Octane (C8H18) vapor burns to produce carbon dioxide gas with water vapor. What is the balanced equation?

Answer 1

Combustion reactions require oxygen gas.

C8H18 + O2 ==> CO2 + H2O ... UNBALANCED

C8H18 + O2 ==> 8CO2 + H2O ... Carbons are balanced

C8H18 + O2 ==> 8CO2 + 9H2O ... Carbons and hydrogens are balanced

C8H18 + 12.5 O2 ==> 8CO2 + 9H2O ... Carbons, hydrogens and oxygens are balanced, BUT...

To get rid of the fraction (12.5) applied to the O2, multiply everything by 2 to arrive at...

2C8H18 + 25 O2 ==> 16CO2 + 18H2O ... BALANCED EQUATION