1.1. Alkanes are saturated hydrocarbons which can be used as fuels, lubricants and as starting materials for a wide range of other compounds. The main source of alkanes is petroleum. Petroleum is a mixture of alkanes with different chain lengths, which are separated in a process called fractional distillation.

i) State the meaning of the term saturated hydrocarbon.

ii) Explain why this separation process is called fractional distillation.

1.2. Describe the process of fractional distillation.

1.3. Once the mixture of saturated hydrocarbons has been separated, they can be used as fuels. The high temperatures in a car engine with the presence of oxygen, means that the alkanes burn (combust) to give out heat energy.

Figure 1 below shows the structure of three alkanes.

Figure 1

i) Define the terms complete and incomplete combustion.

ii) Name the alkane in Figure 1 which is most likely to undergo incomplete combustion. Explain your answer.

1.4. The boiling points of the alkanes from Figure 1 are summarised in Table 1 below.

Table 1

Use Table 1 to explain the effect that chain length and branching of molecules has on boiling point.