Question

The reaction, $ N_{2}O_{5} $ in $ CCl_{4} \text{(solution)}\rightarrow 2NO_{2}\text{(solution)}+\frac{1}{2}O_{2}(g) $
is of first order in $ N_{2}O_{5} $ with rate constant $ 6.2\times 10^{-4}s^{-1}. $
What is the value of rate of reaction when $ [N_{2}O_{5}]=1.25\,mol\,L^{-1} $ ?

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

Answer 1

Answer: (C)

For first order reaction,
Rate $=k\left[ N _{2} O _{5}\right]$
$=6.2 \times 10^{-4} s ^{-1} \times 1.25\, mol\, L ^{-1} $
$=7.75 \times 10^{-4} mol \,L ^{-1} s ^{-1}$