Question

The composition of $N_2{O}_5$ is first order reaction represented by: $N_2{O}_5\to N_2{O}_4+1/2O_2.$
After 20 min the volume of $O_2$ poduced is 10 mL and at the end of the reaction 40 mL. The rate constant is equal to:

• A. $\frac{1}{20}ln\frac{30}{50}$
• B. $\frac{1}{20}ln\frac{50}{30}$
• C. $\frac{1}{20}ln\frac{50}{40}$
• D. $\frac{1}{20}ln\frac{40}{30}$

Answer 1

Answer: (D)

$\frac{1}{20}ln\frac{40}{30}$

$k=\frac{2.303}{t}log\frac{V_{\infty }}{V_{\infty }-V_t}$
or $k=\frac{1}{t}ln\frac{V_{\infty }}{V_{\infty }-V_t}$
$k=\frac{1}{20}ln\frac{40}{(40-10)}$
$=\frac{1}{20}ln\frac{40}{30}$