JEE Main 2022 — Chemistry Physical Chemistry

2022integereasy

$\begin{matrix}[A] & \rightarrow & [B] \\ \mathrm{Reactant} & & \mathrm{Product}\end{matrix}$

If formation of compound $[B]$ follows the first order of kinetics and after $70$ minutes the concentration of $[A]$ was found to be half of its initial concentration. Then the rate constant of the reaction is $x\times {10}^{-6}{s}^{-1}$ . The value of $x$ is____

Official previous-year question

Held on 27 Jul 2022 · Verified 6 Jul 2026.

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Solution

$\begin{matrix}[A] & \rightarrow & [B] \\ \mathrm{Reactant} & & \mathrm{Product}\end{matrix}$

Since the reaction follows the first order kinetics and after $70$ minutes the concentration of $[A]$ was found to be half of its initial concentration. That means 70 minutes is the half life time for the reaction. And we know that for a first order reaction half life time is given as.

${t}_{\frac{1}{2}}=\frac{0.693}{K} K=\frac{0.693}{{t}_{\frac{1}{2}}}=\frac{0.693}{70\times 60\mathrm{sec}.}$

$=\frac{6930}{7\times 6}\times {10}^{-6}{\mathrm{sec}}^{-1} =165\times {10}^{-6}{\mathrm{sec}}^{-1} \mathrm{So},x=165$

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JEE Main 2022 — Chemistry Physical Chemistry

2022integereasy

$\begin{matrix}[A] & \rightarrow & [B] \\ \mathrm{Reactant} & & \mathrm{Product}\end{matrix}$

Official previous-year question

Held on 27 Jul 2022 · Verified 6 Jul 2026.

Did you get this right?

Solution

$\begin{matrix}[A] & \rightarrow & [B] \\ \mathrm{Reactant} & & \mathrm{Product}\end{matrix}$

${t}_{\frac{1}{2}}=\frac{0.693}{K} K=\frac{0.693}{{t}_{\frac{1}{2}}}=\frac{0.693}{70\times 60\mathrm{sec}.}$

$=\frac{6930}{7\times 6}\times {10}^{-6}{\mathrm{sec}}^{-1} =165\times {10}^{-6}{\mathrm{sec}}^{-1} \mathrm{So},x=165$

JEE Main 2022 — Chemistry Physical Chemistry

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JEE Main 2022 — Chemistry Physical Chemistry

Did you get this right?

Solution

Your note

JEE Main Physical Chemistry in other years

More JEE Main Physical Chemistry questions

Other Chemistry topics for JEE Main

Organic Chemistry

Inorganic Chemistry

Keep practicing Physical Chemistry