Crude oil is a finite resource. Petrol and other fuels are produced from it using fractional distillation. Cracking is used to convert long alkanes into shorter, more useful hydrocarbons.
The alkanes form a homologous series. Like all homologous series, the alkanes:
The general formula for the alkanes is CnH2n+2, where n is the number of carbon atoms in the molecule.
Decane is an alkane. Its molecules contain 10 carbon atoms. Predict the molecular formula of decane and explain your answer.
The formula will be C10H22. This is because n = 10. So, 2n + 2 = (2 × 10) + 2 = 20 + 2 = 22.
Hexane is an alkane. Its molecules contain six carbon atoms. Predict the molecular formula of hexane.
The formula will be C6H14.
The table shows four alkanes, their molecular formulae and their structures.
The ball and stick models on the right show that the covalent bonds are not really at angles of 90°, as shown in the structures.
The alkanes are saturated hydrocarbons: