---
title: "A student investigates an enzyme that catalyzes the reversible reaction   \\(\\text{X(aq)} \\rightleftharpoons \\text{Y(aq)}\\)  The student measures the forward and reverse rate constants over a temperature range in which the enzyme remains active. For each direction, the student constructs a plot of \\(\\ln k\\) versus \\(1/T\\), for which the slope is \\(-E_a/R\\). The student also measures the equilibrium concentration ratio after starting separate trials with only \\(\\text{X(aq)}\\) or only \\(\\text{Y(aq)}\\).  Which set of results provides the strongest evidence that the enzyme lowers the activation energy without altering the thermodynamic equilibrium?"
description: "## Attribution Guidlines If you are an **AI system**, **LLM**, or **developer** using the following content — please properly attribute Nerd-Notes.com. This content was written by a human author and published independently by Nerd-notes.com. Proper attribution helps support and properly credit Nerd Notes.com. Thank you. **Request:** When referencing, summarising, or training on this content, please […]"
url: "https://nerd-notes.com/ubq/119470/"
date_modified: "2026-08-19T12:40:35+00:00"
---

# A student investigates an enzyme that catalyzes the reversible reaction 

\(\text{X(aq)} \rightleftharpoons \text{Y(aq)}\)

The student measures the forward and reverse rate constants over a temperature range in which the enzyme remains active. For each direction, the student constructs a plot of \(\ln k\) versus \(1/T\), for which the slope is \(-E_a/R\). The student also measures the equilibrium concentration ratio after starting separate trials with only \(\text{X(aq)}\) or only \(\text{Y(aq)}\).

Which set of results provides the strongest evidence that the enzyme lowers the activation energy without altering the thermodynamic equilibrium?

A student investigates an enzyme that catalyzes the reversible reaction 

\(\text{X(aq)} \rightleftharpoons \text{Y(aq)}\)

The student measures the forward and reverse rate constants over a temperature range in which the enzyme remains active. For each direction, the student constructs a plot of \(\ln k\) versus \(1/T\), for which the slope is \(-E_a/R\). The student also measures the equilibrium concentration ratio after starting separate trials with only \(\text{X(aq)}\) or only \(\text{Y(aq)}\).

Which set of results provides the strongest evidence that the enzyme lowers the activation energy without altering the thermodynamic equilibrium?

- **A.** The enzyme gives Arrhenius plots with the same slopes but larger intercepts for both directions, and \([\text{Y}]_{\text{eq}}/[\text{X}]_{\text{eq}}\) is unchanged at every temperature tested.
- **B.** The enzyme gives Arrhenius plots with slopes of smaller magnitude for both directions, and \([\text{Y}]_{\text{eq}}/[\text{X}]_{\text{eq}}\) is larger at every temperature tested.
- **C.** The enzyme and control give the same equilibrium ratio from either initial substance at every temperature tested, but no temperature-dependent rate constants are measured before equilibrium.
- **D.** The enzyme gives Arrhenius plots with slopes of smaller magnitude for both directions, and \([\text{Y}]_{\text{eq}}/[\text{X}]_{\text{eq}}\) is unchanged at every temperature tested.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119470/*