A first order reaction has a rate constant $0.00813 \mathrm{~min}^{-1}$. How long will it take for $60 \%$…
A first order reaction has a rate constant $0.00813 \mathrm{~min}^{-1}$. How long will it take for $60 \%$
completion?
$98.7 \mathrm{~min}$
$56.35 \mathrm{~min}$
$112.7 \mathrm{~min}$
$62 \cdot 77 \mathrm{~min}$
Solution
Original amount of reactant $=100$
$[\mathrm{A}]_{t}=$ Reactant remaining unreacted $=100-60=40$
For first order reaction,
$\therefore t=\frac{2.303}{0.00813 \mathrm{~min}^{-1}} \log _{10} \frac{100}{40}=112.7 \mathrm{~min}$