6. ORGANIC CHEMISTRY
6.2 ALKANES
(a) describe an homologous series as a group of compounds with a general formula, similar chemical properties and showing a gradation in physical properties as a result of increase in the size and mass of the molecules, e.g. melting and boiling points; viscosity; flammability
(b) describe the alkanes as an homologous series of saturated hydrocarbons with the general formula CnH2n+2
(c) draw and name the structures of branched and unbranched alkanes, C1 to C4
(d) define isomerism and identify isomers
(e) describe the properties of alkanes (exemplified by methane) as being generally unreactive except in terms of burning and substitution by chlorine
(f) suggest how ‘cracking’ can be used to obtain more useful alkanes and alkenes of lower Mr from larger hydrocarbon molecules
6.3 ALKENES
(a) describe the alkenes as an homologous series of unsaturated hydrocarbons with the general formula CnH2n
(b) draw and name the structures of branched and unbranched alkenes, C2 to C4
(c) describe the manufacture of alkenes and hydrogen by cracking hydrocarbons and recognise that cracking is essential to match the demand for fractions containing smaller molecules from the refinery process
(d) describe the difference between saturated and unsaturated hydrocarbons from their molecular structures and by using aqueous bromine
(e) describe the properties of alkenes (exemplified by ethene) in terms of combustion, polymerisation and the addition reaction with bromine, steam and hydrogen
(f) state the meaning of polyunsaturated when applied to food products
(g) describe the manufacture of margarine by the addition of hydrogen to unsaturated vegetable oils to form a solid product
