Question

The half-life for the second-order decomposition of HI is 15.4 s when the initial concentration of HI is 0.67 M. What is the rate constant for this reaction? A) 1.0 * 10-2 M-15-1 B) 4.5 * 10-2 M-15-1 C) 9.7* 10-2 M-15-1 OD) 2.2 * 10-2 M-15-1

Answer 1

Answer:

The correct answer is option C.

Explanation:

Half life for second order kinetics is given by:

$t_{\frac{1}{2}=\frac{1}{k\times A_0}$

$t_{\frac{1}{2}$ = half life = 15.4 s

k = rate constant =?

$A_0$ = initial concentration = 0.67 M

$15.4 s=\frac{1}{k\times 0.67 M}$

$k=\frac{1}{15.4 s\times 0.67 M}=0.09692 M^{-1} s^{-1}=9.69\times 10^{-2}M^{-1} s^{-1}\approx 9.7\times 10^{-2} M^{-1} s^{-1}$

$9.7\times 10^{-2} M^{-1} s^{-1}$  is the rate constant for this reaction.