Question

Define order of reaction.

Answer 1

Hint: It is very important to know how the concentration of the reactants affect the rate of the reaction and this is achieved by the order of the reaction. It is always found through experiments or can be deduced just by looking at the chemical reaction.

Complete step by step solution:
The order of the reaction is the relation between the concentration of the reaction and the rate of the reaction. It can be defined as the power dependence of rate of reaction on the concentration of all the reactants.

Some of the characteristics of order of the reaction are given below.
a) It represents the number of species whose concentration directly affects the rate of the chemical reaction.
b) The order of the reaction can be obtained by the addition of all the exponents of the concentration terms to the rate expression.
c) It does not depend on the stoichiometric coefficients corresponding to the reactants in the balanced chemical equation.
d) The concentration product has no role in determining the order of the reaction.
e) The value of order of reaction can be an integer or a fraction and can even be zero.

There are four types of order reactions.
1. Zero-Order Reactions: The reaction rate and the concentration of reactants are independent to each other.
2. First-Order Reactions: The reaction rate depends upon the concentration of only one reactant.
3. Pseudo First-Order Reactions: The concentration of one reactant remains constant and is included in the rate expression.
4. Second Order Reactions: When the reaction order is 2, the reaction is a second-order reaction.

Note: When the reaction order is a fraction, then the reaction is generally said to be a chain reaction. In this case, it can also undergo some complex processes.