Combustion is a rapid oxidation chemical process that is accompanied by low energy release in the form of heat and light. For this process to take place, the presence of a fuel, an oxidizer and heat is necessary. The material that is capable of burning and combines with oxygen is known as fuel. In ordinary combustion the fuel is a compound substance, such as hydrocarbons (petroleum gas, gasoline, kerosene, paraffin, etc.). Oxygen, an essential element for the oxidation process to occur and continue, is known as an oxidizer.
What is Combustion
Table of Contents
Combustion is defined as a rapid oxidation chemical reaction, that which is accompanied by a low release of energy in the form of heat and light. For this process to take place, the presence of a fuel, an oxidant and heat is necessary.
Any substance capable of burning under certain conditions is called combustion. As well as any matter that can burn or undergo rapid oxidation.
Types of combustion
The reaction created by the components of combustion; the combustible material and the oxidant, is disclosed in three types of reaction, which are the following:
Complete combustion
This combustion reacts when the combustible material is completely oxidized and consumed, then other oxygenated compounds are by-produced, such as sulfur dioxide, carbon dioxide, or water vapor.
Stoichiometric combustion
This is the name given to complete combustions, which occur when methane is transformed into CO2 and H2O, use the correct amounts of oxygen for their reaction and which generally occur only in the controlled environment of a laboratory, making use of required instruments. For example, in the case of powdered methane, the combustion spoon is used.
Incomplete combustion
It is those in which half oxidized compounds (also called unburned) appear from combustion gases, such as carbon monoxide (CO), hydrogen, carbon particles, etc.
Combustion process
The fuel must reach a minimum temperature for it to burn, this temperature is called the flash point or flash point. Combustible materials have a temperature low inflammation and enter easily combusted.
If coal or sulfur are burned in equal amounts, it will be observed that the heat energy released by coal is greater than that released by sulfur. This means that fuels, when burned, do not give off equal amounts of heat. There are some that give off a lot of heat energy, while others less heat.
As a result of the process, the products of combustion are obtained. These depend on the nature of the fuel, but in general water vapor, carbon dioxide and carbon are produced. The fact that significant amounts of energy are released when burning fuel gives these materials particular importance, as they can be used for our use.
Industries, factories and electricity production plants use combustion to derive the energy they require to function. Currently, hydrocarbons occupy the first place among energy sources.
Combustion products
Smoke
It is made up of solid and liquid particles suspended in the air. With sizes between 0.005 and 0.01 millimicrons. This has irritating effects on the mucosa.
Smoke is practically the first risk factor in the development of a fire, before you can feel the effect of increasing the temperature. There are then:
- White Smoke: combustion of vegetable products, forages, feed, etc.
- Yellow smoke: chemicals that contain sulfur, fuels that contain hydrochloric and nitric acid.
- Gray smoke: cellulosic compounds, artificial fibers, etc.
- Light black smoke: rubber.
- Dark black smoke: oil, acrylic fibers, etc.
Likewise, the smoke will mix with toxic gases that will modify its color:
- White smoke: burns freely.
- Flame: the temperature varies depending on factors such as the type of fuel and the concentration of oxidant.
- Heat: Heat is a difficult form of energy, which will raise the temperature.
Examples of combustion
A waxed candle: at first, the chemical reaction occurs only in the candlestick. However, once the flame reaches the wax, a reaction also occurs in the wax.
Wood Burning - The hydrocarbons in wood combine with oxygen to form water and carbon dioxide. This is a very energetic reaction, so it generates large amounts of heat and light to release that energy.
A lit match: When a match is rubbed against a slightly rough surface, the friction generates such heat in the match head (consisting of phosphorus and sulfur) that it produces a flame. This is an incomplete reaction because there is residue from the match wax paper.
Burning coal: when burning coal, it reacts and turns from a solid to a gas. In this reaction, energy is released in the form of heat.
Fireworks: when lights firework, the heat causes chemicals in it react with oxygen in the atmosphere to produce heat and light. It can be said that it is an incomplete reaction.
Campfire: Campfires are examples of the type of reaction that occurs between dry leaves, paper, firewood or any other hydrocarbon and a load of caloric energy (such as a lit match or a spark generated by stones).
Gas Stove - Gas stoves run on propane and butane. These two gases, when in contact with an initial charge of heat energy (a phosphor, for example), burn. It is a complete reaction, because it does not generate waste, here it can cause spontaneous combustion.
Forest fires: Forest fires are examples of uncontrolled reactions. As with firewood, they are incomplete reactions because they leave residues.
Strong bases and organic matter: regarding these materials such as caustic soda, it reacts when it comes into contact with organic matter.
Wisps: Wisps are spontaneous flames that are generated in swamps with a high content of decomposing organic matter.
Fuels in engines: the internal combustion engine is used in cars that carry hydrocarbons to be able to function within the combustion chamber, gasoline being one of the main components for the internal reaction to take place.
Combustion of methanol: Also known as methyl alcohol, it is an example of a perfect reaction, because it does not generate anything other than water and carbon dioxide.
Combustion of metallic magnesium: This is an example of a reaction in which neither water nor carbon dioxide is released. In this case, the product is magnesium oxide. It is an incomplete combustion as it produces magnesium oxide.
Explosives - Explosives, such as gunpowder and nitroglycerin, generate the combustion reaction and occur in milliseconds. It should be noted that there are weak and strong explosives.
Gunpowder - Gunpowder is a weak explosive. In the case of weak explosives, they must be placed in confined spaces (such as a gun room) in order for them to function.
Combustion Images
Next, we will show you some combustion images and the different results obtained in each one of them:
Frequently Asked Questions about Combustion
How does combustion occur?
It occurs through a rapid oxidation chemical reaction that is accompanied by a low release of energy in the form of heat and light. For this process to take place, the presence of a fuel, an oxidant and heat is necessary.
What is combustion for?
It is widely used in devices that help move people from one place to another (cars, buses, airplanes, boats, etc.). In the same way, it is also used in homes to fulfill multiple functions, such as in gas stoves or gasoline stoves to cook food, in candles that are sometimes used to light, etc.
What is live combustion?
They are those that consume fuel in the most violent way and, in addition to a high rate of heat, generate light. For example a lit candle, a match or a fire.
What is needed for combustion to occur?
To produce a chemical reaction, you need a fuel, an oxidant and reach the so-called ignition temperature, that is, you need an element that burns (fuel) and another that produces a reaction (oxidant) and generally oxygen in the form of gaseous O2.
What are the reactions of combustion?
The chemical reaction releases a large amount of energy in the form of heat (thermal energy) that, consequently, leads to an expansion of gases (carbon dioxide and water vapor) creating a flame, which is the incandescent gaseous mass that reflects heat and light, and is in contact with the combustible substance.
