How Does the Collision Theory Work

The collision theory was put forth in the years 1916 and 1918, by Max Trautz and William Lewis respectively. The basis of the theory and the explanation about how does the collision theory work, lies in the understanding of the molecular behavior of the particles reacting with each other.

Facts about Collision Theory

The basic principle on which the collision theory is based, is that for a chemical reaction to take place, the particles involved in the reaction must collide with each other. Although the theory proposes that collision of particles is mandatory for the reaction to take place, according to certain facts, it is not necessary that all the reacting particles possess the required energy to connect effectively during the collision.

Working of Collision

For a reaction to take place, energy is considered to be the basic need. During a chemical reaction, the existing bonds by which the reactants are joined to each other, break down and form new ones. A minimum amount of energy is necessary for the above process to take place. This energy is termed as 'activation energy'. During a chemical reaction, energy is released as the reactants collide with each other. The rate of the chemical reaction depends upon factors such as temperature and the density of the particles. However, even after an increase in temperature, there is not much effect on the rate of collision of the reacting particles.

The collision theory is based on the assumption that whenever the nuclei of two reactants come close to each other and within a certain specified limit, collision between these particles takes place. Let's consider an example of a chemical reaction where two particles, 'A' and 'B' react with each other. A 'cross-section' area is the area surrounding the particle 'A', where it collides with the particle 'B'. The reaction is successful only if the collision takes place in this cross-section.

Collision Orientation

To understand the orientation of the process of collision, let us consider a chemical reaction that takes place between ethene (CH2=CH2) and HCl. The reaction between the molecules of these elements results into the formation of chloroethane (CH3CH3Cl). In the above reaction, the double bond between carbon atoms is broken and converted into a single bond. For the chemical reaction to be successful, hydrogen atoms must be aligned in such a manner that they bond with carbon atoms only. Any other form of alignment or orientation won't result in the formation of chloroethane. Thus, the orientation of molecules or atoms is of utmost importance in the collision and subsequently for the reaction to be fruitful.

The applications of the collision theory are generally studied with the help of chemical reactions which involve gases. There are many advantages of studying and understanding the collision theory. It would be possible for us to foresee or predict and alter the rate of chemical reactions that we conduct, by studying the collision theory. Thus, the collision theory is important from the point of view of future research.