Fire is a chemical reaction that gives off light and heat. It is one of the most familiar examples of the chemical process of oxidation.
Fire is very hot. A person should never touch fire because fire may burn anything that gets too close. If human skin touches fire, the skin may blister which can take some time to heal. If a fire occurs, the mouth should be covered with a wet cloth because if too much smoke is breathed in, it is possible to faint.
Fire can be very useful if it is treated carefully. It has always been very important for people to be able to make fire, because people need heat on cold days and to cook things. Its light is also useful to be able to see in dark places.
If fire is not treated carefully, it can be very dangerous. A fire that got out of control once destroyed 17,400 km2, an area the size of New York City, in the United States. Forests can burn down if fires are not controlled. Every year, large areas of forests are destroyed because of fire, particularly in Europe. This usually happens in summer. Firefighters or firemen are people with special training to stop fires, or to keep a fire under control.
Fire needs three things to burn: oxygen, fuel, and heat. Fuels can be wood, tinder, coal, oil or any other substance that will easily oxidize. Once a fire is burning, it creates its own heat, which allows the fire to keep burning on its own for some time.
A fire can be stopped in three different ways, by removing any of the three things it needs to burn:
- The fuel can be removed. If a fire burns through all of its fuel and extra nearby fuel is removed, the fire will stop burning.
- The oxygen can be removed. This is called "smothering" a fire. Fires cannot burn in a vacuum or if they are covered in carbon dioxide.
- The heat can be removed. The most common way to remove heat is to use water to absorb the heat, putting the fire out.
However, some fires cannot be smother, such as magnesium flames. They can burn in CO2, nitrogen, and some other elemental compounds, although they cannot burn in noble gases such as helium.
Fires are usually combustion reactions that take carbon, hydrogen, and oxygen. The products are very commonly water, and carbon dioxide, although there are other examples that avoid this generalization, such as burning magnesium in air, which makes magnesium oxide. Fires can occur in many ways and there are many types of fire which, if not treated correctly, can cause total devastation. There are wood fires, gas fires, metal fires, and more.
Wood fires can be put out with water used to absorb the heat, but metal fires are too hot for water to absorb enough heat to put out the fire. If water is used to extinguish a metal fire, the water will simply evaporate. For metal fires, sand can be used to coverd the fire and choke it off from obtaining oxygen. A fire extinguisher can put out most fires.