 The last kind of reaction we'll look at for now is the combustion reaction. This classification refers to any reaction where some kind of fuel combines with oxygen and burns to release energy. One of the products of the reaction, sometimes the only product, will be an oxide of the original fuel. The simplest and most obvious example of combustion, in fact the combustion reaction on which the modern industrial age is built, is that of carbon. Carbon, which could be in the form of coal or charcoal, burns in oxygen and it produces carbon dioxide and releases a lot of energy. Another example is a carbon containing fuel such as ethanol. Ethanol molecules, I should say ethanol is what you would more commonly know as alcohol. Ethanol molecules are made up of carbon, hydrogen and oxygen. And when they burn in extra oxygen gas we produce carbon dioxide from the carbon as well as water from the leftover hydrogen and oxygen in the ethanol. This reaction is used in camping stoves, alcohol camping stoves and now some car engines as well since they've started to blend petrol with ethanol. But the fuel could also be a metal. When iron combines with oxygen it also produces an oxide, iron oxide, and it releases energy. Often this reaction happens really slowly and you don't think of it being a combustion since this is the reaction by which iron rusts, iron oxide is rust. But you can see it's a combustion if you speed up the reaction by heating the iron. This picture shows two combustion reactions happening simultaneously. One is the iron particles burning in air and sparkling with heat and light as they do so. Iron powders sometimes used in fireworks to produce this sparkly effect. The other combustion reaction that's going on in this photograph is what's powering the Bunsen burner, the combustion of gas, probably a mixture of methane and other similar carbon based molecules. They are also combusting to produce carbon dioxide and water.