---
title: "A student evaluates a reaction proposed for use in a reusable heat pack. The molar enthalpy diagram for the reaction is shown.  Which set of values is consistent with the diagram?"
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url: "https://nerd-notes.com/ubq/119402/"
date_modified: "2026-08-19T12:40:08+00:00"
---

# A student evaluates a reaction proposed for use in a reusable heat pack. The molar enthalpy diagram for the reaction is shown.

Which set of values is consistent with the diagram?

A student evaluates a reaction proposed for use in a reusable heat pack. The molar enthalpy diagram for the reaction is shown.

Which set of values is consistent with the diagram?

![Draw a grayscale reaction enthalpy graph on a white background. The vertical axis is labeled “Molar enthalpy (kJ/mol)” and has an upward arrowhead. The horizontal axis is labeled “Reaction progress” and has a rightward arrowhead. Include faint horizontal gridlines at 40, 120, and 200, with those three values marked on the vertical axis. A single solid curve begins with a horizontal segment along the middle gridline, rises smoothly to one rounded maximum touching the highest gridline, then falls smoothly to a horizontal segment along the lowest gridline. Place “Reactants” above the first plateau and “Products” above the second plateau. Include no numerical markings on the horizontal axis and no legend. No other curves, labels, text, or annotations appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1787143208-FAq427.jpg)

- **A.** \(H_{\text{reactants}}=40\ \text{kJ/mol}\), \(H_{\text{products}}=120\ \text{kJ/mol}\), and \(\Delta H=+80\ \text{kJ/mol}\)
- **B.** \(H_{\text{reactants}}=120\ \text{kJ/mol}\), \(H_{\text{products}}=40\ \text{kJ/mol}\), and \(\Delta H=-80\ \text{kJ/mol}\)
- **C.** \(H_{\text{reactants}}=120\ \text{kJ/mol}\), \(H_{\text{products}}=40\ \text{kJ/mol}\), and \(\Delta H=+80\ \text{kJ/mol}\)
- **D.** \(H_{\text{reactants}}=120\ \text{kJ/mol}\), \(H_{\text{products}}=40\ \text{kJ/mol}\), and \(\Delta H=+160\ \text{kJ/mol}\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119402/*