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title: "A student performs a calorimetry experiment to determine the molar enthalpy of neutralization, \\(\\Delta H_{\\text{neutralization}}\\), for the reaction represented below:  \\[\\text{HCl}(aq) + \\text{NaOH}(aq) \\rightarrow \\text{NaCl}(aq) + \\text{H}_2\\text{O}(l)\\]  The student mixes \\(50.0\\text{ mL}\\) of \\(1.00\\text{ M HCl}(aq)\\) and \\(50.0\\text{ mL}\\) of \\(1.00\\text{ M NaOH}(aq)\\), both initially at \\(22.0\\text{ }^\\circ\\text{C}\\), in a polystyrene cup calorimeter. During the trial, the lid of the calorimeter is left off, allowing a significant amount of thermal energy to escape to the surrounding room before the maximum temperature is recorded. Which of the following best explains how this error affects the calculated magnitude of \\(\\Delta H_{\\text{neutralization}}\\)?"
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url: "https://nerd-notes.com/ubq/119696/"
date_modified: "2026-08-21T08:12:04+00:00"
---

# A student performs a calorimetry experiment to determine the molar enthalpy of neutralization, \(\Delta H_{\text{neutralization}}\), for the reaction represented below:

\[\text{HCl}(aq) + \text{NaOH}(aq) \rightarrow \text{NaCl}(aq) + \text{H}_2\text{O}(l)\]

The student mixes \(50.0\text{ mL}\) of \(1.00\text{ M HCl}(aq)\) and \(50.0\text{ mL}\) of \(1.00\text{ M NaOH}(aq)\), both initially at \(22.0\text{ }^\circ\text{C}\), in a polystyrene cup calorimeter. During the trial, the lid of the calorimeter is left off, allowing a significant amount of thermal energy to escape to the surrounding room before the maximum temperature is recorded. Which of the following best explains how this error affects the calculated magnitude of \(\Delta H_{\text{neutralization}}\)?

A student performs a calorimetry experiment to determine the molar enthalpy of neutralization, \(\Delta H_{\text{neutralization}}\), for the reaction represented below:

\[\text{HCl}(aq) + \text{NaOH}(aq) \rightarrow \text{NaCl}(aq) + \text{H}_2\text{O}(l)\]

The student mixes \(50.0\text{ mL}\) of \(1.00\text{ M HCl}(aq)\) and \(50.0\text{ mL}\) of \(1.00\text{ M NaOH}(aq)\), both initially at \(22.0\text{ }^\circ\text{C}\), in a polystyrene cup calorimeter. During the trial, the lid of the calorimeter is left off, allowing a significant amount of thermal energy to escape to the surrounding room before the maximum temperature is recorded. Which of the following best explains how this error affects the calculated magnitude of \(\Delta H_{\text{neutralization}}\)?

- **A.** The calculated magnitude will be too large because the heat lost to the surroundings is incorrectly assumed to increase the thermal energy transferred to the solution.
- **B.** The calculated magnitude will be too large because a lower final temperature is mistakenly assumed to reduce the denominator in \(\Delta H_{\text{neutralization}} = \dfrac{q}{n}\).
- **C.** The calculated magnitude will be too small because the observed \(\Delta T\) is lower than the true adiabatic temperature change, resulting in an underestimated value of \(q_{\text{rxn}}\).
- **D.** The calculated magnitude will be too small because the escape of thermal energy reduces the specific heat capacity, \(c\), of the aqueous mixture.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119696/*