✓ Board-verified
Chemistry · 2024 · 3 marks
CBSE 2024 · Region 5 · Set 3 · Q28
The rate constant of a reaction quadruples when the temperature changes from 700 K to 720 K. Calculate the activation energy for this reaction. [ log…
The rate constant of a reaction quadruples when the temperature changes from $\displaystyle 700$ K to $\displaystyle 720$ K . Calculate the activation energy for this reaction. $\displaystyle \left[\log 2=0.30, \log 4=0.60,2.303 \mathrm{R}=19.15 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\right]$
Marking-scheme solution
\[\log \frac{k_{2}}{k_{1}}=\frac{E_{a}}{2.303 \mathrm{R}}\left(\frac{T_{2}-T_{1}}{T_{1} T_{2}}\right)
\]
It is given that, \(\displaystyle k_{2}=4 k_{1}\)
Therefore, \(\displaystyle \log \frac{4 k_{1}}{\dot{k}_{1}}=\frac{E_{a}}{19.15}\left(\frac{720-700}{700 \times 720}\right)\)
\(\displaystyle 0.60=\frac{20 \times E_{a}}{19.15 \times 700 \times 720}\)
\(\displaystyle 0.60=\frac{20 \times E_{a}}{19.15 \times 700 \times 720}\)\(\displaystyle E_{a}=\frac{0.60 \times \dfrac{19.15}{20} \times 700 \times 720}{20}\)
\(\displaystyle =289548 \mathrm{~J} \mathrm{~mol}^{-1}\)
\(\displaystyle =289.5 \mathrm{~kJ} \mathrm{~mol}^{-1}\)
All Chemical Kinetics questions2024 question paperNCERT solutions: Chemical KineticsPractice Chemical Kinetics →
More from Chemical Kinetics
- Assertion: Order of reaction is applicable to elementary as well as complex reactions. Reason (R): For a complex reaction molecularity has no meaning.2023 · asked 2×
- For the reaction 3 A → 2 B, rate of reaction +(d[B])/dt is equal to2023 · asked 2×
- Assertion: For a zero order reaction the unit of rate constant and rate of reaction are same. Reason (R): Rate of reaction for zero order reaction is…2023 · asked 2×
- Assertion: Hydrolysis of an ester follows first order kinetics. Reason (R): The concentration of water does not get altered much during the reaction.2025
- Show that the time required for 99.9 % completion in a first order reaction is 10 times of half-life (t_1 / 2) of the reaction [ log 2=0.3010, log…2024
- In the given reaction N_2( g)+3 H_2( g) → 2 NH_3( g) the rate of formation of NH_3 is 3 · 6 × 10^-4 mol L^-1 s^-1. Calculate the (i) rate of…2022
- Reactant 'A' underwent a decomposition reaction. The concentration of 'A' was measured periodically and recorded in the table given below: Based on…2025
- Which of the following curve represents the first order reaction?2026
CBSE Class 12 Chemistry past-paper question from the 2024 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.