---
title: "A reaction mixture at equilibrium is contained in a cylinder fitted with a movable piston at a constant temperature according to the following equation:  \\[ \\text{N}_2\\text{O}_4(g) \\rightleftharpoons 2\\,\\text{NO}_2(g) \\]  The volume of the container is suddenly doubled at constant temperature. Which of the following statements best predicts and justifies the response of the system as it approaches a new equilibrium?"
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url: "https://nerd-notes.com/ubq/119771/"
date_modified: "2026-08-21T08:12:17+00:00"
---

# A reaction mixture at equilibrium is contained in a cylinder fitted with a movable piston at a constant temperature according to the following equation:

\[ \text{N}_2\text{O}_4(g) \rightleftharpoons 2\,\text{NO}_2(g) \]

The volume of the container is suddenly doubled at constant temperature. Which of the following statements best predicts and justifies the response of the system as it approaches a new equilibrium?

A reaction mixture at equilibrium is contained in a cylinder fitted with a movable piston at a constant temperature according to the following equation:

\[ \text{N}_2\text{O}_4(g) \rightleftharpoons 2\,\text{NO}_2(g) \]

The volume of the container is suddenly doubled at constant temperature. Which of the following statements best predicts and justifies the response of the system as it approaches a new equilibrium?

- **A.** The reaction shifts toward the reactants because diluting the gas mixture decreases the value of the equilibrium constant, \(K_c\), causing \(Q_c > K_c\).
- **B.** The reaction shifts toward the reactants because the concentration of \(\text{N}_2\text{O}_4(g)\) in the denominator decreases by a greater factor than the numerator, causing \(Q_c > K_c\).
- **C.** The reaction shifts toward the products because decreasing the total pressure increases the value of the equilibrium constant, \(K_c\), causing \(Q_c < K_c\).
- **D.** The reaction shifts toward the products because halving the concentrations decreases the numerator of \(Q_c\) by a factor of \(4\) while the denominator decreases by a factor of \(2\), causing \(Q_c < K_c\).

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119771/*