The enthalpy of formation of ammonia gas is –46.0 kJ/mol. The enthalpy change for the reaction:<br> — Thermodynamics and Thermochemistry Chemistry Question
Question
The enthalpy of formation of ammonia gas is –46.0 kJ/mol. The enthalpy change for the reaction:<br>$2\text{NH}_3\text{(g)} \to \text{N}_2\text{(g)} + 3\text{H}_2\text{(g)}$ is
Answer: B
💡 Solution & Explanation
The given reaction is the exact reverse of the formation reaction for 2 moles of ammonia. $\Delta H = -2 \times \Delta H_f = -2 \times (-46.0\text{ kJ/mol}) = +92.0\text{ kJ}$.
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