Question

A hypothetical reaction :
$A_2+B_2\to 2AB$ follows the following mechanism :
$A_2\iff A+A\left(fast\right)$....K
$A+B_2\to AB+B\left(slow\right)$
$A+B\to AB\left(fast\right)$
The order of the overall reaction is

• A. 2
• B. $\frac{3}{2}$
• C. 1

Answer 1

The correct option is B $\frac{3}{2}$

$Rate=k\left[A\right]\left[B_2\right]ButK=\frac{[A{]}^2}{\left[A_2\right]}or\left[A\right]=\sqrt{K.\left[A_2\right]}Rate=k.\sqrt{K}.\sqrt{A_2}.\left[B_2\right]=k[A_2{]}^{\frac{1}{2}}.[B_2]\therefore Order=1+\frac{1}{2}=\frac{3}{2}$