Question

In the reaction $2 A+B \rightarrow A_{2} B$, if the concentration of $A$ is doubled and that of $B$ is halved, then the rate of reaction will

• A. increase by 4 times
• B. decrease by 2 times
• C. increase by 2 times
• D. remains the same

Answer 1

Answer: (C)

increase by 2 times

Answer 2

For the reaction: $2 A+B \rightarrow A_{2} B r=k[A]^{2}[B]$
If concentration of $A$ is doubled and that of $B$ is halved, then
$r'=[2 A]^{2}\left[\frac{B}{2}\right]$
$2 k[A]^{2}[B] r'=2 r$
Hence, if the concentration of
[A] is doubled and
[B] is halved, then rate of reaction increases by 2 times.