## Order of a Reaction – Class 12 | Chapter – 4 | Chemistry Short Notes Series PDF for NEET & JEE

Order of a Reaction: The order of a reaction determines how the rate of the reaction changes with changes in the concentration of the reactants. If the order of a reaction is 1, then doubling the concentration of the reactant doubles the rate of the reaction. If the order is 2, then doubling the concentration of the reactant quadruples the rate of the reaction.

## Order of a Reaction

The order of a chemical reaction is defined as the power to which the concentration of each reactant is raised in the rate equation. It is determined experimentally by measuring the rate of the reaction under different conditions, such as changing the concentration of one or more reactants while keeping others constant.

For example, consider the following reaction:

A + B → C

If the rate of this reaction depends on the concentration of A raised to the power of 2 and the concentration of B raised to the power of 1, then the overall order of the reaction is 3 (2+1). This can be expressed in a rate equation as follows:

Rate = k[A]2[B]

Where k is the rate constant and [A] and [B] represent the concentrations of A and B, respectively.

The order of a reaction can also be fractional, such as 1/2 or 3/4. In such cases, the reaction rate depends on the square root or the fourth root of the concentration of the reactants, respectively.

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