Consider a galvanic cell based on the overall reaction Sn (aq) + 2 Fe (aq) → Sn (aq)…
CHEMISTRY · Single correct · AP · Chemistry · Thermodynamics and Electrochemistry · Thermodynamics and Electrochemistry
Problem
Consider a galvanic cell based on the overall reaction
Sn2+ (aq) + 2 Fe3+ (aq) → Sn4+ (aq) + 2 Fe2+ (aq).
Both half-cells initially contain 1.0 M solutions of the indicated ions. After the cell has been assembled, pure water is added to the cathode compartment only, doubling its volume but leaving the anode unchanged. Which statement best describes the immediate effect on the cell potential?
(a) The potential increases because dilution lowers Q, moving the system farther from equilibrium.
(b) The potential is essentially unchanged because the ratio [Fe2+]/[Fe3+] is unaffected, leaving Q nearly the same.
(c) The potential decreases because the lower ionic concentrations reduce the activities of the cathode species, diminishing the driving force for electron flow even if their ratio is unchanged.
(d) The potential changes sign because diluting the cathode solution removes enough oxidizing power from Fe3+ to force the cell reaction to run in reverse.