Question

Define order of reaction. How will you find out the order of reaction of the reaction nA + mB $\rightarrow$ xC + yD?

Hint:

Remember that the order of a reaction is always determined experimentally. It may or may not be the same as the stoichiometric coefficients of the balanced chemical equation.

Answer 1

Definition of order of reaction:
The order of a reaction is the sum of the powers of the concentrations of the reactants in the rate law expression of the reaction.
It indicates how the rate of reaction depends on the concentration of the reactants.
General reaction:
\[ nA + mB \;\longrightarrow\; xC + yD \]
The rate law for this reaction can be written as:
\[ r = k [A]^{\alpha} [B]^{\beta} \]
Where:
- \( k \) = rate constant,
- \( \alpha \) = order of reaction with respect to A,
- \( \beta \) = order of reaction with respect to B.
Overall order of reaction:
\[ \text{Order} = \alpha + \beta \]
Experimental determination:
The values of \( \alpha \) and \( \beta \) are not necessarily equal to the stoichiometric coefficients \( n \) and \( m \).
They are determined experimentally using methods such as:
1. Initial rate method: By measuring the rate of reaction for different initial concentrations of A and B, the powers \( \alpha \) and \( \beta \) are calculated.
2. Integrated rate equations: By analyzing the concentration of reactants as a function of time, the order of reaction can be established.
Thus, the order of reaction of \( nA + mB \rightarrow xC + yD \) is given by the sum of experimentally determined powers \( \alpha + \beta \).
\[ \boxed{\text{Order of reaction} = \alpha + \beta} \]