Question

Rate law expression for the conversion of $H_2$ and $I_2$ to HI at ${400}^{\circ }C$ of the following mechanisms:
$H_2+I_2\to 2HI$ (one step)

• A. $rate$ $=$ $K\left[H_2\right]\left[I_2\right]/[HI{]}^2$
• B. $rate$ $=$ $\left[HI{]}^2/K\right[H_2\left]\right[I_2]$
• C. $rate$ $=$ $K\left[H_2\right]\left[I_2\right]$
• D. None of these

Answer 1

The correct option is C $rate$ $=$ $K\left[H_2\right]\left[I_2\right]$

The conversion of $H_2$ and $I_2$ to $HI$ at ${400}^{\circ }C$ is given by the following reaction:

$H_2+I_2\to 2HI$ (one step)

$Rate$ $=$ $K\left[H_2\right]\left[I_2\right]$.

The reaction is first order in hydrogen and first order in iodine. In the rate law expression, the concentration terms for hydrogen and iodine are raised to power $1$ each.