Question

A reaction was found to be second order with respect to the concentration of carbon monoxide. If the concentration of carbon monoxide is doubled, with everything else kept the same, the rate of reaction will be

• A. Remains unchanged
• B. Tripled
• C. Increases by a factor of $4$
• D. Doubled

Answer 1

The correct option is C Increases by a factor of $4$

Second-order rate expression would be
$r=k[A{]}^2$
Since the given reaction is second order with respect to the concentration of carbon monoxide,
$\therefore r=k[CO{]}^2$
When the concentration of $CO$ is double then,
$r=K\left(2\right[CO]{)}^2$
$\Rightarrow r=4k[CO{]}^2$
Thus, according to the rate law expression, when the concentration of carbon monoxide is doubled, the rate of reaction increases by a factor of four.