A zero-order decay reaction operates with a half-life given an initial starting concentration of . H — Chemical Kinetics Chemistry Question

💡 Solution & Explanation

For zero-order, $t_{1/2} = [A]_0 / 2k$. Plugging in data: $6 = 0.2 / 2k \Rightarrow k = 0.2 / 12 = 1/60 \text{ M h}^{-1}$. To drop from $0.5 \text{ M}$ to $0.2 \text{ M}$, the consumed mass $x = 0.3 \text{ M}$. Because $x = kt$, the elapsed time $t = x / k = 0.3 / (1/60) = 18 \text{ hours}$.