Note:

IGCSE Chemistry Topic Questions Paper 4 Extended Theory for Organic Chemistry.

The exam aims to test you on the following concepts:

• 14.1 Names of compounds

Core 

• Name and draw the structures of methane, ethane, ethene, ethanol, ethanoic acid and the products of the reactions stated in sections 14.4–14.6 
• State the type of compound present, given a chemical name ending in -ane, -ene, -ol, or -oic acid or a molecular structure

Supplement 

• Name and draw the structures of the unbranched alkanes, alkenes (not cis-trans), alcohols and acids containing up to four carbon atoms per molecule 
• Name and draw the structural formulae of the esters which can be made from unbranched alcohols and carboxylic acids, each containing up to four carbon atoms

14.2 Fuels

Core 

• Name the fuels: coal, natural gas and petroleum 
• Name methane as the main constituent of natural gas 
• Describe petroleum as a mixture of hydrocarbons and its separation into useful fractions by fractional distillation 
• Describe the properties of molecules within a fraction 
• Name the uses of the fractions as: – refinery gas for bottled gas for heating and cooking – gasoline fraction for fuel (petrol) in cars – naphtha fraction for making chemicals – kerosene/paraffin fraction for jet fuel – diesel oil/gas oil for fuel in diesel engines – fuel oil fraction for fuel for ships and home heating systems – lubricating fraction for lubricants, waxes and polishes – bitumen for making roads

14.3 Homologous series

Core 

• Describe the concept of homologous series as a ‘family’ of similar compounds with similar chemical properties due to the presence of the same functional group

Supplement 

• Describe the general characteristics of a homologous series
• Recall that the compounds in a homologous series have the same general formula 
• Describe and identify structural isomerism

14.4 Alkanes

• Core 

Describe the properties of alkanes (exemplified by methane) as being generally unreactive, except in terms of burning 

Describe the bonding in alkanes

Supplement

• Describe substitution reactions of alkanes with chlorine

14.5 Alkenes

Core 

• Describe the manufacture of alkenes and of hydrogen by cracking 
• Distinguish between saturated and unsaturated hydrocarbons: – from molecular structures – by reaction with aqueous bromine
• Describe the formation of poly(ethene) as an example of addition polymerisation of monomer units

Supplement 

• Describe the properties of alkenes in terms of addition reactions with bromine, hydrogen and steam 14.6 Alcohols Core • Describe the manufacture of ethanol by fermentation and by the catalytic addition of steam to ethene • Describe the properties of ethanol in terms of burning • Name the uses of ethanol as a solvent and as a fuel Supplement • Outline the advantages and disadvantages of these two methods of manufacturing ethanol

14.7 Carboxylic acids

Core 

• Describe the properties of aqueous ethanoic acid

Supplement 

• Describe the formation of ethanoic acid by the oxidation of ethanol by fermentation and with acidified potassium manganate(VII) 
• Describe ethanoic acid as a typical weak acid 
• Describe the reaction of a carboxylic acid with an alcohol in the presence of a catalyst to give an ester

14.8 Polymers

14.8.1 Polymers

Core

• Define polymers as large molecules built up from small units (monomers) Supplement • Understand that different polymers have different units and/or different linkages

14.8.2 Synthetic polymers

Core

• Name some typical uses of plastics and of man-made fibres such as nylon and Terylene 
• Describe the pollution problems caused by non-biodegradable plastics Supplement • Explain the differences between condensation and addition polymerisation 
• Deduce the structure of the polymer product from a given alkene and vice versa
• Describe the formation of nylon (a polyamide) and Terylene (a polyester) by condensation polymerisation, the structure of nylon 
• Name proteins and carbohydrates as constituents of food Supplement • Describe proteins as possessing the same (amide) linkages as nylon but with different units 
• Describe the structure of proteins
• Describe the hydrolysis of proteins to amino acids. (Structures and names are not required.)
• Describe complex carbohydrates in terms of a large number of sugar units,
• Describe the hydrolysis of complex carbohydrates (e.g. starch), by acids or enzymes to give simple sugars 
• Describe the fermentation of simple sugars to produce ethanol (and carbon dioxide). (Candidates will not be expected to give the molecular formulae of sugars.) 
• Describe, in outline, the usefulness of chromatography in separating and identifying the products of hydrolysis of carbohydrates and proteins