Chemical reactions burning butane

However, fossil fuels do not burn automatically. Energy, usually in the form of heat or light, is needed to get the chemical reaction started. The combustion of hydrocarbon fuels requires this input of energy, called activation energy, to begin the reaction. For example, the butane gas in a disposable lighter requires a spark to start the combustion of the gas. 

All the laws you have learned so far involving gases can be applied to calculate the stoichiometry of reactions in which gases are reactants or products. Recall that the coefficients in chemical equations represent molar amounts of substances taking part in the reaction. For example, when butane gas burns, the reaction is represented by the following chemical equation. 

---