Question

Volume of $N_2$ (in cc)	Time (in minutes)
6.25	10
9	15
11.4	20
13.65	25
35.05	$\infty$

The following data is for the decomposition of ammonium nitrite in aqueous solution.

The order of the reaction is:

• A. zero
• B. one
• C. -one
• D. -two

Answer 1

Answer: (B)

one

Assume the reaction to be a first-order $r\times n$.

Initial concentration of $N_2$ is at $T_{\infty }=35.05cc$

For the first-order reaction

$k=\frac{2.303}{t}\log \frac{{\left[N_2\right]}_o}{{\left[N_2\right]}_o-\left[N_t\right]}$

$att=10sec$

$k=\frac{2.303}{10}\log \frac{35.05}{28.80}=0.0196$

$att=15sec$

$k=\frac{2.303}{15}\log \frac{35.05}{26.05}=0.0198$

$att=20sec$

$k=\frac{2.303}{20}\log \frac{35.05}{23.65}=0.0197$

$att=25sec$

$k=\frac{2.303}{25}\log \frac{35.05}{21.40}=0.0197$

Since the value of k is constant, the reaction is of order 1.

Hence, the correct option is $B$