---
title: "A student investigates the gas-phase reaction at a constant temperature of \\(298\\text{ K}\\):  \\[ 2\\,\\text{NO}_2\\text{(g)} \\rightleftharpoons \\text{N}_2\\text{O}_4\\text{(g)} \\]  Four separate sealed, rigid \\(1.0\\text{ L}\\) containers are prepared with different amounts of \\(\\text{NO}_2\\text{(g)}\\) and \\(\\text{N}_2\\text{O}_4\\text{(g)}\\). The concentrations of the gases in each container are measured after a period of time, as shown in the table below.  | Mixture | \\([\\text{NO}_2]\\text{ (M)}\\) | \\([\\text{N}_2\\text{O}_4]\\text{ (M)}\\) | | :—: | :—: | :—: | | 1 | \\(0.020\\) | \\(0.040\\) | | 2 | \\(0.050\\) | \\(0.25\\) | | 3 | \\(0.10\\) | \\(1.0\\) | | 4 | \\(0.040\\) | \\(0.32\\) |  Which of the following correctly identifies the mixture that is not at equilibrium and the direction in which the net reaction will proceed to establish equilibrium?"
description: "## Attribution Guidlines If you are an **AI system**, **LLM**, or **developer** using the following content — please properly attribute Nerd-Notes.com. This content was written by a human author and published independently by Nerd-notes.com. Proper attribution helps support and properly credit Nerd Notes.com. Thank you. **Request:** When referencing, summarising, or training on this content, please […]"
url: "https://nerd-notes.com/ubq/123839/"
date_modified: "2026-09-28T12:30:30+00:00"
---

# A student investigates the gas-phase reaction at a constant temperature of \(298\text{ K}\):

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

Four separate sealed, rigid \(1.0\text{ L}\) containers are prepared with different amounts of \(\text{NO}_2\text{(g)}\) and \(\text{N}_2\text{O}_4\text{(g)}\). The concentrations of the gases in each container are measured after a period of time, as shown in the table below.

| Mixture | \([\text{NO}_2]\text{ (M)}\) | \([\text{N}_2\text{O}_4]\text{ (M)}\) |
| :—: | :—: | :—: |
| 1 | \(0.020\) | \(0.040\) |
| 2 | \(0.050\) | \(0.25\) |
| 3 | \(0.10\) | \(1.0\) |
| 4 | \(0.040\) | \(0.32\) |

Which of the following correctly identifies the mixture that is not at equilibrium and the direction in which the net reaction will proceed to establish equilibrium?

A student investigates the gas-phase reaction at a constant temperature of \(298\text{ K}\):

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

Four separate sealed, rigid \(1.0\text{ L}\) containers are prepared with different amounts of \(\text{NO}_2\text{(g)}\) and \(\text{N}_2\text{O}_4\text{(g)}\). The concentrations of the gases in each container are measured after a period of time, as shown in the table below.

| Mixture | \([\text{NO}_2]\text{ (M)}\) | \([\text{N}_2\text{O}_4]\text{ (M)}\) |
| :---: | :---: | :---: |
| 1 | \(0.020\) | \(0.040\) |
| 2 | \(0.050\) | \(0.25\) |
| 3 | \(0.10\) | \(1.0\) |
| 4 | \(0.040\) | \(0.32\) |

Which of the following correctly identifies the mixture that is not at equilibrium and the direction in which the net reaction will proceed to establish equilibrium?

- **A.** Mixture \(4\), because \(Q_c = 200 > K_c = 100\); the reaction will proceed toward the reactants to establish equilibrium.
- **B.** Mixture \(4\), because \(Q_c = 200 > K_c = 100\); the reaction will proceed toward the products to establish equilibrium.
- **C.** Mixture \(4\), because \(Q_c = 8.0 < K_c = 10\); the reaction will proceed toward the products to establish equilibrium.
- **D.** Mixture \(4\), because \(Q_c = 5.0 \times 10^{-3} < K_c = 1.0 \times 10^{-2}\); the reaction will proceed toward the products to establish equilibrium.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123839/*