The first-order gaseous reaction $A (g) B (g) + C (g)$ starts with pure A at 300 mmHg in a constant-volume vessel; the total pressure is 408 mmHg after 15 min. Using $ln 2 = 0.693$ , calculate the half-life in minutes (answer to one decimal place).

Numerical answer type, answer in min, tolerance 0.2.

Answer: 23.3 min

p_{A} = 2 P_{0} - P_{t} = 192

mmHg.

k = \frac{1}{15} ln \frac{300}{192} = 0.0298 mi n^{- 1}

, so

t_{1/2} = 0.693/ k = 23.3

min.