Question

The rate constant for a first order reaction is $4.606\times {10}^{–3}{s}^{–1}$. The time required to reduce $2.0g$ of the reactant to $0.2g$ is:

• A. 500 s
• B. 1000 s
• C. 100 s
• D. 200 s

Answer 1

The correct option is A 500 s

$t=\frac{1}{k}\text{ln}\frac{C_{\circ }}{C_t}$
$=\frac{1}{4.606\times {10}^{-3}}\times 2.303\text{log}\frac{2}{0.2}$
$=\frac{1}{2\times {10}^{-3}}\text{log}10$
$=500\text{sec}$