Chemical Kinetics Question 10
Question 10 - 2024 (31 Jan Shift 2)
$\mathrm{r}=\mathrm{k}[\mathrm{A}]$ for a reaction, $50 %$ of $\mathrm{A}$ is decomposed in 120 minutes. The time taken for $90 %$ decomposition of $\mathrm{A}$ is _________ minutes.
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Answer: (399)
Solution:
$ \mathrm{r}=\mathrm{k}[\mathrm{A}] $
So, order of reaction $=1$
$ \mathrm{t}_{1 / 2}=120 \mathrm{~min} $
For $90 %$ completion of reaction
$ \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} $
