What you’ll learn6 learning objectivesChoose one objective for a focused lesson, or study the complete topic.14.1.1Preparation of alkanes• Recall preparation of alkanes: (a) addition of hydrogen to an alkene in a hydrogenation reaction, H2(g) and Pt/Ni catalyst and heat; (b) cracking of a longer chain alkane, heat with Al2O3Syllabus objective14.1.2Describe• Describe:: (a) the complete and incomplete combustion of alkanes; (b) the free-radical substitution of alkanes by Cl 2 or Br2 with ultraviolet light, as exemplified by the reactions of ethaneSyllabus objective14.1.3Mechanism: free-radical substitution• Describe the mechanism of free-radical substitution using the initiation, propagation and termination stepsSyllabus objective14.1.4Suggest how cracking can be used to obtain• Suggest how cracking can be used to obtain more useful alkanes and alkenes of lower M r from heavier crude oil fractionsSyllabus objective14.1.5The general unreactivity of alkanes• Understand the general unreactivity of alkanes, including towards polar reagents in terms of the strength of the C–H bonds and their relative lack of polaritySyllabus objective14.1.6Combustion pollutants and catalysts• Recognise the environmental consequences of carbon monoxide, oxides of nitrogen and unburnt hydrocarbons arising from the combustion of alkanes in the internal combustion engine and of their catalytic removalSyllabus objective