Question

The half life for a given reaction was doubled as the initial concentration of the reactant was doubled. The order of the reaction is:

• A. $zero$
• B. $1st$
• C. $2nd$
• D. $3rd$

Answer 1

Answer: (A)

$zero$

We know that half life is related to concentration as:

$t_{\frac{1}{2}}=[A{]}^{1-n}$ where $n$ is the order of the reaction

Here $n=2$

$t_{\frac{1}{2}}=[A{]}^{1-2}=\frac{1}{\left[A\right]}$

For n=0, $t_{\frac{1}{2}}$ $=[A{]}^{1-0}=[A]$

If $t_{\frac{1}{2}}$ is doubled, $\left[A\right]$ is also doubled then the reaction is of zero order.