# Describe a combustion equation in general terms

### 3 Answers | Add Yours

A combustion reaction involves any fuel which can combine with oxygen to produce both carbon dioxide and water.

The general form is:

Fuel + O2 --> CO2 + HOH

To balance a combustion reaction, use this method:

Example reaction: C4H8 + O2 --> CO2 + HOH

1. Balance the number of carbon atoms on both sides using coefficients.

C4H8 + O2 --> 4 CO2 + HOH

2. Balance the number of hydrogen atoms on both sides of the equation using coefficients.

C4H8 + O2 --> 4 CO2 + 4 HOH

3. Balance the oxygen atoms. You have 8 oxygen in the CO2 + 4 in the water for a total of 12 oxygen atoms on the right. Divide the 12 by 2 ( you have two already on the left) and you get 6.

Now complete balancing:

C4H8 + 6 O2 --> 4 CO2 + 4 HOH

Here is a simple way to remember. Whenever you hear about combustion remember that three things are fixed and are bound to be formed.

- water
- carbondioxide
- energy

Combustion, particularly that of Hydrocarbons, i.e. butene, octane etc, in a reaction, (usually involving heat) will always give a resultant product of Carbon Dioxide (CO2) and Water (H2O).