# Describe a combustion equation in general terms

ndnordic | High School Teacher | (Level 2) Associate Educator

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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

bloo786 | Student, Grade 10 | (Level 1) eNoter

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

1. water
2. carbondioxide
3. energy

sultlete | Student | (Level 1) Honors

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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).