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?4.5 × 10-2 M-1s-11.0 × 10-2 M-1s-12.2 × 10-2 M-1s-13.8 × 10-2 M-1s-19.7 × 10-2 M-1s-1

Answer 1

Answer: $9.7\times 10^{-2}M^{-1}s^{-1}$

Explanation:

Half life is the amount of time taken by a radioactive material to decay to half of its original value.

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

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

$k=9.7\times 10^{-2}M^{-1}s^{-1}$

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