Calculate the enthalpy of the following homogeneous gaseous reaction:<br><br>from the following data — Thermodynamics and Thermochemistry Chemistry Question
Question
Calculate the enthalpy of the following homogeneous gaseous reaction:<br>$\text{CH}_3\text{COCH}_3 + 2\text{O}_2 \to \text{CH}_3\text{COOH} + \text{CO}_2 + \text{H}_2\text{O}$<br>from the following data:<br>Bond energies (kJ/mol): C–H = 414; C–C = 348; C=O = 580; C–O = 354; O=O = 610; O–H = 462;<br>Magnitude of resonance energies (kJ/mol): $\text{COOH} = 118; \text{CO}_2 = 140$.
Answer: D
💡 Solution & Explanation
Total bond energy of reactants = $[6(414) + 2(348) + 580] + 2(610) = 4980\text{ kJ/mol}$. Total bond energy of products = $[3(414) + 348 + 580 + 354 + 462] + 2(580) + 2(462) = 5070\text{ kJ/mol}$. Theoretical $\Delta H = 4980 - 5070 = -90\text{ kJ/mol}$. Resonance stabilizes products further: $\Delta H_{\text{actual}} = -90 - 118 - 140 = -348\text{ kJ/mol}$.
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