Question

In the reaction $NH_{4}NO_{2}\left(aq\right)\to N_{2}\left(g\right)+2H_{2}O\left(l\right)$ the volume of $N_2$ after 20 min and after a long time is $40$ ml and $70$ ml respectively. The value of rate constant is :

• A. $\left(1/20\right)In\left(7/4\right) min^{-1}$
• B. $\left(2.303/1200\right)log\left(7/3\right) sec^{-1}$
• C. $\left(1/20\right)log\left(7/3\right) min^{-1}$
• D. $\left(2.303/20\right)log\left(11/7\right) min^{-1}$

Answer 1

Answer: (B)

$NH_{4}NO_{2}\left(aq\right)\to N_{2}\left(g\right)+2H_{2}O\left(l\right)$
$K=\frac{2.303}{t}log\left(\frac{V_{\infty}-V_{O}}{V_{\infty}-V_{t}}\right)$
$\Rightarrow V_{0}=0 \Rightarrow K=\frac{2.303}{20}log \left(\frac{70-0}{70-40}\right)$
$=\frac{2.303}{20}log\left(\frac{70}{30}\right)$
$\Rightarrow K=\frac{2.303}{1200}log\frac{7}{3}$