An exothermic reaction has an absolute activation energy of . The total thermodynamic heat released — Chemical Kinetics Chemistry Question
Question
An exothermic reaction has an absolute activation energy of $30 \text{ kJ mol}^{-1}$. The total thermodynamic heat released is exactly $\Delta H = -20 \text{ kJ mol}^{-1}$. What is the absolute activation energy barrier for the reverse endothermic pathway?
Answer: D
💡 Solution & Explanation
Deploying the universal master relationship $\Delta H = E_{a(f)} - E_{a(b)}$. We insert the known values, taking special care with the negative exothermic sign: $-20 = 30 - E_{a(b)}$. Structurally rearranging to isolate the unknown precisely yields $E_{a(b)} = 30 - (-20) = 50 \text{ kJ mol}^{-1}$.
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