Chapter 11, Problem 52QAP

For the zero-order decomposition of ammonia on tungsten

${\text{NH}}_3\left(g\right)\stackrel{\text{W}}{\to }\frac{1}{2}{\text{N}}_2\left(g\right)+\frac{3}{2}{\text{H}}_2\left(g\right)$the rate constant is $2.08\times {10}^{-4}\text{mol}/\text{L}\cdot \text{s}$.

(a) What is the half-life of a 0.250 M solution of ammonia?

(b) How long will it take for the concentration of ammonia to drop from 1.25 M to 0.388 M?