Combustion Reactions:

Reactants: CH₄+ 2O₂                                        Hydrocarbon + Oxygen

Products: CO₂+ 2H₂O                         Carbon dioxide + water

Combustion reactions also more commonly known as burning, is a reaction when hydrocarbons react with oxygen to produce carbon dioxide and water. This reaction requires starting energy such as a spark or a flame to get it going. Combustion is an exothermic reaction which means that it releases heat in the process of reacting. Combustion can be categorized as either complete combustion or either incomplete combustion. Complete combustion is when all of the reactants react and there is no more reactant but 100% product. Burning a candle is an imperfect example of this. Normally when candles are burnt the wax is left over on the surface and we would have to clean it up, But ideally the heat on the candle wick would react with the wax which is a hydrocarbon and using the heat the carbon would react with the oxygen in the air and release carbon dioxide and water and there would be no candle wax left over as all of the wax would react with the oxygen in the air. The other category of combustion is incomplete combustion this is when not all of the product reacts which results in left over residue and the production of carbon monoxide. An example of this is when you burn wood there is left over residue from the wood and carbon monoxide is produced. This type of combustion is also known as dirty combustion because there is always left over residue. 

Helmenstine, Anne Marie. “What Is a Combustion Reaction?” Thoughtco., Dotdash, 28 Dec. 2018, www.thoughtco.com/combustion-reactions-604030.