Silver plating is commonly performed by passing a direct current through an aqueous…
CHEMISTRY · Multi-part · AP · Chemistry · Thermodynamics and Electrochemistry · Thermodynamics and Electrochemistry
Problem
Silver plating is commonly performed by passing a direct current through an aqueous AgNO3 solution so that Ag+ ions are reduced to metallic silver at the cathode.
The reduction half-reaction is
Ag+(aq) + e− → Ag(s)
Assume all silver ions in solution are monovalent and that no side reactions occur.
(a) Explain, without performing numerical calculations, why passing exactly one Faraday of charge through this cell deposits one mole of silver atoms on the cathode while passing the same charge through a cell that reduces Cu2+ ions deposits only one-half mole of copper atoms.
(b) Describe qualitatively how the mass of silver deposited changes if the current supplied to the cell is doubled while the electrolysis time is halved, and justify your reasoning based on the relationship among current, time, and charge.
(c) Current efficiency is defined as the fraction of the total charge that produces the desired product. Identify two experimental factors that can cause the current efficiency of a silver-plating bath to drop below 100 %, and briefly explain the effect of each factor.