---
title: "The reaction energy profile for the uncatalyzed oxidation of sulfur dioxide is shown in the diagram.  \\[ 2\\,\\text{SO}_2\\text{(g)} + \\text{O}_2\\text{(g)} \\rightarrow 2\\,\\text{SO}_3\\text{(g)} \\quad \\Delta H^\\circ_{\\text{rxn}} = -198\\text{ kJ/mol}_{\\text{rxn}} \\]  A suitable solid catalyst is added to the system, providing an alternate mechanism with a lower activation energy. Which of the following best predicts the changes to the activation energy, \\(E_a\\), and the standard enthalpy of reaction, \\(\\Delta H^\\circ_{\\text{rxn}}\\), for the catalyzed reaction compared to the uncatalyzed reaction?"
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url: "https://nerd-notes.com/ubq/123754/"
date_modified: "2026-09-28T12:29:26+00:00"
---

# The reaction energy profile for the uncatalyzed oxidation of sulfur dioxide is shown in the diagram.

\[ 2\,\text{SO}_2\text{(g)} + \text{O}_2\text{(g)} \rightarrow 2\,\text{SO}_3\text{(g)} \quad \Delta H^\circ_{\text{rxn}} = -198\text{ kJ/mol}_{\text{rxn}} \]

A suitable solid catalyst is added to the system, providing an alternate mechanism with a lower activation energy. Which of the following best predicts the changes to the activation energy, \(E_a\), and the standard enthalpy of reaction, \(\Delta H^\circ_{\text{rxn}}\), for the catalyzed reaction compared to the uncatalyzed reaction?

The reaction energy profile for the uncatalyzed oxidation of sulfur dioxide is shown in the diagram.

\[ 2\,\text{SO}_2\text{(g)} + \text{O}_2\text{(g)} \rightarrow 2\,\text{SO}_3\text{(g)} \quad \Delta H^\circ_{\text{rxn}} = -198\text{ kJ/mol}_{\text{rxn}} \]

A suitable solid catalyst is added to the system, providing an alternate mechanism with a lower activation energy. Which of the following best predicts the changes to the activation energy, \(E_a\), and the standard enthalpy of reaction, \(\Delta H^\circ_{\text{rxn}}\), for the catalyzed reaction compared to the uncatalyzed reaction?

![A grayscale reaction energy profile with bare axes and no gridlines. The vertical axis is labeled 'Potential Energy' and the horizontal axis is labeled 'Reaction Coordinate'. A single solid black curve begins on the left at a flat plateau representing reactants labeled '2 SO2(g) + O2(g)'. The curve rises to a single smooth peak representing the transition state, and then falls to a lower horizontal plateau on the right representing products labeled '2 SO3(g)'. A vertical double-headed arrow between the reactant plateau and the peak is labeled 'Ea'. A vertical double-headed arrow between the reactant plateau and the product plateau is labeled 'Delta H rxn'. No other curves, gridlines, colors, or decorative annotations appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1790598566-5U9HG0.jpg)

- **A.** \(E_a\) decreases, and \(\Delta H^\circ_{\text{rxn}}\) becomes more negative because the catalyst releases additional thermal energy.
- **B.** \(E_a\) remains unchanged, and \(\Delta H^\circ_{\text{rxn}}\) becomes more negative because the catalyst lowers the potential energy of the products.
- **C.** \(E_a\) decreases, and \(\Delta H^\circ_{\text{rxn}}\) becomes less negative because the lower peak shortens the vertical distance to the products.
- **D.** \(E_a\) decreases, and \(\Delta H^\circ_{\text{rxn}}\) remains unchanged because the catalyst alters the transition state without changing the potential energy of the reactants or products.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123754/*