Question

How is collision theory related to the rate of reactions?

Answer 1

The collision theory provides us with the ability to predict what conditions are necessary for a successful reaction to take place. The two conditions are Energy condition and the proper orientation. If in any reaction both the conditions are fulfilled properly then the rate of reaction is increased manifold and the reaction is performed with a faster rate.

Complete step-by-step answer:
According to collision theory the reactants collide with one another to bring about the chemical change. During collision old bonds break and the new bonds are formed. If all collisions are effective the reaction will be completed in no time. Hence if collisions are effective then they will gradually increase the rate of reaction.

The effective collisions are those which fulfills the following conditions:

1. Energy condition: The reacting species must have sufficient energy to break the bonds in order to make the collisions effective. The minimum amount of energy possessed by the colliding molecules to bring about the chemical change is called threshold energy. Hence the molecules which have the energy equal or greater than the threshold energy will bring about the chemical reaction quickly.

2)There are three major ways in order to increase energy and in turn rate of reaction. They are
a. increase in temperature
b. increase in pressure and concentration.
c. Increase in surface area

Proper orientation: the reacting molecules must collide in a proper orientation so that the old bonds break and the new bonds are formed. Hence the molecules undergoing the effective collision will increase the rate of reaction.

Note: It may be noted that the molecules with energy above the threshold energy but improper orientation cannot collide effectively. This in turn will slow down the rate of reaction. Hence both the conditions are to be fulfilled properly in order to increase the rate of reaction.