Desorption of a gas from metal surface follows first-order kinetics. The rate constant of desorption — Surface Chemistry Chemistry Question
Question
Desorption of a gas from metal surface follows first-order kinetics. The rate constant of desorption can be given by Arrhenius equation. If the desorption of hydrogen on manganese is found to increase 10 times on increasing the temperature from 600 to 1000 K, the activation energy of desorption is
Answer: B
💡 Solution & Explanation
Using Arrhenius equation: log(k₂/k₁) = (Ea / 2.303R) × (1/T₁ - 1/T₂). Given k₂/k₁ = 10, T₁ = 600 K, T₂ = 1000 K, R ≈ 2 × 10⁻³ kcal/mol K. log(10) = (Ea / (2.303 × 2 × 10⁻³)) × (1/600 - 1/1000). 1 = (Ea / 4.606 × 10⁻³) × (400 / 600000). Ea = (4.606 × 10⁻³ × 600000) / 400 = 6.909 kcal/mol. Therefore, correct answer is B.
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