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title: "A student measures the equilibrium concentration of hydronium ion in a \\(0.10 \\text{ M}\\) aqueous solution of a weak monoprotic acid, \\(\\text{HA(aq)}\\), at \\(298 \\text{ K}\\).  \\[ \\text{HA(aq)} + \\text{H}_2\\text{O(l)} \\rightleftharpoons \\text{H}_3\\text{O}^+\\text{(aq)} + \\text{A}^-\\text{(aq)} \\]  At equilibrium, \\([\\text{H}_3\\text{O}^+] = 1.0 \\times 10^{-3} \\text{ M}\\).  Useful information at \\(298 \\text{ K}\\): – \\(RT \\approx 2.48 \\text{ kJ/mol}\\) – \\(\\ln(1.0 \\times 10^{-6}) \\approx -13.8\\) – \\(\\ln(1.0 \\times 10^{-5}) \\approx -11.5\\) – \\(\\ln(1.0 \\times 10^{-3}) \\approx -6.9\\)  Based on these data, what is the value of \\(\\Delta G^\\circ\\) for the ionization of \\(\\text{HA(aq)}\\) at \\(298 \\text{ K}\\)?"
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date_modified: "2026-08-23T04:23:11+00:00"
---

# A student measures the equilibrium concentration of hydronium ion in a \(0.10 \text{ M}\) aqueous solution of a weak monoprotic acid, \(\text{HA(aq)}\), at \(298 \text{ K}\).

\[ \text{HA(aq)} + \text{H}_2\text{O(l)} \rightleftharpoons \text{H}_3\text{O}^+\text{(aq)} + \text{A}^-\text{(aq)} \]

At equilibrium, \([\text{H}_3\text{O}^+] = 1.0 \times 10^{-3} \text{ M}\).

Useful information at \(298 \text{ K}\):
– \(RT \approx 2.48 \text{ kJ/mol}\)
– \(\ln(1.0 \times 10^{-6}) \approx -13.8\)
– \(\ln(1.0 \times 10^{-5}) \approx -11.5\)
– \(\ln(1.0 \times 10^{-3}) \approx -6.9\)

Based on these data, what is the value of \(\Delta G^\circ\) for the ionization of \(\text{HA(aq)}\) at \(298 \text{ K}\)?

A student measures the equilibrium concentration of hydronium ion in a \(0.10 \text{ M}\) aqueous solution of a weak monoprotic acid, \(\text{HA(aq)}\), at \(298 \text{ K}\).

\[ \text{HA(aq)} + \text{H}_2\text{O(l)} \rightleftharpoons \text{H}_3\text{O}^+\text{(aq)} + \text{A}^-\text{(aq)} \]

At equilibrium, \([\text{H}_3\text{O}^+] = 1.0 \times 10^{-3} \text{ M}\).

Useful information at \(298 \text{ K}\):
- \(RT \approx 2.48 \text{ kJ/mol}\)
- \(\ln(1.0 \times 10^{-6}) \approx -13.8\)
- \(\ln(1.0 \times 10^{-5}) \approx -11.5\)
- \(\ln(1.0 \times 10^{-3}) \approx -6.9\)

Based on these data, what is the value of \(\Delta G^\circ\) for the ionization of \(\text{HA(aq)}\) at \(298 \text{ K}\)?

- **A.** \(-29 \text{ kJ/mol}\)
- **B.** \(+17 \text{ kJ/mol}\)
- **C.** \(+29 \text{ kJ/mol}\)
- **D.** \(+34 \text{ kJ/mol}\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/120334/*