$\mathrm{r}=\mathrm{k}[\mathrm{A}]$ for a reaction, $50 \%$ of $\mathrm{A}$ is decomposed in 120 minutes. The time taken for $90 \%$ decomposition of $\mathrm{A}$ is _________ minutes.
Answer (integer)
399
Solution
<p>$\mathrm{r}=\mathrm{k}[\mathrm{A}]$</p>
<p>So, order of reaction $=1$</p>
<p>$\mathrm{t}_{1 / 2}=120 \mathrm{~min}$</p>
<p>For $90 \%$ completion of reaction</p>
<p>$$\begin{aligned}
& \Rightarrow \mathrm{k}=\frac{2.303}{\mathrm{t}} \log \left(\frac{\mathrm{a}}{\mathrm{a}-\mathrm{x}}\right) \\
& \Rightarrow \frac{0.693}{\mathrm{t}_{1 / 2}}=\frac{2.303}{\mathrm{t}} \log \frac{100}{10} \\
& \therefore \mathrm{t}=399 \mathrm{~min} .
\end{aligned}$$</p>
About this question
Subject: Chemistry · Chapter: Chemical Kinetics · Topic: Rate of Reaction
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