---
title: "A student adds a piece of solid zinc to an aqueous solution of hydrochloric acid, as represented by the balanced equation below:  \\[\\text{Zn}(s) + 2\\text{HCl}(aq) \\rightarrow \\text{ZnCl}_2(aq) + \\text{H}_2(g)\\]  Which of the following best predicts and justifies the sign of the standard entropy change, \\(\\Delta S^\\circ\\), for this reaction?"
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url: "https://nerd-notes.com/ubq/119271/"
date_modified: "2026-08-19T12:39:36+00:00"
---

# A student adds a piece of solid zinc to an aqueous solution of hydrochloric acid, as represented by the balanced equation below:

\[\text{Zn}(s) + 2\text{HCl}(aq) \rightarrow \text{ZnCl}_2(aq) + \text{H}_2(g)\]

Which of the following best predicts and justifies the sign of the standard entropy change, \(\Delta S^\circ\), for this reaction?

A student adds a piece of solid zinc to an aqueous solution of hydrochloric acid, as represented by the balanced equation below:

\[\text{Zn}(s) + 2\text{HCl}(aq) \rightarrow \text{ZnCl}_2(aq) + \text{H}_2(g)\]

Which of the following best predicts and justifies the sign of the standard entropy change, \(\Delta S^\circ\), for this reaction?

- **A.** \(\Delta S^\circ > 0\), because the reaction is exothermic and transfers heat energy to the surroundings.
- **B.** \(\Delta S^\circ < 0\), because the total number of moles of products is less than the total number of moles of reactants.
- **C.** \(\Delta S^\circ > 0\), because a gas is produced from solid and aqueous reactants, leading to a net increase in matter dispersal.
- **D.** \(\Delta S^\circ < 0\), because the formation of aqueous zinc ions restricts the motion of surrounding water molecules.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119271/*