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title: "A student adds \\(8.00\\text{ g}\\) of solid ammonium nitrate, \\(\\text{NH}_4\\text{NO}_3\\) (molar mass \\(80.0\\text{ g/mol}\\)), to \\(92.0\\text{ g}\\) of distilled water at \\(25.0^\\circ\\text{C}\\) inside an insulated coffee-cup calorimeter. The solid dissolves completely according to the equation below, and the temperature of the resulting solution decreases to a minimum of \\(19.0^\\circ\\text{C}\\).  \\[ \\text{NH}_4\\text{NO}_3\\text{(s)} \\rightarrow \\text{NH}_4^+\\text{(aq)} + \\text{NO}_3^-\\text{(aq)} \\]  Assuming the solution has a specific heat capacity of \\(4.18\\text{ J}/(\\text{g}\\cdot^\\circ\\text{C})\\) and that heat transfer with the calorimeter walls and surroundings is negligible, what is the experimental molar enthalpy of solution, \\(\\Delta H_{\\text{soln}}\\), for \\(\\text{NH}_4\\text{NO}_3\\)?"
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url: "https://nerd-notes.com/ubq/121394/"
date_modified: "2026-08-23T05:02:04+00:00"
---

# A student adds \(8.00\text{ g}\) of solid ammonium nitrate, \(\text{NH}_4\text{NO}_3\) (molar mass \(80.0\text{ g/mol}\)), to \(92.0\text{ g}\) of distilled water at \(25.0^\circ\text{C}\) inside an insulated coffee-cup calorimeter. The solid dissolves completely according to the equation below, and the temperature of the resulting solution decreases to a minimum of \(19.0^\circ\text{C}\).

\[ \text{NH}_4\text{NO}_3\text{(s)} \rightarrow \text{NH}_4^+\text{(aq)} + \text{NO}_3^-\text{(aq)} \]

Assuming the solution has a specific heat capacity of \(4.18\text{ J}/(\text{g}\cdot^\circ\text{C})\) and that heat transfer with the calorimeter walls and surroundings is negligible, what is the experimental molar enthalpy of solution, \(\Delta H_{\text{soln}}\), for \(\text{NH}_4\text{NO}_3\)?

A student adds \(8.00\text{ g}\) of solid ammonium nitrate, \(\text{NH}_4\text{NO}_3\) (molar mass \(80.0\text{ g/mol}\)), to \(92.0\text{ g}\) of distilled water at \(25.0^\circ\text{C}\) inside an insulated coffee-cup calorimeter. The solid dissolves completely according to the equation below, and the temperature of the resulting solution decreases to a minimum of \(19.0^\circ\text{C}\).

\[ \text{NH}_4\text{NO}_3\text{(s)} \rightarrow \text{NH}_4^+\text{(aq)} + \text{NO}_3^-\text{(aq)} \]

Assuming the solution has a specific heat capacity of \(4.18\text{ J}/(\text{g}\cdot^\circ\text{C})\) and that heat transfer with the calorimeter walls and surroundings is negligible, what is the experimental molar enthalpy of solution, \(\Delta H_{\text{soln}}\), for \(\text{NH}_4\text{NO}_3\)?

- **A.** \(-25.1\text{ kJ/mol}_{\text{rxn}}\)
- **B.** \(-2.51\text{ kJ/mol}_{\text{rxn}}\)
- **C.** \(+2.51\text{ kJ/mol}_{\text{rxn}}\)
- **D.** \(+25.1\text{ kJ/mol}_{\text{rxn}}\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/121394/*