How would you write a balanced equation for the combustion of octane, C8H18 with oxygen to obtain carbon dioxide and water?

1 Answer
Nov 10, 2015

2C_8H_18 + 25O_2 -> 16CO_2 + 18H_2O

Explanation:

You just have to check the number of atoms of each element is the same in both sides.
You can do it by steps starting with the unbalanced equation

C_8H_18 + O_2 -> CO_2 + H_2O

By making a list of the elements and the number of atoms on each side of the equation

8-C-1
18-H-2
2-O-3

Then as you can see, the molecule with 1 carbon (CO_2) you have to multiply by eight, the molecule with 2 hydrogens (H_2O) you have to multiply it by 9 to be equal to the left. And when you find that you have to multiply by a fraction then you can multiply the whole equation by an integer so you have only integers.