Question

For a reaction:
$3A\to$ products
It is found that the rate of reaction doubles when the concentration of $A$ is increased by four times. What is the order of the reaction?

• A. $1$
• B. $\frac{1}{2}$
• C. $\frac{3}{2}$
• D. $2$

Answer 1

The correct option is B $\frac{1}{2}$

Rate = $k[\text{Reactant}{]}^n$
Here:
$r_1=k[A{]}^n.......(1)$
$r_2=2r_1=k[4A{]}^n.......(2)$
where $r_1$ is the rate of the reaction
Now dividing equation $\left(2\right)$ by equation $\left(1\right)$, we get,
$2=[4{]}^n$
$\Rightarrow n=\frac{1}{2}$