Question

In the reaction NH4NO2 (aq.) $\rightarrow$ N2 (g) + 2 H2O (l) the volume of N2 after 20 min and after a long time is 40 ml and 70 ml respectively. The value of rate constant is :

• A. (1/20) In (7/4) min–1
• B. (2.303 /1200) log (7/3) sec–1
• C. (1/20) log (7/3) min–1
• D. (2.303 / 20) log (11/7) min–1

Answer 1

Answer: (B)

(2.303 /1200) log (7/3) sec–1

Answer 2

$\text{N}\text{H}_{4}\text{N}\text{O}_{2}\ (\text{aq})\ \overset{\quad\quad}{\rightarrow}\text{ }\text{N}_{2}\ (g)\text{ + 2}\text{H}_{2}\text{O }(\mathcal{l})$

$K = \frac{2.303}{t}\log\left( \frac{V_{\infty} - V_{O}}{V_{\infty} - V_{t}} \right) \Rightarrow V_{0} = 0 \Rightarrow K = \frac{2.303}{20}\log\left( \frac{70 - 0}{70 - 40} \right) = \frac{2.303}{20}\log\left( \frac{70}{30} \right) \Rightarrow K = \frac{2.303}{1200}\log\frac{7}{3}$