H 46.5.2 46.1.3 46.2.3 46.4.3 46.5.3 H O H H H H No reaction. H—C—c- H H + K—OH more H ethanol O alkynes alkenes is add + K—Br H potassium bromide 48. 48.1 48.2 49. 49.1 49.3 49.5 49.7 49.8 50. 50.1 50.2 51. 51.1 51 .2 51 .3 51 .4 52. 52.1 52.2 52.3 52.4 Dilute sulfuric acid or phosphoric acid. 3300C and 60 atmospheres. The catalyst is recovered unchanged at the end of the reaction. CH + 502 3 co C3 H 6 + 02 3 CO CH OH + 1,50 The haloalkane is hydrolysed to an alcohol. 2 1-120 5 H 20
  8. 12 KA : MATTER & M: Term 1 ORGANIC MOLECULES Worksheets SOLUTIONS 8 53. 53.1 H 53.2 53.3 54. 54.1 54.2 54.3 54.4 54.5 61 .3 55. 55.1 H 55.2 56. 56.1 H 56.2 56.3 56.4 56.5 57. 57.1 H 57.2 57.3 57.4 58. 58.1 H -c 58.2 58.3 58.4 59. 59.1 H 59.2 C substitution the presence of light or heat C = C—H + C-H hydrohalogenation must not the - OH is added instead of the Markovnikov H H H H H H H -c H -c O elimination thermal or catalytic cracking high pressures and temperatures with no catalyst lower temperatures and pressures H -c H H c 60. 60.1 H 60.2 60.3 60.4 60.5 .1 H 61. 2 61 .4 62 .1 H 62.2 62.3 63. 63.1 H 63.2 H O C -C-H H O hydration must concentrated sulfuric acid H c H H C H addition H H H H hydrogenation it must be dissolved in a non-polar solvent H C H H H H c H C H hydrohalogenation must not the - OH is added instead of the The H atom is added to the C atom which already is H c H H c H H -C - Br+ NaOH H bonded to most of the H atoms H 2 SO 4 H H c H H C H H C- OH + NaBr H H c H O HX H H c H O C H Ethanol. hydration water small amounts of acids ( halogen acid ) or other strong Electronegativity difference between Br ( 2,8 ) and c (2,5) is 0,3. The C- Br bond is < and is non-polar and thus I-bromopropane is insoluble in polar water and won't mix with ionic NaOH. Dissolve it in ethanol and then it mixes with the NaOH (aq). H C H H H H H hydrogenation 63.3 64. 64 .1 Yes, warm the mixture to increase the reaction rate. a non-polar solvent , to increase the concentration as ethene is a gas platinum, palladium, nickel H H H H H H O H c C-H H c H H c H H H C -O + I-I-Br H c halogenation 64.2 Yes. Water splits into H- and added to two separate molecules. 64.3 very slow -OH which are
  9. 12 KA : MATTER & M: Term 1 ORGANIC MOLECULES Worksheets SOLUTIONS 9 65. 65.1 H-C-C=C -H + NaBr 65.2 65.3 65.4 65.5 65.6 65.7 65.8 H-C-C=C -c -c H H H c H H H O C K2Cr207 + NaOH H c C H H H c H H H H dehydrohalogenation hot, concentrated The NaOH is less soluble in ethanol which prevents the - OH doing a substitution reaction with the Br O carboxylic acid oxidising agent oxidation reaction no H c H O C H H O O A concentrated solution of NaOH or KOH in pure ethanol as solvent. C- Br is a non-polar bond, it won't mix with ionic NaOH. KOH Vapours condense in a fractionating column and return to the The reaction is thermally accelerated by being at a high temperature, the solvent's boiling point. This temperature remains constant. The reaction flask will not boil dry for a long time as the vapours re-condense and flow back into the flask. O c H H c H H H K2Cr207 H H 66. 66.1 66.2 66.3 67. 67.1 67.2 67.3 67.4 67.5 68. 68.1 H 68.2 68.3 68.4 69. 69.1 H 69.2 69.3 69.4 69.5 69.6 but-2-ene H H H H H H H ketone secondary alcohol oxidising agent oxidation reaction no HSO - H H H c H H c H H H H H + NaOH _ H + NaOH C H + NaBr but-I-ene —H O 70. 70.1 H 70.2 70.3 70.4 70 .5 71. 71. I H 71. 2 71.3 71. 4 71.5 71. 6 72. 72.1 Note : H SO + H SO 4 HSO 4 4 NaBr HSO SO HBr O NaHSO 4 100 % ionisation 1 % ionisation H H H c H H C H —H The second step of ionization hardly occurs. + NaBr 72.2 substitution CH CH CH OH + HBr 72.3 CH3CHOHCH + HBr CH CH CH2Br + HO CH CHBrCH but-2-ene Zaitsev. Remove the H from the C O that has fewest H atoms H H H H O H 2 SO 4 H 72.4 73. 73.1 73.2 73.3 secondary haloalkane HBr done at room temperature CH 3 H H dehydration concentrated sulfuric or phosphoric acid yes It acts as a dehydrating agent and as a catalyst. O O O H CCH CH COH + HBr CH 3 H CCH CH CH 3 CBr CH 3 73.4 73.5 73.6 74. 74.1 74.2 74.3 2-bromo-2-methylpentane and substitution reaction water Yes. The acid must be concentrated. H c H H C H H O AC203 H c H H H H H H H elimination / dehydration acts as a catalyst vapour or gas H O C H—C—C —C—H H -c H H H An unsaturated hydrocarbon is more reactive as the second bond in a double bond is weak and snaps easily. O K2Cr207 H 75. 75.1 75.2 2 1-120 + Ca (OH) 2 aldehyde primary oxidising agent oxidation reaction yes
  10. 12 KA : MATTER & M: Term 1 76. 76.1 The bromine loses its brown colour rapidly. ORGANIC MOLECULES Worksheets SOLUTIONS 82.4 Always attractive, very weak, not directed in a specific 10 76.2 H H H H H -c H 76.3 Addition reaction. 76.4 The molecules can lie parallel to each other with bigger surface areas in contact. This causes stronger Van der Waals forces between the molecules which need a higher temperature to break them. 77. 77.1 c 77.2 77.5 CH3CH20H ethanol 78. B 77.3 E 77.4 A, + HI CH CH21 + H O iodoethane 78.1 Organic chemistry has more bonds to be broken and more bonds to be formed. We work with atoms and parts of molecules. There are no ionic charges to assist in forming bonds. 78.2 No. Alkenes have double bonds and thus are not satu- rated. 78.3 Ethyne has a triple bond which breaks more easily than the single bonds of ethane. 78.4 78.5 So 78.6 79. 79.1 CH +302 —>2C0 +2 HO 28 g 96 g 2,8g needs 9,6g dioxygen. CH OH + methanol HCOOH methanoic acid HCOOCH + H O methyl methanoate M (C2 1-16) = 24 + 6 ethane 79.2 In a homologous series successive member. - 30 g•moe -1 — CH2 must be added to get each 79.3 Larger molecules have a larger mass with more electrons ( a greater electron density ) and larger surface areas in contact, and thus have stronger Van der Waals forces between molecules Thus they have a higher boiling point. - 58 g•moe -1 79.4 M (C 4 HIO) — 48 + 1 0 Butane has a freezing point of about OOC. Europe gets sub zero in winter. Thus use propane as it freezes at — 500C. 80. 80.1 80.2 80.3 80.4 80.5 81. 81.1 81.2 81.3 81.5 81.7 81.8 82. 82.1 82.2 82.3. A dipole is a molecule with a positive and a negative pole. A dipole can induce a temporary dipole in a neutral molecule. Van der Waals forces Van der Waals forces vaporisation of a solid from solid to vapour. Iodine and solid carbon dioxide (dry ice ) Van der Waals forces Van der Waals forces hydrogen hydrogen Van der Waals forces Van der Waals forces 88.4 88.6 hydrogen hydrogen Water has strong hydrogen bonds between molecules. H Te has weak Van der Waals forces. higher 30 62 direction, they have temporary, fluctuating dipole moments that are changing position as they flicker. 82.5 Usually soft, low melting points, non-conductors, can sublime from solid to vapour. 82.6 Both are due to electrostatic forces and both are between molecules. Hydrogen bonds are stronger and are directional. 82.7 Longer chain molecules form stronger Van der Waals forces. The Van der Waals forces depend on the number of electrons surrounding the molecule and the space that they can move in. This depends on the molecular mass. Molecules with a larger molecular mass also have larger surface areas in contact. Thus molecules with a larger mass have higher boiling points in order to have enough energy to break the stronger bonds. 82.8 Water has strong hydrogen bonds between its molecules. H S has weak Van der Waals forces. 83. 83.1 London forces are forces of attraction between fluctuating dipoles in atoms and molecules that are close together. 83.2 London dispersion forces are forces of attraction between fluctuating dipoles in atoms and molecules that are close together. Can be called weak Van der Waals forces. 83.3 Water, ammonia, hydrogen fluoride. 83.4 N, O and F have highly electronegative atoms that are able to rip the electron off a hydrogen atom, leaving it as a tiny proton and creating a dipole as a F - ion forms. The tiny proton can get very close to another F - ion and form a strong hydrogen bond. 83.5 They are stronger than Van der Waals forces and they are directional. 83.6 Being strong they cause water to evaporate slowly, else our seas, lakes and dams would dry up as they evaporate away. Hydrogen bonds link the double helix in DNA and thus they hold living things together. Hydrogen bonds allow ice to form with an expanded less dense structure that floats on water. This acts as an insulating surface layer which prevents the rest of the water from freezing. Under this frozen surface fish and marine life survive and the deep sea currents are able to continue flowing. 83.7 Oxygen has a high electronegativity to strip hydrogen of its electron. A strong dipole forms. The hydrogen bond is due to strong dipole - dipole attractions. Sulfur has too little electronegativity. 84. 84.1 Ice floats on water. Directional hydrogen bonds form ice with an expanded less dense structure that floats on water. 84.2 As they are strong they cause water to evaporate slowly else our seas, lakes and dams would dry up as they evaporate away. Hydrogen bonds link the double helix in DNA and thus they hold living things together. Hydrogen bonds allow ice to form with a strong, expanded less dense structure that floats on water. This acts as an insulating surface layer which prevents the rest of the water from freezing. Under this frozen surface fish and marine life survive and the deep sea currents are able to continue flowing.
  11. 12 KA : MATTER & M : Term 1 ORGANIC MOLECULES Worksheets SOLUTIONS 11 84.3 Hydrogen bonds allow ice to form with a strong, expanded less dense structure that floats on water. This acts as an insulating surface layer which prevents the rest of the water from freezing. Under this frozen surface fish and marine life survive and the deep sea currents are able to continue flowing and is a good conductor. CH3CH2CH2CH2- O -c- 3 polar 84.4 84.4.1 84.4.2 84.4.3 84.5 84.5.1 84.5.2 84.5.3 84.5.4 84.5.5 84.5.6 84.6 84.6.1 84.6.3 84.6.4 84.6.5 Hydrogen bonds between molecules, covalent bonds between atoms in the molecules. Van der Waals forces between molecules, covalent. bonds between atoms inside the molecules. Hydrogen bonds at the polar ends and Van der Waals forces at the non-polar ends. Raise the BP ( boiling point ) as more thermal energy is needed to break the bonds. Slow down the rate of evaporation as stronger forces hold the molecules together. Decrease the volatility as fewer gas molecules can escape Reduce the vapour pressure as fewer gas molecules form Increase the viscosity ( liquid becomes less runny) as stronger forces hold the molecules together. Increase the runniness ( viscosity ) of the liquid as stronger forces hold the molecules together. The non-polar oily alkyl portion is now long enough to cancel out the solubility of the polar carbonyl group. 85.2 85.2.1 The hydroxyl group (— OH ) is polar and competes with the oily non-polar alkyl group. As long as this alkyl tail is short, the nature of the molecule is dominated by solubility of the —OH. 85.2.2 The non-polar oily alkyl portion is now long enough to cancel out the solubility of the polar hydroxyl group, —OH. 85.2.3 2-methylpropan-2-ol Infinitely water-soluble. CH3- CH 3 3 OH It is the hydrogen bonds that make them water -soluble. The more compact spherical molecule breaks fewer hydrogen bonds that exist between water molecules when it fits into the water. These are easily replaced by the OH group forming new hydrogen bonds with the water molecules. 2-methylpropan-l-ol 11% water-soluble. CH 3 CH3-CH- CH2-OH weak 91.6.2 quickly high (as there are a lot of gas particles ) low ( as the weak intermolecular forces snap easily so that lots of gas particles can form ) The molecules can lie parallel to each other with bigger surface areas in contact. This causes stronger Van der Waals forces between the molecules which need a higher temperature to break them. But the shape of the hydrocarbon portion is important. Side chains make the molecule more compact and thus they require less room and break fewer water hydrogen bonds in their aqueous solutions, making them more soluble. This molecule is less spherical and has a bigger volume. Thus it breaks more hydrogen bonds between the water molecules when it fits into the water. The OH group cannot form this many hydrogen bonds with the water molecules and is thus not very soluble in the water. 85.3 The three OH groups can form hydrogen bonds with water molecules. 85.4 Adding a non-volatile liquid ( that does not easily evaporate ) raises the boiling point and lowers the freezing point of water. Ethan-I ,2-diol has two OH groups which can form hydrogen bonds with water ( making it water-soluble ) and these strong hydrogen bonds stop it from evaporating easily so it is also non- 84.7 84.7.1 84.7.2 84.7.3 84.7.4 84.7.5 Water. It has the highest BP and thus the strongest intermolecular forces ( which are hydrogen bonds ) Acetone. It has the lowest boiling point which means it has the weakest intermolecular forces. Acetone. It has the lowest boiling point which means it has the weakest intermolecular forces and thus has the most gas particles to produce the vapour pressure. Acetone. Acetone. It draws thermal energy from your skin so that volatile. 85.5 85.5.1 caC2 (s) + 2 1-120 (C) 1-12 (g) + 85.5.2 alkane Ca (OH)2 (aq) the liquid particles can evaporate. Weak intermolecular forces means rapid evaporation which we experience as a very cold 86. 86.1 86.2 86.4 86.6 86.8 86.10 87. 87.1 87.3 87.5 88. 88.1 88.2 88.3 88.4 88.5 88.6 88.7 88.8 88.9 88.10 88.11 lower; compact; gases increases increases increases non-polar; weak polar; stronger ; higher increases are not mix stronger higher weaker ( smaller surface area in contact ) feeling. This numbs our nerves. 84.8 84.8.1 strong 84.8.2 will 84.8.4 alcohols and ketones 84.8.3 alcohols and ketones 86.3 86.5 86.7 86.9 86.11 87.2 87.4 solids increases increases non-polar ; non-polar ; more increases weak weak 85. 85.1 CH3CH COCH 3 CH CH2- O -c- non-polar polar Get the electronegativities from the periodic table. AE 03'5 -C25 AE C2,5 _ H2 1 CH CH COCH CH -CH CH -CH 3 3 CH CH2- O carbonyl group -c- non-polar polar As the non-polar portions get longer, the molecule gets more oily and starts cancelling out the solubility of the polar carbonyl group. strong hydrogen bond be miscible weak Van der Waals forces not mix ethanol increases are combustible ( so they can be used as fuels )
  12. ORGANIC MOLECULES Worksheets SOLUTIONS 89. 89.1 89.3 90.1 91.3 91.5 12 KA : MATTER & M: Term 1 are not less 12 89.2 do not mix Chemical behaviour depends on the valence electron configuration 90.2 If an unpaired electron is attached to an atom it forms a free radical. 90.3 It is very reactive as its unpaired electron seeks another electron to form a pair with. 90.4 A free radical can break the pi component of a double bond and then pair off with one of the electrons. 94. 94.4 Many of the chemicals are corrosive, flammable and toxic. The gases can escape into the air. Hot liquids can spill. Fires and explosions can occur. 94.5 People must wear protective clothing, helmets, gloves, goggles. They must be trained to cope with these dangers. They must be trained to use the correct safety equipment. 94.6 94.7 94.8 94.9 •CH 94.10 CH• + CH. 90.5 H H H H 3 + CH CH 3 + CH 3 CH + •CH CH ignore lone pairs -CH 3 CH 3 3 2 91. 91. 91. 91. 1 2 4 SASOL, South Africa Crude oil is a mixture of carbon chains of different lengths. bitumen, fuel oil, wax, diesel fuel, paraffin, petrol, heavy naphtha, light naphtha, liquid petroleum gas, natural gas ( methane ) fractionating column As temperature rises, so the molecules move faster until •CH CH + 2 they move so fast that some of the bonds between C atoms are able to break. 95. 95.1 95.2 95.3 95.4 Mozambique Yes. H and CO react under pressure at a moderate temperature us- 91.6.1 91.7.1 91.7.2 91.8.1 91.8.2 7-12 C atoms 99.6.2 5-7 C atoms petrol or gasoline and petrochemicals ethene and petrochemicals 750C to 200C to 750C 92. 92.1 92.2 92.3 92.4 92.5 93. 93.1 Pyrolysis is the breaking up of a molecule when heated. Thermal cracking or catalytic cracking. Zeolites which are composed mainly of silica and alumina. 3 CH3CH • 2 CH CH2CH • 2 CH CH 3 CH CH2CH CH • 2 CH• + . 3 CH• + CH CFI • 2 CH CH• + CH CH • 2 CH• + CH CH CFI • 2 CH CH CH 3 CH CH2CH CH 3 CH CH CH CH 3 In a free radical, a H atom is transferred to another free radical, away from the C atom that is next to the C atom that has the free radical electron. Thus a double bond can form between these two 93.2 An alkane and an alkene. ing an iron based catalyst. This produces a broad spectrum of hydrocar- bons usually in the Cl to C20 range. 95.5 a broad spectrum of hydrocarbons usually in the Cl to C20 range. The syngas is converted into petrol and other fuels. 95.6 CH4 is what we started with. It is a primary feedstock of the syngas. So we have simply made what we started with. 95.7 longer 95.8 It simply gets too expensive. Big compressors, high quality welding and thick metal pipes are needed. 95.9 The cracking process also increases with higher temperatures, producing more unwanted methane CH 95.10 Iron or cobalt. 95.11 Under compression, longer molecules tend to self ignite before the spark ignites them. This causes a knocking sound in the engine. Branched chains are shorter and more compact and cope with the pressure without pre-detonation. 93.3 CH CH • CH CH • CH CH2CH • 2 CH CH2CH • 2 CH CH3 CH C atoms. CH CH=CH CH 2 3 94. 94.1 94.2 94.3 ethene A high temperature is required to break the strong covalent C —C bonds. The acidic cooled gases are neutralised by passing them through a base.
  13. 12 KA : MATTER & M : Term 1 ORGANIC MOLECULES Worksheets SOLUTIONS 13 96.1 96.2 96.3 o-c c=c —o-c-c -c-c-c-c-c-c c=c c=c H H H H H H H H H H H H H -c-c-c-c-c-c H or H H Polythene polyethelene. 96.4 polyethene or 98.1 Make squeeze bottles, plastic bags for supermarkets, films, toys, moulded objects, electric insulation. 98.2 4 98.3 Polythene 98.4 Mylar 98.5 Kevlar 98.6 Lexan, a polycarbonate. 98.7 They are non-biodegradable and thus cause unsightly litter and they clutter up city land-fill rubbish dumps. 98.8 The plastic parts are lighter than metal parts and a lighter car uses less fuel which produces less greenhouse gas CO that causes global warming and climate change. 98.9 In a collision the plastic crumples which absorbs most of the impact. The bumper is easily detached from the car and this destroys the bumper but removes a lot of the collision energy which saves the car from damage. Replacing a bumper is cheaper than panel 101.2 monomer is styrene or phenylethene 101.3 polystyrene 101.4 Polystyrene is light and rigid and is used for packaging, picnic utensils like disposable cups, insulation in buildings, cooler boxes etc. 101.5 6 102.1 Macromolecules are are molecules that consist of a large number of atoms. 102.2 A functional group is a bond or an atom or a group of atoms that determine(s) the physical and chemical properties of a group of organic compounds. 102.3 Free radicals are very reactive atoms or H H H H n molecules which have unpaired electrons. 103.1 CH 3 O H O O 96.5 Avery big number. 96.6 Remove the n and the square bracket and use the two unattached horizontal bonds to reform the original double bond. beating the car and its chassis. 99.1 F F F F 99.2 F F F F polymer CH H H H 97.1 H H c=c H H H H H H cc 3 C O repeat unit n n cc H H 3 O 3 O H H H cc n 99.3 F F F F tetrafluoroethene 103.2 CH 3 o-c H CH o-c 103.3 103.4 103.5 103.6 H O CH 3 H CH H O 97.2 97.3 97.4 H H H H H monomer 99.4 Teflon 99.5 addition polytetrafluoroethene PTFE step-growth polymerization water CH 3 Polytvinyl chloride H H H cc 99.6 Its surface is smoothest and needs no lubrication. So it makes low friction slid- ers that are fitted under objects if they are to be moved around. Non-stick pans are coated with teflon. Makes a stain repellent for carpets and clothes as it does not react with anything. 97.5.1 Vinyl means an ethene molecule has lost a hydrogen atom. 100.1 H H H 97.5.2 97.5.3 OCCH 3 O H OCCH 3 O vinyl functional group vinyl chloride repeat unit 100.2 vinyl acetate monomer cc Vinyl chloride means that a chlorine atom has replaced the hydrogen atom in ethene. 97.6 Remove the n and the square bracket and use the two unattached horizontal bonds to reform the original double bond. 100.3 Polyvinyl acetate PVA 100.4 Used for water soluble paints and wood glue. Paper and textile coatings. 100.5 No recycle number. Regarded as scrap plastic, not worth recycling. 101. H 101.1 H H 0-c-c H O n 103.7 Lactose is the predominant sugar in milk and enzymes turn it into lactic acid. Also produced by the fermentation of plant materials. 103.8 No. A polyester is formed from a co-polymer which is a combination of two polymers, one being a carboxylic acid and the other being an alcohol. 103.9 Two different monomers combine to form the repeat unit. 104.1 Being a bioplastic made from the fermentation of plant materials, it is biodegradable. 104.2 PLA is used for food and cosmetic packaging, agricultural sheeting and household appliances. 104.3 Yes. With limited access to oxygen gas in the air when covered in a landfill dump, it does not biodegrade quickly. H H H cc n H H H cc vinyl chloride monomer H repeat unit monomer

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