---
title: "A student investigates the dissolution of a sparingly soluble salt, \\(\\text{PbI}_2\\text{(s)}\\), in pure water at three different temperatures. The experimental data collected are shown in the table below.  | Temperature (\\(\\text{K}\\)) | Molar Solubility (\\(\\text{mol}\\cdot\\text{L}^{-1}\\)) | | :—: | :—: | | \\(283\\) | \\(1.2 \\times 10^{-3}\\) | | \\(298\\) | \\(1.7 \\times 10^{-3}\\) | | \\(313\\) | \\(2.5 \\times 10^{-3}\\) |  The dissolution equilibrium is represented by the following equation: \\[ \\text{PbI}_2(s) \\rightleftharpoons \\text{Pb}^{2+}(aq) + 2\\,\\text{I}^-(aq) \\]  Which of the following claims about the standard enthalpy of dissolution, \\(\\Delta H^\\circ_{\\text{soln}}\\), is best supported by the data?"
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url: "https://nerd-notes.com/ubq/123789/"
date_modified: "2026-09-28T12:30:18+00:00"
---

# A student investigates the dissolution of a sparingly soluble salt, \(\text{PbI}_2\text{(s)}\), in pure water at three different temperatures. The experimental data collected are shown in the table below.

| Temperature (\(\text{K}\)) | Molar Solubility (\(\text{mol}\cdot\text{L}^{-1}\)) |
| :—: | :—: |
| \(283\) | \(1.2 \times 10^{-3}\) |
| \(298\) | \(1.7 \times 10^{-3}\) |
| \(313\) | \(2.5 \times 10^{-3}\) |

The dissolution equilibrium is represented by the following equation:
\[ \text{PbI}_2(s) \rightleftharpoons \text{Pb}^{2+}(aq) + 2\,\text{I}^-(aq) \]

Which of the following claims about the standard enthalpy of dissolution, \(\Delta H^\circ_{\text{soln}}\), is best supported by the data?

A student investigates the dissolution of a sparingly soluble salt, \(\text{PbI}_2\text{(s)}\), in pure water at three different temperatures. The experimental data collected are shown in the table below.

| Temperature (\(\text{K}\)) | Molar Solubility (\(\text{mol}\cdot\text{L}^{-1}\)) |
| :---: | :---: |
| \(283\) | \(1.2 \times 10^{-3}\) |
| \(298\) | \(1.7 \times 10^{-3}\) |
| \(313\) | \(2.5 \times 10^{-3}\) |

The dissolution equilibrium is represented by the following equation:
\[ \text{PbI}_2(s) \rightleftharpoons \text{Pb}^{2+}(aq) + 2\,\text{I}^-(aq) \]

Which of the following claims about the standard enthalpy of dissolution, \(\Delta H^\circ_{\text{soln}}\), is best supported by the data?

- **A.** \(\Delta H^\circ_{\text{soln}} < 0\), because the higher temperature provides the activation energy necessary to break the ionic bonds in the solid lattice.
- **B.** \(\Delta H^\circ_{\text{soln}} < 0\), because the increase in entropy during dissolution causes the system to release heat as temperature increases.
- **C.** \(\Delta H^\circ_{\text{soln}} > 0\), because the molar solubility increases with temperature, indicating that heat acts as a reactant in shifting the equilibrium toward dissolved ions.
- **D.** \(\Delta H^\circ_{\text{soln}} > 0\), because more solid dissolves at higher temperatures in order to decrease the value of \(K_{sp}\) and restore equilibrium.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123789/*