---
title: "A student constructs a galvanic cell under standard conditions, as shown in the diagram. One half-cell consists of a \\( \\text{Zn(s)} \\) strip immersed in \\( 1.0\\text{ M Zn(NO}_3)_2\\text{(aq)} \\). The other half-cell consists of a solid graphite rod immersed in an aqueous solution containing \\( 1.0\\text{ M Fe(NO}_3)_3\\text{(aq)} \\) and \\( 1.0\\text{ M Fe(NO}_3)_2\\text{(aq)} \\). The relevant standard reduction potentials are given below.  \\[ \\text{Fe}^{3+}\\text{(aq)} + \\text{e}^- \\rightarrow \\text{Fe}^{2+}\\text{(aq)} \\quad E^\\circ = +0.77\\text{ V} \\] \\[ \\text{Zn}^{2+}\\text{(aq)} + 2\\text{e}^- \\rightarrow \\text{Zn(s)} \\quad E^\\circ = -0.76\\text{ V} \\]  After current is allowed to flow through the circuit for \\( 10\\text{ minutes} \\), both electrodes are removed, rinsed with distilled water, dried, and weighed. Which of the following statements best explains why the mass of the graphite electrode does not change as the cell operates?"
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url: "https://nerd-notes.com/ubq/123951/"
date_modified: "2026-09-28T12:32:30+00:00"
---

# A student constructs a galvanic cell under standard conditions, as shown in the diagram. One half-cell consists of a \( \text{Zn(s)} \) strip immersed in \( 1.0\text{ M Zn(NO}_3)_2\text{(aq)} \). The other half-cell consists of a solid graphite rod immersed in an aqueous solution containing \( 1.0\text{ M Fe(NO}_3)_3\text{(aq)} \) and \( 1.0\text{ M Fe(NO}_3)_2\text{(aq)} \). The relevant standard reduction potentials are given below.

\[ \text{Fe}^{3+}\text{(aq)} + \text{e}^- \rightarrow \text{Fe}^{2+}\text{(aq)} \quad E^\circ = +0.77\text{ V} \]
\[ \text{Zn}^{2+}\text{(aq)} + 2\text{e}^- \rightarrow \text{Zn(s)} \quad E^\circ = -0.76\text{ V} \]

After current is allowed to flow through the circuit for \( 10\text{ minutes} \), both electrodes are removed, rinsed with distilled water, dried, and weighed. Which of the following statements best explains why the mass of the graphite electrode does not change as the cell operates?

A student constructs a galvanic cell under standard conditions, as shown in the diagram. One half-cell consists of a \( \text{Zn(s)} \) strip immersed in \( 1.0\text{ M Zn(NO}_3)_2\text{(aq)} \). The other half-cell consists of a solid graphite rod immersed in an aqueous solution containing \( 1.0\text{ M Fe(NO}_3)_3\text{(aq)} \) and \( 1.0\text{ M Fe(NO}_3)_2\text{(aq)} \). The relevant standard reduction potentials are given below.

\[ \text{Fe}^{3+}\text{(aq)} + \text{e}^- \rightarrow \text{Fe}^{2+}\text{(aq)} \quad E^\circ = +0.77\text{ V} \]
\[ \text{Zn}^{2+}\text{(aq)} + 2\text{e}^- \rightarrow \text{Zn(s)} \quad E^\circ = -0.76\text{ V} \]

After current is allowed to flow through the circuit for \( 10\text{ minutes} \), both electrodes are removed, rinsed with distilled water, dried, and weighed. Which of the following statements best explains why the mass of the graphite electrode does not change as the cell operates?

![A schematic diagram of a galvanic cell with two separate beakers connected by an inverted U-shaped salt bridge and an external wire with a voltmeter. The left beaker contains a light gray solid strip labeled Zn(s) immersed in a solution labeled 1.0 M Zn(NO3)2(aq). The right beaker contains a dark gray solid rod labeled C(graphite) immersed in a solution labeled 1.0 M Fe(NO3)3(aq) and 1.0 M Fe(NO3)2(aq). The external wire connects the two electrodes through a circular voltmeter labeled V. The inverted U-tube is labeled KNO3(aq) salt bridge with open ends dipping into each solution. An arrow alongside the top wire indicates electron flow directed from the Zn(s) electrode toward the C(graphite) electrode. No other particles, labels, text, or annotations appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1790598749-adDjzj.jpg)

- **A.** The mass remains unchanged because the reduction half-reaction converts dissolved \( \text{Fe}^{3+}\text{(aq)} \) into dissolved \( \text{Fe}^{2+}\text{(aq)} \), with the graphite acting solely as a conductive surface for electron transfer without depositing a solid product.
- **B.** The mass remains unchanged because the rate of solid \( \text{Fe(s)} \) deposition onto the electrode surface is dynamically balanced by the rate of solid \( \text{Fe(s)} \) re-dissolving into the solution.
- **C.** The mass increases because the reduction of \( \text{Fe}^{3+}\text{(aq)} \) by incoming electrons produces metallic \( \text{Fe(s)} \) that precipitates onto the surface of the graphite rod.
- **D.** The mass decreases because carbon atoms from the graphite rod lose electrons and dissolve as solvated ions to complete the electrical circuit.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123951/*