What is or are needed for a substance to burn?

Answer 1

Three things are needed for a fire: a fuel, an oxidant and heat. So, if you want a substance to burn, you have to provide an oxidant, almost always the oxygen of the air, and heat it up to where it will start burning. For instance, if you want a piece of paper to burn, it's already in the air and you apply a lighted match to it. However, if you want rocket fuel to burn in outer space, you have to have a supply of oxygen, or a chemical which provides oxygen on the rocket as well. Gasoline in a car is vaporised and mixed with air in the carburettor, and then a spark is applied to the mixture in the cylinder.Conversely, if you want to put a fire out, you remove one of the three ingredients. If you put water on a wood fire, you are removing heat. If you throw a fire blanket over a fire, or smother a camp fire with soil, you are removing oxygen. If you want to put a bunsen burner out, you turn off the gas, thus removing the fuel. To control a forest fire, fighters will often cut a fire break to prevent the flames from spreading.

Answer 2

The simple answer is the gas oxygen as, in normal life when most things burn they combine with the oxygen in the air in a violent way - that we call a flame. For example, paper and wood, which is made of mostly carbon, hydrogen and oxygen, burns in oxygen to form carbon dioxide and hydrogen oxide (water vapour). Magnesium metal burns in air to form a white powder magnesium oxide. However, there are many forms of burning and other gases can allow things to burn in them. As one example, if hot iron wool is placed into a jar of chlorine gas, it will burn well with a yellowy orange flame producing brown iron chloride. Similarly, hot sodium metal will also burn in chlorine with a ight yellow flame to produce white sodium chloride - or common salt! Other gases also allow burning - we all know that if a jet of natural gas (mostly methane) is set alight in the air it will burn well. However, if you fill a large container with natural gas and introduce a jet of air into it, you can actually set the air alight where the air itself will burn in the natural gas. So, the simple answer to the question is that oxygen is needed for burning, but burning - or 'combustion' is not as simple as one might think as the above examples show.

Answer 3

oxygen