Question

For the elementary reaction $2A+B\to$ products, the rate of reaction is $6.0\times {10}^{-3}$ mol/lit-sec. The rate of reaction changes to $1.2\times {10}^{-2}$ mol/lit-sec when:

• A. concentration of A and B are doubled
• B. concentration of B is doubled
• C. concentration of A is doubled
• D. concentration of B is tripled

Answer 1

Answer: (B)

concentration of B is doubled

$2A+B\to products$
$Rate=K\left[A{]}^2\right[B]$
$6.0\times {10}^{-3}=K\left[A{]}^2\right[B]$ -----(1)
$1.2\times {10}^{-2}=K\left[n_{1}A{]}^2\right[n_{2}B]$ -----(2)
$\left(2\right)÷\left(1\right)$
$2=\left[n_1{]}^2\right[n_2]$
$n_1=1,n_2=2$
So, concentration of $B$ is doubled.