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title: "A student constructs a galvanic cell based on the following overall reaction:  \\[ \\text{Zn}(s) + 2\\,\\text{Ag}^+(aq) \\rightarrow \\text{Zn}^{2+}(aq) + 2\\,\\text{Ag}(s) \\]  The cell is assembled with a strip of \\(\\text{Zn}(s)\\) in \\(1.0 \\text{ M } \\text{Zn(NO}_3)_2(aq)\\) and a strip of \\(\\text{Ag}(s)\\) in \\(1.0 \\text{ M } \\text{AgNO}_3(aq)\\), separated by a porous glass barrier. The porous barrier was previously stored in a concentrated \\(\\text{NaCl}(aq)\\) solution and was improperly cleaned before use, retaining residual \\(\\text{Cl}^-(aq)\\). Upon assembly, a small amount of white \\(\\text{AgCl}(s)\\) precipitate is observed at the barrier in the silver half-cell. Which of the following describes the effect of this error on the initial measured cell potential compared to the expected standard cell potential, \\(E^\\circ_{\\text{cell}}\\), and provides the correct justification?"
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url: "https://nerd-notes.com/ubq/120351/"
date_modified: "2026-08-23T04:23:20+00:00"
---

# A student constructs a galvanic cell based on the following overall reaction:

\[ \text{Zn}(s) + 2\,\text{Ag}^+(aq) \rightarrow \text{Zn}^{2+}(aq) + 2\,\text{Ag}(s) \]

The cell is assembled with a strip of \(\text{Zn}(s)\) in \(1.0 \text{ M } \text{Zn(NO}_3)_2(aq)\) and a strip of \(\text{Ag}(s)\) in \(1.0 \text{ M } \text{AgNO}_3(aq)\), separated by a porous glass barrier. The porous barrier was previously stored in a concentrated \(\text{NaCl}(aq)\) solution and was improperly cleaned before use, retaining residual \(\text{Cl}^-(aq)\). Upon assembly, a small amount of white \(\text{AgCl}(s)\) precipitate is observed at the barrier in the silver half-cell. Which of the following describes the effect of this error on the initial measured cell potential compared to the expected standard cell potential, \(E^\circ_{\text{cell}}\), and provides the correct justification?

A student constructs a galvanic cell based on the following overall reaction:

\[ \text{Zn}(s) + 2\,\text{Ag}^+(aq) \rightarrow \text{Zn}^{2+}(aq) + 2\,\text{Ag}(s) \]

The cell is assembled with a strip of \(\text{Zn}(s)\) in \(1.0 \text{ M } \text{Zn(NO}_3)_2(aq)\) and a strip of \(\text{Ag}(s)\) in \(1.0 \text{ M } \text{AgNO}_3(aq)\), separated by a porous glass barrier. The porous barrier was previously stored in a concentrated \(\text{NaCl}(aq)\) solution and was improperly cleaned before use, retaining residual \(\text{Cl}^-(aq)\). Upon assembly, a small amount of white \(\text{AgCl}(s)\) precipitate is observed at the barrier in the silver half-cell. Which of the following describes the effect of this error on the initial measured cell potential compared to the expected standard cell potential, \(E^\circ_{\text{cell}}\), and provides the correct justification?

- **A.** The initial measured cell potential is less than \(E^\circ_{\text{cell}}\) because the precipitation of \(\text{AgCl}(s)\) decreases \([\text{Ag}^+]\), which increases \(Q\) above \(1\).
- **B.** The initial measured cell potential is less than \(E^\circ_{\text{cell}}\) because the precipitation of \(\text{AgCl}(s)\) consumes electrons directly at the barrier, reducing the value of \(n\) in the cell potential equation.
- **C.** The initial measured cell potential is greater than \(E^\circ_{\text{cell}}\) because the precipitation of \(\text{AgCl}(s)\) decreases \([\text{Ag}^+]\), which decreases \(Q\) and shifts the system further from equilibrium.
- **D.** The initial measured cell potential is equal to \(E^\circ_{\text{cell}}\) because \(\text{AgCl}(s)\) is an insoluble solid that does not appear in the expression for \(Q\), leaving the cell potential unaffected.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/120351/*