---
title: "A sample of propane gas, \\(\\text{C}_3\\text{H}_8\\text{(g)}\\), is mixed with excess oxygen gas, \\(\\text{O}_2\\text{(g)}\\), in a sealed, rigid container at \\(298\\text{ K}\\). The combustion reaction is represented by the equation below.  \\[ \\text{C}_3\\text{H}_8\\text{(g)} + 5\\,\\text{O}_2\\text{(g)} \\rightarrow 3\\,\\text{CO}_2\\text{(g)} + 4\\,\\text{H}_2\\text{O(g)} \\quad \\Delta G^\\circ_{298} = -2074\\text{ kJ/mol}_{rxn} \\]  Although the reaction is thermodynamically favorable at \\(298\\text{ K}\\), no formation of products is detected after several days. When a small piece of platinum mesh is introduced into the container, the reaction proceeds rapidly. Which of the following best explains why the uncatalyzed mixture does not react at a measurable rate and describes the role of the platinum catalyst?"
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/123919/"
date_modified: "2026-09-28T12:32:11+00:00"
---

# A sample of propane gas, \(\text{C}_3\text{H}_8\text{(g)}\), is mixed with excess oxygen gas, \(\text{O}_2\text{(g)}\), in a sealed, rigid container at \(298\text{ K}\). The combustion reaction is represented by the equation below.

\[ \text{C}_3\text{H}_8\text{(g)} + 5\,\text{O}_2\text{(g)} \rightarrow 3\,\text{CO}_2\text{(g)} + 4\,\text{H}_2\text{O(g)} \quad \Delta G^\circ_{298} = -2074\text{ kJ/mol}_{rxn} \]

Although the reaction is thermodynamically favorable at \(298\text{ K}\), no formation of products is detected after several days. When a small piece of platinum mesh is introduced into the container, the reaction proceeds rapidly. Which of the following best explains why the uncatalyzed mixture does not react at a measurable rate and describes the role of the platinum catalyst?

A sample of propane gas, \(\text{C}_3\text{H}_8\text{(g)}\), is mixed with excess oxygen gas, \(\text{O}_2\text{(g)}\), in a sealed, rigid container at \(298\text{ K}\). The combustion reaction is represented by the equation below.

\[ \text{C}_3\text{H}_8\text{(g)} + 5\,\text{O}_2\text{(g)} \rightarrow 3\,\text{CO}_2\text{(g)} + 4\,\text{H}_2\text{O(g)} \quad \Delta G^\circ_{298} = -2074\text{ kJ/mol}_{rxn} \]

Although the reaction is thermodynamically favorable at \(298\text{ K}\), no formation of products is detected after several days. When a small piece of platinum mesh is introduced into the container, the reaction proceeds rapidly. Which of the following best explains why the uncatalyzed mixture does not react at a measurable rate and describes the role of the platinum catalyst?

- **A.** The uncatalyzed reaction is under thermodynamic control because \(\Delta G^\circ < 0\), and the catalyst increases the reaction rate by making \(\Delta G^\circ\) more negative.
- **B.** The uncatalyzed reaction is under thermodynamic control because the system is at equilibrium with \(K < 1\), and the catalyst shifts the reaction toward products by increasing the equilibrium constant \(K\).
- **C.** The uncatalyzed reaction is under kinetic control because a high activation energy prevents it from proceeding at a measurable rate, and the catalyst provides an alternative reaction pathway with a lower activation energy without altering \(\Delta G^\circ\).
- **D.** The uncatalyzed reaction is under kinetic control because a high activation energy prevents it from proceeding at a measurable rate, and the catalyst increases the reaction rate by increasing the average kinetic energy of the reactant molecules.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123919/*