It is the consequence of an exothermic chemical combustion reaction between a type of fuel (gasoline, alcohol, wood, among others) and an oxidizer (oxygen), thus releasing light and heat.
What causes fire and what are its components?
For the fire to really happen, three essential elements are needed:
- the fuel: everything that can combust, that is, burn. The most common examples are: wood, plastic, paper, among others;
- the oxidizer: the element that allows burning, that is, that comes into contact with the fuel for combustion to take place. The greatest example of an oxidizer is oxygen;
- the heat: any active energy that will allow combustion between the first two elements.
These three elements together are known as the Fire Triangle, as illustrated in the image below.
Triangle of Fire, with the three main elements: oxygen, heat and fuel.
The process of fire begins when particles of heated material break apart, attaching themselves to the oxygen in the air. From this union arise water molecules, which turn into flame. What is left of this reaction becomes light and heat.
It was only in the 13th century that oxygen was found to be most responsible for fire to happen. Until then, it was believed that this role was the responsibility of a substance called "phlogus", which proved to be non-existent.
Chemical reaction process that produces fire, with wood as fuel and oxidizer as oxygen.
The different colors of fire
The color of the fire is a result of the temperature at which it is burning and, as a result, each part of its flame will have a different color.
Fire light is made up of photons, that is, small particles that act as an electromagnetic wave. The firelight, therefore, is a result of the size of this wave. For each size and temperature, we have a different color.
Waves considered larger are more reddish, while smaller ones are more bluish. In a candle, for example, the base of the flame is more bluish, as it has a lot of energy and heat, with shorter electromagnetic waves.
At the top of a candle flame, we notice that the color is more reddish, as its energy is lower and the photon wave is longer and with less heat.
Example of a candle flame
the origin of fire
More than 400 million years ago, man's first contact with fire was through lightning. When colliding with the wood, the rays caused flames or even large fires.
Noticing the sensation of heat produced by the fire, they began to use the rest of the sparks produced by that shock of lightning in the trees. However, the spark was short-lived and could not meet their daily needs.
The discovery of fire by man and its uses
As they did not know how to produce sparks, man was dependent on the action of lightning for many years. But, more than 300,000 years ago, Homo erectus noticed that by rubbing one stone (or wood) against another, using friction, it could generate sparks.
It was, finally, the discovery of fire. From then on, man began to notice the power that this chemical reaction had and started to use it to:
- Cooking meat: rather, game meat rotted because it was left in its natural state and exposed to the weather. After the discovery of fire, men started to roast them, as they noticed that they lasted longer for consumption.
- Cooking vegetables and greens: some vegetables and vegetables that were previously more difficult to be consumed raw, are now more implemented in the diet with their cooking over the fire. At this point, man's greatest advantage was to consume foods with more nutrients, which, progressively, meant a large reserve of energy in the body, developing new abilities, including the ability to reasoning.
- Heating: the man started to warm up, having greater locomotion power inside and outside the caves.
- Craft development: man also discovered that by mixing the water boiled by fire with the clay, he would be able to develop vessels that served to store water and food;
- Tool development: when they noticed that fire was capable of melting some metals, they began to produce tools such as hammers, knives, spears and cutlery.
Until today, fire is the main source of energy for human beings, being used to produce electricity and heating.
What is the chemical reaction in a matchstick?
The matchstick head has 3 main elements, with important functions for combustion to take place. Are they:
- Antimony Trisulfide: serves as fuel;
- potassium chlorate: a substance that helps fuel burn;
- ammonium phosphate: element that prevents the production of a large amount of smoke.
There is a paraffin wax that helps the flame to travel throughout the match, in addition to the dye, which makes the toothpick's head redden.
In the box, the side surface contains powdered glass, responsible for helping the toothpick friction, and the red match, which allows the fire to ignite.
When the head of the match is rubbed against the box, heat is emitted. This energy converts the red phosphorus contained in the box into white phosphorus, which easily reacts to oxygen in the air.
This same heat emission also causes the potassium chlorate present in the match head burn, reacting to the oxygen present in the air, which, when in contact with the fuel, produces the flame.
See also the meaning of combustion.
The causes and impacts of forest fires
Forest fires can occur in forested areas and in many places around the world. This is one of the biggest concerns of environmentalists, since burning a forest or part of it can bring great losses and consequences for the balance of the environment.
The main causes of forest fires are:
- Natural causes: the very heat and low humidity of certain forest areas, such as the Brazilian cerrado, cause combustion, generating large fires;
- Lack of awareness: cigarettes thrown on the side of the road, poorly extinguished bonfires and balloons are some of those responsible for large forest fires, as they serve as heat sources. This is due to the lack of awareness of the population and local tourism;
- Intentional cause: many cases of fire can be deliberate, especially in the case of hunters looking for certain species of animals.
Image representing a forest fire
The forest has a great ecological role, as it absorbs carbon and provides oxygen to the atmosphere, maintaining the balance of the environment. For this reason, forest fires are a constant concern of environmentalists.
How to prevent forest fires?
The first action to be taken is the educational awareness of the communities that live near the forest areas.
In addition, another important action is that government authorities are available to receive reports of any suspicious attitude in these areas, so that they can avoid large amounts in advance. damage.
Today, many areas with constant forest fires are already prevented in times of drought, which helps in the previous elimination of fire spots.
See also the meaning:
- ecosystem
- Environment
- Ecology
- homo erectus
