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title: "The reaction coordinate diagram below represents two competing pathways for the reaction of a single reactant, \\(\\text{R}\\), to form either product \\(\\text{P}_1\\) (dashed curve) or product \\(\\text{P}_2\\) (solid curve).  When the reaction is carried out at \\(200\\text{ K}\\), \\(\\text{P}_1\\) is the predominant product formed. When the reaction is carried out at \\(500\\text{ K}\\) and allowed to reach equilibrium, \\(\\text{P}_2\\) is the predominant product in the mixture. Which of the following statements best explains these experimental observations based on the diagram?"
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url: "https://nerd-notes.com/ubq/121505/"
date_modified: "2026-08-23T05:04:54+00:00"
---

# The reaction coordinate diagram below represents two competing pathways for the reaction of a single reactant, \(\text{R}\), to form either product \(\text{P}_1\) (dashed curve) or product \(\text{P}_2\) (solid curve).

When the reaction is carried out at \(200\text{ K}\), \(\text{P}_1\) is the predominant product formed. When the reaction is carried out at \(500\text{ K}\) and allowed to reach equilibrium, \(\text{P}_2\) is the predominant product in the mixture. Which of the following statements best explains these experimental observations based on the diagram?

The reaction coordinate diagram below represents two competing pathways for the reaction of a single reactant, \(\text{R}\), to form either product \(\text{P}_1\) (dashed curve) or product \(\text{P}_2\) (solid curve).

When the reaction is carried out at \(200\text{ K}\), \(\text{P}_1\) is the predominant product formed. When the reaction is carried out at \(500\text{ K}\) and allowed to reach equilibrium, \(\text{P}_2\) is the predominant product in the mixture. Which of the following statements best explains these experimental observations based on the diagram?

![A reaction energy profile graph with bare axes and no gridlines. The horizontal x-axis is labeled Reaction Coordinate with an arrow pointing to the right. The vertical y-axis is labeled Gibbs Free Energy, \(G\), with an arrow pointing upward. A flat horizontal line segment on the left represents reactant \(\text{R}\) at an intermediate free energy level. Two curves emerge from \(\text{R}\). The first curve is a dashed line that rises to a moderate peak labeled \(\text{TS}_1\) and descends to a flat horizontal line segment labeled \(\text{P}_1\), positioned below the energy of \(\text{R}\). The second curve is a solid line that rises to a higher peak labeled \(\text{TS}_2\) (higher than \(\text{TS}_1\)) and descends to a flat horizontal line segment labeled \(\text{P}_2\), positioned below the energy of \(\text{P}_1\). No other particles, labels, text, or annotations appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1787461494-w1FM2V.jpg)

- **A.** At \(200\text{ K}\), the reaction is under thermodynamic control because \(\text{P}_1\) forms more rapidly over the lower activation energy barrier, whereas at \(500\text{ K}\), the reaction shifts to kinetic control as \(\text{P}_2\) is stabilized.
- **B.** At \(200\text{ K}\), the reaction is under kinetic control because \(\text{P}_1\) has a more negative standard free energy change (\(\Delta G^\circ\)), whereas at \(500\text{ K}\), the reaction is under thermodynamic control because \(\text{P}_2\) has a lower activation energy.
- **C.** At \(200\text{ K}\), the reaction is under thermodynamic control because the lower temperature prevents the decomposition of \(\text{P}_1\), whereas at \(500\text{ K}\), the higher temperature increases the activation energy of the pathway to \(\text{P}_1\).
- **D.** At \(200\text{ K}\), the reaction is under kinetic control because the lower activation energy of Pathway 1 allows \(\text{P}_1\) to form faster, whereas at \(500\text{ K}\), the reaction is under thermodynamic control because sufficient thermal energy enables equilibrium to favor the more stable product, \(\text{P}_2\).

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/121505/*