Calculate for from the following data:<br><br><br><br> — Thermodynamics and Thermochemistry Chemistry Question
Question
Calculate $\Delta_f H$ for $\text{ZnSO}_4\text{(s)}$ from the following data:<br>$\text{ZnS(s)} \to \text{Zn(s)} + \text{S (rhombic)}, \Delta H_1 = 44\text{ kcal/mol}$<br>$2\text{ZnS(s)} + 3\text{O}_2\text{(g)} \to 2\text{ZnO(s)} + 2\text{SO}_2\text{(g)}, \Delta H_2 = -221.88\text{ kcal/mol}$<br>$2\text{SO}_2\text{(g)} + \text{O}_2\text{(g)} \to 2\text{SO}_3\text{(g)}, \Delta H_3 = -46.88\text{ kcal/mol}$<br>$\text{ZnSO}_4\text{(s)} \to \text{ZnO(s)} + \text{SO}_3\text{(g)}, \Delta H_4 = 55.1\text{ kcal/mol}$
💡 Solution & Explanation
To construct $\text{Zn(s)} + \text{S(rhombic)} + 2\text{O}_2\text{(g)} \to \text{ZnSO}_4\text{(s)}$: Reverse Eq1 (-44), add half of Eq2 (-110.94), add half of Eq3 (-23.44), and reverse Eq4 (-55.1). Sum = $-44 - 110.94 - 23.44 - 55.1 = -233.48\text{ kcal/mol}$.