The rate constant for first order reaction is $0.02232 \mathrm{~min}^{-1}$. Calculate the time required for…

The rate constant for first order reaction is $0.02232 \mathrm{~min}^{-1}$. Calculate the time required for $75 \%$ completion of the reaction.
  1. $62 \cdot 12 \mathrm{~min}$
  2. $\ 28.31 \mathrm{~min}$
  3. $12.77 \mathrm{~min}$
  4. $\ 48 \cdot 12 \mathrm{~min}$

Solution

If $[\mathrm{A}]_{0}=100, \quad[\mathrm{~A}]_{\mathrm{t}}=100-75=25$ $\mathrm{k}=0.02232 \min ^{-1}, \quad t=?$ $t=\frac{2.303}{k} \log \frac{[\mathrm{A}]_{0}}{[\mathrm{~A}]_{t}}=\frac{2.303}{0.02232} \log \frac{100}{25}$ $\therefore t=62.12 \min$

Asked in: MHT CET 2020 (14 Oct Shift 2)

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