The key difference between combustion and explosion is that combustion is a chemical reaction that produces heat and gases slowly for a certain time period, whereas explosion is a chemical reaction that produces heat and gases rapidly in an instant.
Combustion and explosion are two important chemical reactions in physical chemistry. These two processes are similar in the final product types that they give. However, they are different from each other chemically, and we can easily distinguish a combustion from an explosion.
CONTENTS
1. Overview and Key Difference
2. What is Combustion
3. What is Explosion
3. Similarities Between Combustion and Explosion
4. Combustion vs Explosion in Tabular Form
5. Summary – Combustion vs Explosion
What is Combustion?
Combustion is a chemical reaction in which substances react with oxygen, producing energy. Here, energy is produced in two forms as light energy and heat energy. We call this “burning.” The light energy appears as a flame, while heat energy is released into the environment.
Figure 01: Combustion
There are two types of combustion as complete and incomplete combustion. In complete combustion, there is an excess of oxygen, and it gives a limited number of products, i.e. when we burn fuel, complete combustion gives carbon dioxide and water with heat energy. Incomplete combustion, on the other hand, is a partial burning process that gives more products at the end of the reaction. Here, a low amount of oxygen is used; if we burn fuel, incomplete combustion of fuel gives carbon dioxide, carbon monoxide, and water with heat. The production of this energy through combustion is very important in industries, and this process is also important to produce fire.
What is Explosion?
An explosion is a rapid expansion of the volume that is associated with an extremely vigorous outward release of energy. This usually takes place along with the generation of a high temperature and the release of high-pressure gases. Detonations are supersonic explosions that form from strong explosives. The energy released from this type of explosion tends to travel through shock waves. Moreover, there are subsonic explosions. These are created from low explosives. The explosions in this type of low explosives occur through a slow combustion process: deflagration.
Figure 02: Explosions
Typically, the force released from an explosion tends to be perpendicular to the surface of the explosive. When considering the velocity of the explosive reaction, we can easily distinguish it from a normal combustion reaction. In a normal combustion reaction, heat is generated, and some gases are released; however, during an explosion, the generation of heat and release of gases occur rapidly. This rapid release of heat and gases can cause the building up of a sudden substantial pressure, which causes the explosion. Moreover, an explosion reaction initiates with the application of heat, shock, or a catalyst. Fragmentation is an important step that takes place during an explosion. This step involves the accumulation and projection of particles as a result of the high explosive detonation. These fragments are created from parts of structures such as glass, roofing material, etc. In addition, fragmentation can also be caused by the destruction of the casing of the explosive material and the loose miscellaneous items that are not vaporized during the explosion.
What are the Similarities Between Combustion and Explosion?
- Combustion and explosion generate heat energy.
- Both reactions release gases.
- They are useful as sources of energy.
What is the Difference Between Combustion and Explosion?
Combustion and explosion are two important chemical reactions in physical chemistry. These two processes are similar in the final product types that they give. The key difference between combustion and explosion is that combustion is a chemical reaction that produces heat and gases slowly for a certain time period, whereas the explosion is a chemical reaction that produces heat and gases rapidly in an instant.
The below infographic presents the differences between combustion and explosion in tabular form for side by side comparison.
Summary – Combustion vs Explosion
Combustion is a chemical reaction in which substances react with oxygen, producing energy. An explosion is a rapid expansion of the volume that is associated with an extremely vigorous outward release of energy. The key difference between combustion and explosion is that combustion is a chemical reaction that produces heat and gases slowly for a certain time period, whereas an explosion is a chemical reaction that produces heat and gases rapidly/suddenly in an instant.
Reference:
1. “Combustion.” Encyclopædia Britannica, Encyclopædia Britannica, Inc.
Image Courtesy:
1. “Et baal” By Einar Helland Berger – Own work (CC BY-SA 2.5) via Commons Wikimedia
2. “Explosions” By PDphoto.org – (Public Domain) via Commons Wikimedia