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title: "A proposed two-step mechanism for the decomposition of hydrogen peroxide, \\(\\text{H}_2\\text{O}_2\\text{(aq)}\\), in the presence of iodide ions is shown below:  \\[ \\text{Step 1: } \\text{H}_2\\text{O}_2\\text{(aq)} + \\text{I}^-\\text{(aq)} \\rightarrow \\text{IO}^-\\text{(aq)} + \\text{H}_2\\text{O(l)} \\quad (\\text{slow}) \\] \\[ \\text{Step 2: } \\text{H}_2\\text{O}_2\\text{(aq)} + \\text{IO}^-\\text{(aq)} \\rightarrow \\text{I}^-\\text{(aq)} + \\text{H}_2\\text{O(l)} + \\text{O}_2\\text{(g)} \\quad (\\text{fast}) \\]  Which of the following correctly identifies the role of \\(\\text{IO}^-\\text{(aq)}\\) in this mechanism and gives the rate law for the rate-determining elementary step?"
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url: "https://nerd-notes.com/ubq/119963/"
date_modified: "2026-08-21T08:31:11+00:00"
---

# A proposed two-step mechanism for the decomposition of hydrogen peroxide, \(\text{H}_2\text{O}_2\text{(aq)}\), in the presence of iodide ions is shown below:

\[ \text{Step 1: } \text{H}_2\text{O}_2\text{(aq)} + \text{I}^-\text{(aq)} \rightarrow \text{IO}^-\text{(aq)} + \text{H}_2\text{O(l)} \quad (\text{slow}) \]
\[ \text{Step 2: } \text{H}_2\text{O}_2\text{(aq)} + \text{IO}^-\text{(aq)} \rightarrow \text{I}^-\text{(aq)} + \text{H}_2\text{O(l)} + \text{O}_2\text{(g)} \quad (\text{fast}) \]

Which of the following correctly identifies the role of \(\text{IO}^-\text{(aq)}\) in this mechanism and gives the rate law for the rate-determining elementary step?

A proposed two-step mechanism for the decomposition of hydrogen peroxide, \(\text{H}_2\text{O}_2\text{(aq)}\), in the presence of iodide ions is shown below:

\[ \text{Step 1: } \text{H}_2\text{O}_2\text{(aq)} + \text{I}^-\text{(aq)} \rightarrow \text{IO}^-\text{(aq)} + \text{H}_2\text{O(l)} \quad (\text{slow}) \]
\[ \text{Step 2: } \text{H}_2\text{O}_2\text{(aq)} + \text{IO}^-\text{(aq)} \rightarrow \text{I}^-\text{(aq)} + \text{H}_2\text{O(l)} + \text{O}_2\text{(g)} \quad (\text{fast}) \]

Which of the following correctly identifies the role of \(\text{IO}^-\text{(aq)}\) in this mechanism and gives the rate law for the rate-determining elementary step?

- **A.** \(\text{IO}^-\text{(aq)}\) is a catalyst, and the rate law for Step 1 is \(\text{Rate} = k[\text{H}_2\text{O}_2][\text{I}^-]\).
- **B.** \(\text{IO}^-\text{(aq)}\) is an intermediate, and the rate law for Step 1 is \(\text{Rate} = k[\text{H}_2\text{O}_2][\text{I}^-]\).
- **C.** \(\text{IO}^-\text{(aq)}\) is an intermediate, and the rate law for Step 1 is \(\text{Rate} = k[\text{H}_2\text{O}_2]\).
- **D.** \(\text{IO}^-\text{(aq)}\) is a catalyst, and the rate law for Step 1 is \(\text{Rate} = k[\text{H}_2\text{O}_2]\).

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119963/*