Calculate for aqueous chloride ion from the following data:<br><br><br> — Thermodynamics and Thermochemistry Chemistry Question
Question
Calculate $\Delta_f H^\circ$ for aqueous chloride ion from the following data:<br>$1/2 \text{H}_2\text{(g)} + 1/2 \text{Cl}_2\text{(g)} \to \text{HCl(g)}, \Delta_f H^\circ = -92.4\text{ kJ}$<br>$\text{HCl(g)} + n\text{H}_2\text{O(l)} \to \text{H}^+\text{(aq)} + \text{Cl}^-\text{(aq)}, \Delta H^\circ = -74.8\text{ kJ}$<br>$\Delta_f H^\circ(\text{H}^+, \text{aq.}) = 0.0\text{ kJ}$
Answer: D
💡 Solution & Explanation
The overall formation reaction for aqueous ions is the sum of formation of the gas and its dissolution. $\Delta_f H^\circ(\text{Cl}^-) = \Delta_f H^\circ(\text{HCl, g}) + \Delta H_{\text{sol}}(\text{HCl, g}) = -92.4 + (-74.8) = -167.2\text{ kJ/mol}$ (since $\Delta_f H^\circ(\text{H}^+) = 0$).
💬Ask on WhatsApp →
Still have doubts about this question?
Send it to our AI chemistry tutor on WhatsApp — gets answered in minutes