A laboratory technician compares how much electrical charge is required to deposit…
CHEMISTRY · Multi-part · AP · Chemistry · Thermodynamics and Electrochemistry · Thermodynamics and Electrochemistry
Problem
A laboratory technician compares how much electrical charge is required to deposit identical molar amounts of metal from two aqueous salt solutions. Solution X contains Cu2+ ions, while Solution Y contains Cr3+ ions. In both electroplating cells, the cathode has the same surface area and is run for identical amounts of time, but different steady currents are selected so that exactly 1.00×10−3mol of metal is deposited in each case.
(a) Describe the relationship between the total electrical charge that passes through an electrolysis cell and the amount of metal deposited at the cathode.
(b) Explain, without numerical calculation, why depositing 1.00×10−3mol of chromium requires more total charge than depositing the same amount of copper.
(c) The technician accidentally sets both power supplies to the same current. Predict which cell will finish depositing its 1.00×10−3mol first and justify your answer using electron–ion stoichiometry.