Ethanol can undergo decomposition to form two sets of products:<br><br><br>If the molar ratio of to — Thermodynamics and Thermochemistry Chemistry Question
Question
Ethanol can undergo decomposition to form two sets of products:<br>$\text{C}_2\text{H}_5\text{OH(g)} \to \text{C}_2\text{H}_4\text{(g)} + \text{H}_2\text{O(g)}; \Delta H = +45.0\text{ kJ}$<br>$\text{C}_2\text{H}_5\text{OH(g)} \to \text{CH}_3\text{CHO(g)} + \text{H}_2\text{(g)}; \Delta H = +72.0\text{ kJ}$<br>If the molar ratio of $\text{C}_2\text{H}_4\text{(g)}$ to $\text{CH}_3\text{CHO(g)}$ in the product is 8:1, the heat absorbed in decomposition of 2.5 mole of ethanol(g) (in kJ) is
💡 Solution & Explanation
Let $8x$ moles decompose via pathway 1 and $1x$ moles via pathway 2. Total moles = $9x = 2.5 \implies x = 2.5/9$. Heat absorbed = $8x(45.0) + 1x(72.0) = 360x + 72x = 432x$. Substituting $x$: Total heat = $432 \times (2.5/9) = 48 \times 2.5 = 120\text{ kJ}$. Format as 0120.