ChemistryCode 9701
Alkanes
What this topic asks you to be able to do
- recall the routes, with reagents and conditions, for making alkanes: (a) adding hydrogen across an alkene in a hydrogenation reaction, using H2(g), a Pt/Ni catalyst and heat (b) cracking a longer chain alkane by heating it with Al2O3
- describe: (a) how alkanes undergo complete and incomplete combustion (b) how alkanes undergo free-radical substitution with Cl2 or Br2 when ultraviolet light is present, taking the reactions of ethane as the example
- describe the free-radical substitution mechanism through its initiation, propagation and termination steps
- suggest how heavier fractions of crude oil can be cracked to give alkanes and alkenes of lower Mr that are more useful
- understand why alkanes are, in general, unreactive, including towards polar reagents, given the strength of their C–H bonds and the relatively low polarity of those bonds
- recognise the effects on the environment of the unburnt hydrocarbons, carbon monoxide and oxides of nitrogen released when alkanes burn in an internal combustion engine, and the effects of removing them catalytically