Crude oilAlkanes

Crude oil is a finite resource. It can be separated into its useful fractions by fractional distillation. Some fractions undergo cracking to help meet demand for the smaller molecules.

Part ofChemistry (Single Science)Chemicals of the natural environment

Alkanes

Crude oil is mostly made up of a group of called the .

A is a series of molecules which:

  • have the same
  • differ by CH2 in the of neighbouring compounds
  • show a gradual variation in
  • have similar chemical properties

The table shows four alkanes, their molecular formula, displayed formula and ball-and-stick model diagram.

Table showing four alkanes, their molecule formulae and their structures

General formula

The formula of any alkane can be worked out using the general formula CnH2n+2 where n = the number of carbon atoms.

For example, for a hydrocarbon with ten carbon atoms:

  • n = 10 and 2n+2 = 22
  • the formula is C10H22

Question

Work out the formula for a hydrocarbon molecule with 6 carbon atoms.