A combustion reaction involves a substance, usually a hydrocarbon, reacting rapidly with oxygen to produce energy in the form of heat and light. One of the most common examples is the combustion of butane, which is a simple hydrocarbon.To illustrate, in the exercise above, butane (\(\mathrm{C}_{4} \mathrm{H}_{10}(g)\)) is the compound that combusts. When it reacts with oxygen (\(\mathrm{O}_{2}(g)\)), the products are carbon dioxide (\(\mathrm{CO}_{2}\)) and water (\(\mathrm{H}_{2}\mathrm{O}\)). To balance a combustion reaction, follow these steps:
- Balance carbon atoms first by ensuring the number of carbon atoms in the reactant equals those in the \(\mathrm{CO}_{2}\) produced.
- Next, balance hydrogen atoms, ensuring the hydrogen in the hydrocarbon equals twice the number in \(\mathrm{H}_{2}\mathrm{O}\) produced.
- Finally, balance oxygen atoms by adjusting the number of \(\mathrm{O}_{2}\) molecules to match the total oxygen found in \(\mathrm{CO}_{2}\) and \(\mathrm{H}_{2}\mathrm{O}\).
In the combustion of butane:\[2 \mathrm{C}_{4} \mathrm{H}_{10} + 13 \mathrm{O}_{2} \rightarrow 8 \mathrm{CO}_{2} + 10 \mathrm{H}_{2} \mathrm{O}\] This balanced equation represents a perfectly efficient combustion reaction, releasing energy primarily in heat and light.