Consider an exothermic reaction A k₋₁k₁⇌ I as the temperature increases · ABC26PH0472
Subject: Physical Chemistry · Chapter: Chemical Kinetics · Topic: Chemical Kinetics – General · Exam: GATE 2005-2021 · Marks: 2 · Difficulty: Easy
Consider an exothermic reaction $\mathrm{A} \underset{\mathrm{k}_{-1}}{\stackrel{\mathrm{k}_{1}}{\rightleftharpoons}} \mathrm{I}$ as the temperature increases
(a)$\mathrm{k}_{1}, \mathrm{k}_{-1}$, and $\mathrm{k}_{1} / \mathrm{k}_{-1}$ increases
(b)$\mathrm{k}_{1}$ increases, $\mathrm{k}_{-1}$ decreases, and $\mathrm{k}_{1} / \mathrm{k}_{-1}$ increases.
(c)$\mathrm{k}_{1}, \mathrm{k}_{-1}$ increases and $\mathrm{k}_{1} / \mathrm{k}_{-1}$ decreases
(d)$\mathrm{k}_{1}$ and $\mathrm{k}_{-1}$ decrease, and $\mathrm{k}_{1} / \mathrm{k}_{-1}$ increases.
Answer
Answer: C ✓ checked by 4AB · confidence high
The source book printed no answer; this one was worked out and checked — see the explanation.
Explanation
Both rate constants rise with temperature (Arrhenius). For an exothermic step the reverse reaction has the larger activation energy, so k₋₁ rises faster and K = k₁/k₋₁ falls (van 't Hoff).