---
title: "A student investigating a gas-phase catalytic process for converting sulfur dioxide to sulfur trioxide proposes the following elementary steps.  Step 1 (fast): \\(2\\text{NO}\\text{(g)} \\rightleftharpoons \\text{N}_2\\text{O}_2\\text{(g)}\\)  Step 2 (slow): \\(\\text{N}_2\\text{O}_2\\text{(g)}+\\text{O}_2\\text{(g)} \\rightarrow 2\\text{NO}_2\\text{(g)}\\)  Step 3 (fast): \\(\\text{NO}_2\\text{(g)}+\\text{SO}_2\\text{(g)} \\rightarrow \\text{NO}\\text{(g)}+\\text{SO}_3\\text{(g)}\\)  Which choice correctly identifies the catalyst and all the reaction intermediates in the proposed mechanism?"
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date_modified: "2026-08-19T12:41:38+00:00"
---

# A student investigating a gas-phase catalytic process for converting sulfur dioxide to sulfur trioxide proposes the following elementary steps.

Step 1 (fast): \(2\text{NO}\text{(g)} \rightleftharpoons \text{N}_2\text{O}_2\text{(g)}\)

Step 2 (slow): \(\text{N}_2\text{O}_2\text{(g)}+\text{O}_2\text{(g)} \rightarrow 2\text{NO}_2\text{(g)}\)

Step 3 (fast): \(\text{NO}_2\text{(g)}+\text{SO}_2\text{(g)} \rightarrow \text{NO}\text{(g)}+\text{SO}_3\text{(g)}\)

Which choice correctly identifies the catalyst and all the reaction intermediates in the proposed mechanism?

A student investigating a gas-phase catalytic process for converting sulfur dioxide to sulfur trioxide proposes the following elementary steps.

Step 1 (fast): \(2\text{NO}\text{(g)} \rightleftharpoons \text{N}_2\text{O}_2\text{(g)}\)

Step 2 (slow): \(\text{N}_2\text{O}_2\text{(g)}+\text{O}_2\text{(g)} \rightarrow 2\text{NO}_2\text{(g)}\)

Step 3 (fast): \(\text{NO}_2\text{(g)}+\text{SO}_2\text{(g)} \rightarrow \text{NO}\text{(g)}+\text{SO}_3\text{(g)}\)

Which choice correctly identifies the catalyst and all the reaction intermediates in the proposed mechanism?

- **A.** Catalyst: \(\text{N}_2\text{O}_2\text{(g)}\); intermediates: \(\text{NO}\text{(g)}\) and \(\text{NO}_2\text{(g)}\)
- **B.** Catalyst: \(\text{NO}\text{(g)}\); intermediates: \(\text{N}_2\text{O}_2\text{(g)}\) and \(\text{NO}_2\text{(g)}\)
- **C.** Catalyst: \(\text{O}_2\text{(g)}\); intermediates: \(\text{N}_2\text{O}_2\text{(g)}\) and \(\text{NO}_2\text{(g)}\)
- **D.** Catalyst: \(\text{NO}\text{(g)}\); intermediates: \(\text{N}_2\text{O}_2\text{(g)}\) and \(\text{SO}_3\text{(g)}\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119530/*