---
title: "A student constructs a concentration cell to model the transfer of copper ions between two recycling streams. Two equal-volume solutions of \\(\\text{CuSO}_4\\text{(aq)}\\), initially \\(1.0\\text{ M}\\) and \\(0.010\\text{ M}\\), are connected by a salt bridge. A \\(\\text{Cu(s)}\\) electrode is placed in each solution, and the electrodes are connected through an external circuit. As the cell operates at constant temperature, the student records the following data.  | Stage | \\(\\dfrac{[\\text{Cu}^{2+}]_{\\text{high}}}{[\\text{Cu}^{2+}]_{\\text{low}}}\\) | \\(E_{\\text{cell}}\\) (V) | |—|—:|—:| | Initial | 100 | 0.059 | | Later | 10 | 0.030 | | Later | 2 | 0.009 | | Equilibrium | 1 | 0.000 |  Which statement best explains why the measured cell potential approaches \\(0.000\\text{ V}\\)?"
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url: "https://nerd-notes.com/ubq/119488/"
date_modified: "2026-08-19T12:40:42+00:00"
---

# A student constructs a concentration cell to model the transfer of copper ions between two recycling streams. Two equal-volume solutions of \(\text{CuSO}_4\text{(aq)}\), initially \(1.0\text{ M}\) and \(0.010\text{ M}\), are connected by a salt bridge. A \(\text{Cu(s)}\) electrode is placed in each solution, and the electrodes are connected through an external circuit. As the cell operates at constant temperature, the student records the following data.

| Stage | \(\dfrac{[\text{Cu}^{2+}]_{\text{high}}}{[\text{Cu}^{2+}]_{\text{low}}}\) | \(E_{\text{cell}}\) (V) |
|—|—:|—:|
| Initial | 100 | 0.059 |
| Later | 10 | 0.030 |
| Later | 2 | 0.009 |
| Equilibrium | 1 | 0.000 |

Which statement best explains why the measured cell potential approaches \(0.000\text{ V}\)?

A student constructs a concentration cell to model the transfer of copper ions between two recycling streams. Two equal-volume solutions of \(\text{CuSO}_4\text{(aq)}\), initially \(1.0\text{ M}\) and \(0.010\text{ M}\), are connected by a salt bridge. A \(\text{Cu(s)}\) electrode is placed in each solution, and the electrodes are connected through an external circuit. As the cell operates at constant temperature, the student records the following data.

| Stage | \(\dfrac{[\text{Cu}^{2+}]_{\text{high}}}{[\text{Cu}^{2+}]_{\text{low}}}\) | \(E_{\text{cell}}\) (V) |
|---|---:|---:|
| Initial | 100 | 0.059 |
| Later | 10 | 0.030 |
| Later | 2 | 0.009 |
| Equilibrium | 1 | 0.000 |

Which statement best explains why the measured cell potential approaches \(0.000\text{ V}\)?

- **A.** The measured cell potential approaches zero because the standard reduction potential of each \(\text{Cu}^{2+}\text{(aq)}/\text{Cu(s)}\) half-cell decreases as copper ions are transferred.
- **B.** The measured cell potential approaches zero because the migration of salt-bridge ions restores electrical neutrality in each solution, eliminating the need for electron flow.
- **C.** The measured cell potential approaches zero because both oxidation and reduction cease completely when the cell reaches equilibrium.
- **D.** The measured cell potential approaches zero because the reaction quotient reaches the equilibrium constant, making \(\Delta G=0\); since \(\Delta G=-nFE_{\text{cell}}\), \(E_{\text{cell}}=0\).

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119488/*