---
title: "A student investigates the kinetics of the reaction between solid calcium carbonate and hydrochloric acid, represented by the balanced equation below:  \\[\\text{CaCO}_3\\text{(s)} + 2\\text{HCl(aq)} \\rightarrow \\text{CaCl}_2\\text{(aq)} + \\text{H}_2\\text{O(l)} + \\text{CO}_2\\text{(g)}\\]  In Trial 1, the student adds a single \\(2.0 \\text{ g}\\) chip of \\(\\text{CaCO}_3\\text{(s)}\\) to \\(50.0 \\text{ mL}\\) of \\(1.0 \\text{ M HCl(aq)}\\) at \\(25^\\circ\\text{C}\\) and measures the initial rate of \\(\\text{CO}_2\\text{(g)}\\) production. In Trial 2, the student repeats the experiment using \\(2.0 \\text{ g}\\) of finely powdered \\(\\text{CaCO}_3\\text{(s)}\\) with \\(50.0 \\text{ mL}\\) of \\(1.0 \\text{ M HCl(aq)}\\) at \\(25^\\circ\\text{C}\\). Which of the following best predicts and explains the effect of using powdered \\(\\text{CaCO}_3\\text{(s)}\\) on the initial reaction rate?"
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url: "https://nerd-notes.com/ubq/119292/"
date_modified: "2026-08-19T12:39:41+00:00"
---

# A student investigates the kinetics of the reaction between solid calcium carbonate and hydrochloric acid, represented by the balanced equation below:

\[\text{CaCO}_3\text{(s)} + 2\text{HCl(aq)} \rightarrow \text{CaCl}_2\text{(aq)} + \text{H}_2\text{O(l)} + \text{CO}_2\text{(g)}\]

In Trial 1, the student adds a single \(2.0 \text{ g}\) chip of \(\text{CaCO}_3\text{(s)}\) to \(50.0 \text{ mL}\) of \(1.0 \text{ M HCl(aq)}\) at \(25^\circ\text{C}\) and measures the initial rate of \(\text{CO}_2\text{(g)}\) production. In Trial 2, the student repeats the experiment using \(2.0 \text{ g}\) of finely powdered \(\text{CaCO}_3\text{(s)}\) with \(50.0 \text{ mL}\) of \(1.0 \text{ M HCl(aq)}\) at \(25^\circ\text{C}\). Which of the following best predicts and explains the effect of using powdered \(\text{CaCO}_3\text{(s)}\) on the initial reaction rate?

A student investigates the kinetics of the reaction between solid calcium carbonate and hydrochloric acid, represented by the balanced equation below:

\[\text{CaCO}_3\text{(s)} + 2\text{HCl(aq)} \rightarrow \text{CaCl}_2\text{(aq)} + \text{H}_2\text{O(l)} + \text{CO}_2\text{(g)}\]

In Trial 1, the student adds a single \(2.0 \text{ g}\) chip of \(\text{CaCO}_3\text{(s)}\) to \(50.0 \text{ mL}\) of \(1.0 \text{ M HCl(aq)}\) at \(25^\circ\text{C}\) and measures the initial rate of \(\text{CO}_2\text{(g)}\) production. In Trial 2, the student repeats the experiment using \(2.0 \text{ g}\) of finely powdered \(\text{CaCO}_3\text{(s)}\) with \(50.0 \text{ mL}\) of \(1.0 \text{ M HCl(aq)}\) at \(25^\circ\text{C}\). Which of the following best predicts and explains the effect of using powdered \(\text{CaCO}_3\text{(s)}\) on the initial reaction rate?

- **A.** The initial rate increases because crushing the solid increases the average kinetic energy of the \(\text{CaCO}_3\text{(s)}\) particles, increasing the fraction of collisions with energy equal to or greater than \(E_a\).
- **B.** The initial rate remains unchanged because the mass of \(\text{CaCO}_3\text{(s)}\), temperature, and initial concentration of \(\text{HCl(aq)}\) are identical in both trials.
- **C.** The initial rate increases because crushing the solid exposes a greater surface area, increasing the frequency of collisions per unit time between \(\text{H}^+\text{(aq)}\) ions and \(\text{CaCO}_3\text{(s)}\).
- **D.** The initial rate decreases because smaller particles have less mass per particle, which reduces the force of collision upon impact with \(\text{H}^+\text{(aq)}\) ions.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119292/*