Chemical KineticshardMCQ SINGLE⭐ Must-Do

For a highly specific reversible endothermic chemical reaction, the absolute overall enthalpy changeChemical Kinetics Chemistry Question

Question

For a highly specific reversible endothermic chemical reaction, the absolute overall enthalpy change is measured strictly as $\Delta H = +20 \text{ kJ mol}^{-1}$. If the forward activation energy is $E_{a(f)} = 85 \text{ kJ mol}^{-1}$, calculate the exact backward activation energy $E_{a(b)}$.

Answer: B

💡 Solution & Explanation

The fundamental thermodynamic and kinetic potential energy link dictates that the Enthalpy of reaction $\Delta H = E_{a(f)} - E_{a(b)}$. Substituting the established numeric parameters yields $+20 = 85 - E_{a(b)}$. Rearranging immediately provides $E_{a(b)} = 85 - 20 = 65 \text{ kJ mol}^{-1}$.

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