11.1 Formulae, functional groups and terminology
1. What does a displayed formula of a molecule show?
It shows all the atoms and all the bonds.
2. What is the general formula for the homologous series of alkanes?
CnH2n+2
3. What is the general formula for the homologous series of alkenes?
CnH2n
4. State the general formula for alcohols.
CnH2n+1OH
5. State the general formula for carboxylic acids.
CnH2n+1COOH
6. Define a functional group.
An atom or group of atoms that determine the chemical properties of a homologous series.
7. What is a structural formula?
An unambiguous description of the way the atoms in a molecule are arranged.
8. Provide examples of structural formulae for ethene, ethanol, and methyl ethanoate.
CH2=CH2 (ethene), CH3CH2OH (ethanol), and CH3COOCH3 (methyl ethanoate).
9. Define structural isomers.
Compounds with the same molecular formula but different structural formulae.
10. Give an example of structural isomers for the molecular formula C4H10.
CH3CH2CH2CH3 and CH3CH(CH3)CH3.
11. Define a homologous series.
A family of similar compounds with similar chemical properties due to the presence of the same functional group.
12. What is a saturated compound?
A compound whose molecules have only single carbon–carbon bonds.
13. What is an unsaturated compound?
A compound whose molecules have one or more carbon–carbon bonds that are not single bonds.
14. List the five general characteristics of a homologous series.
(a) having the same functional group; (b) having the same general formula; (c) differing from one member to the next by a -CH2- unit; (d) displaying a trend in physical properties; (e) sharing similar chemical properties.
11.2 Naming organic compounds
15. Name the specific organic compounds for which you must be able to draw displayed formulae.
Methane, ethane, ethene, ethanol, and ethanoic acid.
16. How do you identify the type of compound present from its chemical name?
By the ending of the name: -ane (alkane), -ene (alkene), -ol (alcohol), or -oic acid (carboxylic acid).
17. For unbranched alkanes, alkenes, alcohols, and carboxylic acids, up to how many carbon atoms per molecule must you be able to name and draw?
Up to four carbon atoms per molecule.
18. Name the two specific unbranched alkenes you must be able to draw and name.
But-1-ene and but-2-ene.
19. Name the four specific unbranched alcohols you must be able to draw and name.
Propan-1-ol, propan-2-ol, butan-1-ol, and butan-2-ol.
20. What are esters made from?
Unbranched alcohols and carboxylic acids.
11.3 Fuels
21. Name the three fossil fuels mentioned in the syllabus.
Coal, natural gas, and petroleum.
22. What is the main constituent of natural gas?
Methane.
23. Define hydrocarbons.
Compounds that contain hydrogen and carbon only.
24. What is petroleum?
A mixture of hydrocarbons.
25. How is petroleum separated into useful fractions?
By fractional distillation.
26. Describe the trend in chain length of petroleum fractions from the bottom to the top of the fractionating column.
Chain length decreases.
27. Describe the trends in volatility, boiling point, and viscosity of fractions from the bottom to the top of the fractionating column.
Volatility becomes higher; boiling points become lower; viscosity becomes lower.
28. State the use for the refinery gas fraction.
Gas used in heating and cooking.
29. State the use for the gasoline/petrol fraction.
Fuel used in cars.
30. What is the use of the naphtha fraction?
It is used as a chemical feedstock.
31. State the use for the kerosene/paraffin fraction.
Jet fuel.
32. State the use for the diesel oil/gas oil fraction.
Fuel used in diesel engines.
33. State the use for the fuel oil fraction.
Fuel used in ships and home heating systems.
11.4 Alkanes
34. State the use for the lubricating oil fraction.
Lubricants, waxes, and polishes.
35. State the use for the bitumen fraction.
Making roads.
36. Describe the bonding in alkanes and their classification as hydrocarbons.
They have single covalent bonding and are saturated hydrocarbons.
37. Describe the general reactivity of alkanes.
They are generally unreactive, except in terms of combustion and substitution by chlorine.
38. Define a substitution reaction.
A reaction in which one atom or group of atoms is replaced by another atom or group of atoms.
39. What type of reaction is the reaction of alkanes with chlorine?
A photochemical reaction.
40. What provides the activation energy (Ea) for the substitution reaction of alkanes with chlorine?
Ultraviolet light.
11.5 Alkenes
41. Describe the bonding in alkenes and their classification as hydrocarbons.
They include a double carbon–carbon covalent bond and are unsaturated hydrocarbons.
42. How are alkenes and hydrogen manufactured?
By the cracking of larger alkane molecules using a high temperature and a catalyst.
43. Why are larger alkane molecules cracked?
To produce smaller, more useful molecules like alkenes and hydrogen.
44. How can you distinguish between saturated and unsaturated hydrocarbons using a chemical test?
By their reaction with aqueous bromine; unsaturated hydrocarbons (alkenes) will decolourise the bromine water.
45. Define an addition reaction.
A reaction in which only one product is formed.
46. Name the three substances that alkenes react with in addition reactions as stated in the syllabus.
Bromine (or aqueous bromine), hydrogen, and steam.
11.6 Alcohols
47. State the conditions required for the addition of hydrogen to an alkene.
The presence of a nickel catalyst.
48. State the conditions required for the addition of steam to an alkene.
The presence of an acid catalyst.
49. Describe the conditions for the manufacture of ethanol by fermentation.
Fermentation of aqueous glucose at 25–35 °C in the presence of yeast and in the absence of oxygen.
50. Describe the conditions for the manufacture of ethanol by the catalytic addition of steam to ethene.
300 °C and 6000 kPa (60 atm) in the presence of an acid catalyst.
51. What are the products of the combustion of ethanol?
Carbon dioxide and water.
52. State two uses of ethanol.
As a solvent and as a fuel.
53. What must you be able to describe regarding the two methods of ethanol manufacture?
Their relative advantages and disadvantages.
11.7 Carboxylic acids
54. Describe the reaction of ethanoic acid with metals, bases, and carbonates.
Ethanoic acid reacts like other acids to produce salts (ethanoates) along with hydrogen (with metals), water (with bases), or water and carbon dioxide (with carbonates).
55. How is ethanoic acid formed using acidified aqueous potassium manganate(VII)?
By the oxidation of ethanol.
56. How is ethanoic acid formed during vinegar production?
By the bacterial oxidation of ethanol.
57. Describe the reaction of a carboxylic acid with an alcohol.
They react in the presence of an acid catalyst to form an ester.
11.8 Polymers
58. Define polymers.
Large molecules built up from many smaller molecules called monomers.
59. What is poly(ethene) an example of?
Addition polymerisation using ethene monomers.
60. What are plastics made from?
Polymers.
61. List the environmental challenges caused by plastics as stated in the syllabus.
Disposal in landfill sites, accumulation in oceans, and the formation of toxic gases from burning.
62. What specific structures must you be able to identify in addition and condensation polymers?
Repeat units and/or linkages.
63. Name the two types of condensation polymers mentioned for which you must deduce structures.
Polyamides and polyesters.
64. What monomers form a polyamide?
A dicarboxylic acid and a diamine.
65. What monomers form a polyester?
A dicarboxylic acid and a diol.
66. Describe the difference between addition and condensation polymerisation.
Addition polymerisation involve monomers with double bonds joining with no other product; condensation polymerisation involves monomers with two functional groups joining and eliminating a small molecule (like water).
67. What type of polymer is nylon?
A polyamide.
68. What type of polymer is PET?
A polyester.
69. What can be done with PET once it has been used?
It can be converted back into monomers and re-polymerised.
70. Describe proteins as polymers.
They are natural polyamides formed from amino acid monomers.
71. What is the general structure of the monomers that form proteins?
Amino acids with the structure H2N-C(R)H-COOH, where R represents different side-chains.