Question:

The reaction rate constants of two reactions follow Arrhenius' law. The activation energies of Reaction 1 and Reaction 2 are \(E_1\) and \(E_2\), respectively, and \(E_1 < E_2\). Assuming the same value of the frequency factor for both reactions, which one of the following statements is CORRECT?

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Compare \(d(\ln k)/dT = E/(RT^2)\) for the two reactions at the same T; the T-dependent part cancels out when you take the ratio between reactions.
Updated On: Jul 17, 2026
  • Reaction 1 and Reaction 2 are less temperature sensitive at lower temperature than at higher temperature.
  • Reaction 1 and Reaction 2 have the same temperature sensitivity at all temperatures.
  • Reaction 1 is more temperature sensitive than Reaction 2 at all temperatures.
  • Reaction 2 is more temperature sensitive than Reaction 1 at all temperatures.
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The Correct Option is D

Solution and Explanation

Step 1: Write the Arrhenius equation for the rate constant.
\[ k = A_0 \exp\left(-\frac{E}{RT}\right) \]
Step 2: Define temperature sensitivity mathematically.
\[ \frac{d(\ln k)}{dT} = \frac{E}{RT^2} \]
Step 3: Check how temperature affects sensitivity of a single reaction.
For fixed E, sensitivity decreases as T increases. Option A claims the opposite and is incorrect.
Step 4: Compare the two reactions at the same temperature.
\[ \frac{(d(\ln k)/dT)_2}{(d(\ln k)/dT)_1} = \frac{E_2}{E_1} > 1 \]
Since E1<E2, this ratio always exceeds 1, at every temperature.
Step 5: Eliminate the remaining options.
Option B is wrong since the activation energies differ. Option C is the reverse of the correct conclusion.
Step 6: Final answer.
\[ \boxed{\text{Reaction 2 is more temperature sensitive than Reaction 1 at all temperatures}} \]
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