Define the following terms :
(a) Order of a reaction
(b) Activation energy
Ans. (a) Order of a reaction: The order of a reaction refers to the exponent to which the concentration of a reactant is raised in the rate equation. It defines how the rate of a chemical reaction depends on the concentration of reactants. The order can be determined experimentally and can be zero, first, second, or higher order.
For example, in a zero-order reaction, the rate of the reaction is independent of the concentration of the reactants. In a first-order reaction, the rate of the reaction is directly proportional to the concentration of one reactant. In a second-order reaction, the rate of the reaction is proportional to the square of the concentration of one reactant or to the product of the concentrations of two reactants.
(b) Activation energy: Activation energy is the minimum amount of energy that must be overcome for a chemical reaction to occur. It represents the energy barrier that reactant molecules must overcome to transform into product molecules during a chemical reaction.
In a reaction mechanism, the activation energy is the energy difference between the energy of the activated complex (transition state) and the energy of the reactants. Higher activation energy implies a slower reaction rate because it requires more energy for the reactant molecules to reach the transition state. Activation energy is a key parameter in determining the rate of a chemical reaction.
