So for our present purposes, it will be helpful to use a simplifying model. The simple possible model is one in which a single compound is used to represent the gasoline mixture, and the most common choice for that compound is octane, C8H18. If we start by assuming that gasoline can be represented reasonably by octane,then it is fairly easy to write and balance a chemical equation for its combustion. If we further assume complete combustion, then our equation should show octane and oxygen as reactants, and carbon dioxide and water as products.