---
title: "A student investigates the gas-phase synthesis of phosgene according to the following balanced equation:  \\[ \\text{CO}(g) + \\text{Cl}_2(g) \\rightleftharpoons \\text{COCl}_2(g) \\]  At \\(500 \\text{ K}\\), the equilibrium constant \\(K_c\\) for the reaction is \\(5.0\\). The student measures the initial concentrations of the gases in a rigid container at \\(500 \\text{ K}\\) and records the data in the table below.  | Species | Initial concentration (M) | |—|—| | \\(\\text{CO}(g)\\) | \\(0.10\\) | | \\(\\text{Cl}_2(g)\\) | \\(0.20\\) | | \\(\\text{COCl}_2(g)\\) | \\(0.30\\) |  Which of the following correctly compares the reaction quotient, \\(Q_c\\), to \\(K_c\\) and describes the relative rates of the forward and reverse reactions immediately after mixing?"
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/119278/"
date_modified: "2026-08-19T12:39:37+00:00"
---

# A student investigates the gas-phase synthesis of phosgene according to the following balanced equation:

\[ \text{CO}(g) + \text{Cl}_2(g) \rightleftharpoons \text{COCl}_2(g) \]

At \(500 \text{ K}\), the equilibrium constant \(K_c\) for the reaction is \(5.0\). The student measures the initial concentrations of the gases in a rigid container at \(500 \text{ K}\) and records the data in the table below.

| Species | Initial concentration (M) |
|—|—|
| \(\text{CO}(g)\) | \(0.10\) |
| \(\text{Cl}_2(g)\) | \(0.20\) |
| \(\text{COCl}_2(g)\) | \(0.30\) |

Which of the following correctly compares the reaction quotient, \(Q_c\), to \(K_c\) and describes the relative rates of the forward and reverse reactions immediately after mixing?

A student investigates the gas-phase synthesis of phosgene according to the following balanced equation:

\[ \text{CO}(g) + \text{Cl}_2(g) \rightleftharpoons \text{COCl}_2(g) \]

At \(500 \text{ K}\), the equilibrium constant \(K_c\) for the reaction is \(5.0\). The student measures the initial concentrations of the gases in a rigid container at \(500 \text{ K}\) and records the data in the table below.

| Species | Initial concentration (M) |
|---|---|
| \(\text{CO}(g)\) | \(0.10\) |
| \(\text{Cl}_2(g)\) | \(0.20\) |
| \(\text{COCl}_2(g)\) | \(0.30\) |

Which of the following correctly compares the reaction quotient, \(Q_c\), to \(K_c\) and describes the relative rates of the forward and reverse reactions immediately after mixing?

- **A.** \(Q_c = 0.067\); because \(Q_c < K_c\), the rate of the forward reaction is greater than the rate of the reverse reaction.
- **B.** \(Q_c = 15\); because \(Q_c > K_c\), the rate of the forward reaction is greater than the rate of the reverse reaction.
- **C.** \(Q_c = 15\); because \(Q_c > K_c\), the rate of the reverse reaction is greater than the rate of the forward reaction.
- **D.** \(Q_c = 1.5\); because \(Q_c < K_c\), the rate of the forward reaction is greater than the rate of the reverse reaction.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119278/*