Question

The reaction $N_2{O}_5$ (in $CC{l}_4$) $\to 2N{O}_2+1/2O_2\left(g\right)$ is the first order in $N_2{O}_5$ with rate constant $6.2\times {10}^{-4}{S}^{-1}$.

What is the value of the rate of reaction when $N_2{O}_5=1.25mole{L}^{-1}$ ?

• A. $7.75\times {10}^{-4}mol{L}^{-1}{S}^{-1}$
• B. $6.35\times {10}^{-3}mol{L}^{-1}{S}^{-1}$
• C. $5.15\times {10}^{-5}mol{L}^{-1}{S}^{-1}$
• D. $3.85\times {10}^{-4}mol{L}^{-1}{S}^{-1}$

Answer 1

Answer: (A)

$7.75\times {10}^{-4}mol{L}^{-1}{S}^{-1}$

For the first-order reaction, the rate of the reaction is given by the expression

Rate $=k\left[N_2{O}_5\right]$ where k is the rate constant.

Substitute values in the above expression

Rate $=6.2\times {10}^{-4}{S}^{-1}\times 1.25mole{L}^{-1}=7.75\times {10}^{-4}mol{L}^{-1}{S}^{-1}$

So, the correct option is $A$