(A) The reaction is a first-order reaction because the unit of the rate constant is $s^{-1}$.For a first-order reaction,the time taken is given by the

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(A) The reaction is a first-order reaction because the unit of the rate constant is $s^{-1}$.For a first-order reaction,the time taken is given by the formula: $t = \frac{2.303}{k} \log \frac{[A]_0}{[A]_t}$.Given: $k = 0.03 \ s^{-1}$,$[A]_0 = 7.2 \ mol \ L^{-1}$,$[A]_t = 0.9 \ mol \ L^{-1}$.$t = \frac{2.303}{0.03} \log \frac{7.2}{0.9} = \frac{2.303}{0.03} \log 8$.Since $\log 8 = \log 2^3 = 3 \log 2 = 3 \times 0.301 = 0.903$.$t = \frac{2.303 \times 0.903}{0.03} \approx 69.3 \ s$.

Class 12 Chemistry Chemical Kinetics First Order reaction

Medium

If the rate constant of a reaction is $0.03 \ s^{-1}$,how much time does it take for $7.2 \ mol \ L^{-1}$ concentration of the reactant to get reduced to $0.9 \ mol \ L^{-1}$ (in $s$)? (Given: $\log 2 = 0.301$)

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$69.3$
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$23.1$
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$210$
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$21.0$

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Chemical Kinetics

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First Order reaction

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If the rate constant of a reaction is $0.03 \ s^{-1}$,how much time does it take for $7.2 \ mol \ L^{-1}$ concentration of the reactant to get reduced to $0.9 \ mol \ L^{-1}$ (in $s$)? (Given: $\log 2 = 0.301$)

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$A$ first order reaction is $50 \%$ complete in $16 \ min$. How much time is required to complete $87.5 \%$ of the reaction (in $min$)?

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