State the postulates of collision theory. Explain the effects of temperature, concentration, and catalyst on the rate of reaction.
State the postulates of collision theory. Explain the effects of temperature, concentration, and catalyst on the rate of reaction.
The important postulates of the collision theory are:
1. A collision must occur between the molecules of reacting gases for a reaction to occur.
2. But all collisions do not lead to the formation of the products.
3. The colliding molecules must possess minimum energy so that their collisions lead to the formation of the products (reaction to occur). It is referred to as threshold energy.
4. Most of the molecules at STP generally possess energy less than this threshold energy. Such molecules are referred to as normal molecules. The difference in the energy between the threshold energy and the energy of the normal colliding molecules is referred to as activation energy.
Activation energy threshold energy The energy of normal colliding molecules
5. Every reaction under the given experimental conditions will have its characteristic or specific value of the activation energy.
Effect of concentration: With the increase in the concentration of the reactants, the number of reactant molecules per unit volume increases. Furthermore, the number of collisions increases, which results in a net increase in effective collisions. Therefore, the rate of a reaction increases.
Effect of temperature: For most of the chemical reactions, the rate of the reaction increases with an increase in the number of effective collisions. When the temperature increases, the kinetic energy of molecules increases. More molecules attain threshold energy thereby increasing the number of fruitful collisions and hence, the rate of reaction.
Effect of catalyst: The chemical reactions can be carried out at a faster rate by increasing the temperature, but this is not possible in the case of all reactions. Moreover, some reactions can be carried out at a lower temperature by using a catalyst. Since the process takes place at a lower temperature, the cost of production gets reduced. A catalyst increases the rate of reaction by providing an alternative path for the reaction.
The important postulates of the collision theory are:
1. A collision must occur between the molecules of reacting gases for a reaction to occur.
2. But all collisions do not lead to the formation of the products.
3. The colliding molecules must possess minimum energy so that their collisions lead to the formation of the products (reaction to occur). It is referred to as threshold energy.
4. Most of the molecules at STP generally possess energy less than this threshold energy. Such molecules are referred to as normal molecules. The difference in the energy between the threshold energy and the energy of the normal colliding molecules is referred to as activation energy.
Activation energy threshold energy The energy of normal colliding molecules
5. Every reaction under the given experimental conditions will have its characteristic or specific value of the activation energy.
Effect of concentration: With the increase in the concentration of the reactants, the number of reactant molecules per unit volume increases. Furthermore, the number of collisions increases, which results in a net increase in effective collisions. Therefore, the rate of a reaction increases.
Effect of temperature: For most of the chemical reactions, the rate of the reaction increases with an increase in the number of effective collisions. When the temperature increases, the kinetic energy of molecules increases. More molecules attain threshold energy thereby increasing the number of fruitful collisions and hence, the rate of reaction.
Effect of catalyst: The chemical reactions can be carried out at a faster rate by increasing the temperature, but this is not possible in the case of all reactions. Moreover, some reactions can be carried out at a lower temperature by using a catalyst. Since the process takes place at a lower temperature, the cost of production gets reduced. A catalyst increases the rate of reaction by providing an alternative path for the reaction.
