A reaction which is of first order w.r.t. reactant $\mathrm{A}$, has a rate constant $6 \mathrm{~min}^{-1}$.…

A reaction which is of first order w.r.t. reactant $\mathrm{A}$, has a rate constant $6 \mathrm{~min}^{-1}$. If we start with $[\mathrm{A}]=$ $0.5 \mathrm{~mol} \mathrm{~L}^{-1}$, when would [ $\mathrm{A}$ ] reach the value of $0.05 \mathrm{~mol} \mathrm{~L}^{-1}$
  1. $0.384 \mathrm{~min}$
  2. $0.15 \mathrm{~min}$
  3. $3 \mathrm{~min}$
  4. $3.84 \mathrm{~min}$

Solution

$t=\frac{2.303}{k} \log \frac{a}{a-x}$
$=\frac{2.303}{6} \log \frac{0.5}{0.05}=0.384 \mathrm{~min}$

Asked in: JEE-TOPICTESTS-CHEMISTRY

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