---
title: "A rigid, sealed \\(1.0 \\text{ L}\\) container holds an equilibrium mixture of \\(\\text{N}_2\\text{O}_4\\text{(g)}\\) and \\(\\text{NO}_2\\text{(g)}\\) at a constant temperature, as represented by the following equation.  \\[\\text{N}_2\\text{O}_4\\text{(g)} \\rightleftharpoons 2\\,\\text{NO}_2\\text{(g)}\\]  A sample of \\(\\text{Ar(g)}\\) is injected into the container at the same temperature. Which of the following best predicts and explains the effect of adding \\(\\text{Ar(g)}\\) on the equilibrium system?"
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url: "https://nerd-notes.com/ubq/119717/"
date_modified: "2026-08-21T08:12:08+00:00"
---

# A rigid, sealed \(1.0 \text{ L}\) container holds an equilibrium mixture of \(\text{N}_2\text{O}_4\text{(g)}\) and \(\text{NO}_2\text{(g)}\) at a constant temperature, as represented by the following equation.

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

A sample of \(\text{Ar(g)}\) is injected into the container at the same temperature. Which of the following best predicts and explains the effect of adding \(\text{Ar(g)}\) on the equilibrium system?

A rigid, sealed \(1.0 \text{ L}\) container holds an equilibrium mixture of \(\text{N}_2\text{O}_4\text{(g)}\) and \(\text{NO}_2\text{(g)}\) at a constant temperature, as represented by the following equation.

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

A sample of \(\text{Ar(g)}\) is injected into the container at the same temperature. Which of the following best predicts and explains the effect of adding \(\text{Ar(g)}\) on the equilibrium system?

- **A.** The system shifts toward the reactants because the increase in total pressure favors the side of the reaction with fewer moles of gas.
- **B.** The system shifts toward the products because collisions with the added argon atoms lower the activation energy for the forward reaction.
- **C.** The system does not shift because the partial pressures and molar concentrations of the reacting gases remain unchanged.
- **D.** The system does not shift because the value of the equilibrium constant changes to offset the increase in total pressure.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119717/*