---
title: "A student investigates the reaction between gaseous nitrogen monoxide and oxygen to form nitrogen dioxide, represented by the balanced equation below.  \\[ 2\\,\\text{NO(g)} + \\text{O}_2\\text{(g)} \\rightarrow 2\\,\\text{NO}_2\\text{(g)} \\]  The student constructs particulate representations for the initial and final states of four different trials conducted in separate rigid \\(1.0\\text{ L}\\) containers. The particle counts recorded from the student’s representations are summarized in the table below.  | Trial | Initial \\(\\text{NO}\\) particles | Initial \\(\\text{O}_2\\) particles | Final \\(\\text{NO}\\) particles | Final \\(\\text{O}_2\\) particles | Final \\(\\text{NO}_2\\) particles | | :—: | :—: | :—: | :—: | :—: | :—: | | 1 | \\(6\\) | \\(2\\) | \\(0\\) | \\(0\\) | \\(4\\) | | 2 | \\(4\\) | \\(4\\) | \\(0\\) | \\(2\\) | \\(2\\) | | 3 | \\(6\\) | \\(4\\) | \\(2\\) | \\(1\\) | \\(4\\) | | 4 | \\(8\\) | \\(3\\) | \\(2\\) | \\(0\\) | \\(6\\) |  Assuming each reaction proceeds to completion, which trial’s particulate model correctly represents the final mixture while obeying the law of conservation of mass?"
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url: "https://nerd-notes.com/ubq/123701/"
date_modified: "2026-09-28T12:02:02+00:00"
---

# A student investigates the reaction between gaseous nitrogen monoxide and oxygen to form nitrogen dioxide, represented by the balanced equation below.

\[ 2\,\text{NO(g)} + \text{O}_2\text{(g)} \rightarrow 2\,\text{NO}_2\text{(g)} \]

The student constructs particulate representations for the initial and final states of four different trials conducted in separate rigid \(1.0\text{ L}\) containers. The particle counts recorded from the student’s representations are summarized in the table below.

| Trial | Initial \(\text{NO}\) particles | Initial \(\text{O}_2\) particles | Final \(\text{NO}\) particles | Final \(\text{O}_2\) particles | Final \(\text{NO}_2\) particles |
| :—: | :—: | :—: | :—: | :—: | :—: |
| 1 | \(6\) | \(2\) | \(0\) | \(0\) | \(4\) |
| 2 | \(4\) | \(4\) | \(0\) | \(2\) | \(2\) |
| 3 | \(6\) | \(4\) | \(2\) | \(1\) | \(4\) |
| 4 | \(8\) | \(3\) | \(2\) | \(0\) | \(6\) |

Assuming each reaction proceeds to completion, which trial’s particulate model correctly represents the final mixture while obeying the law of conservation of mass?

A student investigates the reaction between gaseous nitrogen monoxide and oxygen to form nitrogen dioxide, represented by the balanced equation below.

\[ 2\,\text{NO(g)} + \text{O}_2\text{(g)} \rightarrow 2\,\text{NO}_2\text{(g)} \]

The student constructs particulate representations for the initial and final states of four different trials conducted in separate rigid \(1.0\text{ L}\) containers. The particle counts recorded from the student's representations are summarized in the table below.

| Trial | Initial \(\text{NO}\) particles | Initial \(\text{O}_2\) particles | Final \(\text{NO}\) particles | Final \(\text{O}_2\) particles | Final \(\text{NO}_2\) particles |
| :---: | :---: | :---: | :---: | :---: | :---: |
| 1 | \(6\) | \(2\) | \(0\) | \(0\) | \(4\) |
| 2 | \(4\) | \(4\) | \(0\) | \(2\) | \(2\) |
| 3 | \(6\) | \(4\) | \(2\) | \(1\) | \(4\) |
| 4 | \(8\) | \(3\) | \(2\) | \(0\) | \(6\) |

Assuming each reaction proceeds to completion, which trial's particulate model correctly represents the final mixture while obeying the law of conservation of mass?

- **A.** Trial \(1\), because all initial reactant particles are completely consumed, resulting in zero unreacted \(\text{NO}\) or \(\text{O}_2\) molecules in the final mixture.
- **B.** Trial \(2\), because the ratio of remaining \(\text{O}_2\) molecules to produced \(\text{NO}_2\) molecules matches the \(1:1\) stoichiometric ratio in the balanced chemical equation.
- **C.** Trial \(3\), because unreacted \(\text{NO}\) and \(\text{O}_2\) are both present to ensure that the total count of nitrogen atoms remains constant.
- **D.** Trial \(4\), because the limiting reactant is completely consumed, leaving \(2\) unreacted \(\text{NO}\) molecules and forming \(6\) \(\text{NO}_2\) molecules while conserving both nitrogen and oxygen atoms.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123701/*