---
title: "A proposed mechanism for a elementary two-step reaction is analyzed using the potential energy profile shown in the graph. Based on the reaction energy profile, which step is the rate-determining step and what is its activation energy?"
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url: "https://nerd-notes.com/ubq/119234/"
date_modified: "2026-08-19T12:39:29+00:00"
---

# A proposed mechanism for a elementary two-step reaction is analyzed using the potential energy profile shown in the graph. Based on the reaction energy profile, which step is the rate-determining step and what is its activation energy?

A proposed mechanism for a elementary two-step reaction is analyzed using the potential energy profile shown in the graph. Based on the reaction energy profile, which step is the rate-determining step and what is its activation energy?

![A reaction energy profile graph showing potential energy in kJ/mol on the vertical axis against reaction coordinate on the horizontal axis. Horizontal grid lines are drawn at 10, 20, 30, 40, 50, 60, 70, 80, and 90 kJ/mol. A continuous solid black line starts at a flat plateau at 20 kJ/mol labeled Reactants, rises to a peak at 80 kJ/mol labeled TS1, descends to a local minimum well at 50 kJ/mol labeled Intermediate, rises to a second peak at 90 kJ/mol labeled TS2, and descends to a final flat plateau at 10 kJ/mol labeled Products. Axis tick marks and numbers label the potential energy values on the vertical axis from 0 to 100 in increments of 10. No other features, labels, or text appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1787143169-y73Brg.jpg)

- **A.** Step 1, because its activation energy is \(60 \text{ kJ/mol}\), which is greater than the activation energy of Step 2.
- **B.** Step 2, because its transition state reaches the highest overall potential energy at \(90 \text{ kJ/mol}\).
- **C.** Step 1, because its activation energy is \(80 \text{ kJ/mol}\), which is greater than the activation energy of Step 2.
- **D.** Step 2, because its activation energy is \(70 \text{ kJ/mol}\), which is greater than the activation energy of Step 1.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119234/*