In the most basic sense, fire is light and heat that is produced from a chemical reaction. The chemical reaction is usually between oxygen and some sort of fuel. Common forms of fuel are wood and gasoline. Wood and gasoline don’t just become fire, in order for the chemical reaction to begin, a third ingredient is needed: heat.
The heat causes the molecules of the fuel to become unstable. Some of the molecules then begin to decompose once they reach a certain temperature. When this happens they release gases creating smoke. Some molecules are moving so quickly from the increase in temperate they “bump” into oxygen molecules cause a flame.
Fire is dangerous because it is a self-perpetuating chemical reaction. The heat of the flame will keep the chemical reaction going as long as there is still oxygen around. Flames can be different colors based on the temperature. The hotter the flame the color is usually blue, cooler flames are orange or yellow. The carbon molecules as they are heated emit light called incandescence.
The gases in the flames of fire are less dense than surrounding air which is why they move upwards towards lower pressure. This is why flames look like they are pointed at the top.
Since fire is made up of three different things, it can be put out in three different ways:
- Removing the fuel source or taking it away
- Removing the oxygen also known as smothering the fire
- Removing the heat by absorbing it with water
Most firefighters use water to remove heat in order to reduce the flames of a fire and prevent the chain chemical reaction from recurring. Fire extinguishers eliminate fires in two ways: by shooting water to remove heat as well as foam to help reduce oxygen.
Fires have been used by human beings for thousands of years. They have used them for heat, for light as well as to cook food. Now that we know what fire is, we can understand fire safety and prevention.