Question

For the reaction,

$2A+B⟶C+D$

based on the following data, find the order of the reaction.

Exp. No.	A mol L ${}^{-1}$	B mol L ${}^{-1}$	Initial rate mol L ${}^{-1}$ min${}^{-1}$
1.	$0.1$	$0.1$	$6\times {10}^{-3}$
2.	$0.3$	$0.2$	$7.2\times {10}^{-2}$
3.	$0.3$	$0.4$	$2.88\times {10}^{-1}$
4.	$0.4$	$0.1$	$2.40\times {10}^{-2}$

• A. $1$
• B. $2$
• C. $3$
• D. $4$

Answer 1

The correct option is C $3$

From experiments $1$ and $4$ , $\left[B\right]$ is kept constant at $0.1M$ and $\left[A\right]$ is increased $4$ times from $0.1M$ to $0.4M$. The rate of the reaction also increases four times from $6\times {10}^{-3}$ M/min to $2.40\times {10}^{-2}$ M/min.
Hence, the order of the reaction with respect to $A$ is $1.$
From experiments $2$ and $3$, $\left[A\right]$ is kept constant at $0.3M$ and $\left[B\right]$ is doubled from $0.2M$ to $0.4M$. The rate of the reaction increases four times from $7.2\times {10}^{-2}$ M/min to $2.88\times {10}^{-1}$ M/min.
Hence, the order of the reaction with respect to $B$ is $2$.
The overall order of the reaction is $1+2=3$.