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Alkanes

Chemistry: AQA GCSE Higher, topic 7.1.3

Alkanes

Hydrocarbons are organic compounds made of carbon and hydrogen. Hydrocarbons are the dominant compounds in crude oil. Most of these hydrocarbons are alkanes.

Alkane structure

Alkane structure

  • In alkanes, carbon atoms bond to four atoms (hydrogen or carbon).
  • We call them saturated hydrocarbons as all their bonds with other atoms are single bonds.
Alkane uses

Alkane uses

  • Alkanes have quite low reactivity, but they combust quite well.
  • This makes them useful as fuels.
General formula

General formula

  • Alkanes have the general formula CnH(2n+2)
    • E.g. if a hydrocarbon contained 7 carbon atoms, the number of hydrogen atoms would be (2 x 7) + 2 = 16
  • So, the formula for the hydrocarbon shown in the image would be C7H16

Test yourself on Alkanes

  • What is the molecular formula of an alkane with 10 carbon atoms?

  • What two elements are hydrocarbons made from?

  • Select the correct statement in each pair about the number of hydrogen atoms in alkanes

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