Question

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

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

Answer 1

Answer: (B)

r $=$ $k\left[A\right]\left[B\right]$

The slowest reaction is rate-determining step and the rate of reaction depends only on the reactants of rate-determining step.

$A+B\to C+D\left(slow\right)$

$Rate,r=k\left[A\right]\left[B\right]$