Question

The rate constant for the reaction, $2N_2{O}_5\to 4N{O}_2+O_2$ is $2\times {10}^{-5}{s}^{-1}$. If rate of reaction is $1.4\times {10}^{-5}mol{L}^{-1}{s}^{-1}$, what will be the concentration of $N_2{O}_5$ in mol $L^{-1}$?

• A. $0.8$
• B. $0.7$
• C. $1.2$
• D. $1$

Answer 1

The correct option is B $0.7$

$Rate=k\left[N_2{O}_5\right]$ (first order as unit of rate constant is $s^{-1}$)
$\left[N_2{O}_5\right]=\frac{rate}{k}=\frac{1.4\times {10}^{-5}mol{L}^{-1}{s}^{-1}}{2\times {10}^{-5}{s}^{-1}}=0.7mol{L}^{-1}$.