Question

A following mechanism has been proposed for a reaction:
$2A+B$ $\to$ $D+E$
$A+B$ $\to$ $C+D$ (slow)
$A+C$ $\to$ $E$ (fast)
The rate law expression for the reaction is:

• A. r = $k\left[A{]}^2\right[B]$
• B. r = k[A][B]
• C. r = $k[A{]}^2$
• D. r = $k\left[A\right]\left[C\right]$

Answer 1

The correct option is B r = k[A][B]

Slow step is
$A+B$ $\to$ $C+D$ (slow)
Hence, r = $k\left[A\right]\left[B\right]$