Calculate the amount of reactant in percent that remains after 60 minutes involved in first order reaction.…
Calculate the amount of reactant in percent that remains after 60 minutes involved in first order reaction. $\left(\mathrm{k}=0.02303\right.$ minute $\left.^{-1}\right)$
$25 \%$
$50 \%$
$75 \%$
$12.5 \%$
Solution
For a first order reaction,
$\begin{aligned}
& k=\frac{0.693}{t_{1 / 2}} \\
& t_{1 / 2}=\frac{0.693}{0.02303}=30 \mathrm{~min}
\end{aligned}$
Percent of reactant that remains after $t_{1 / 2}=50 \%$. $2 \times \mathrm{t}_{1 / 2}=60 \mathrm{~min}$
Therefore, percent of reactant that remains after $2 \mathrm{t}_{1 / 2}=25 \%$