A student constructs a galvanic cell by coupling a strip of solid zinc in a 1.0 M solution of ZnSO4 with a strip of solid copper in a 1.0 M solution of CuSO4. The porous barrier that separates the two half-cells allows ions to migrate but prevents bulk mixing of the solutions.
During the first several minutes of operation, the student observes that the mass of the zinc electrode decreases while the mass of the copper electrode increases.
Answer the following questions about the flow of electric charge in this cell and its relationship to the chemical changes taking place.
(a) Describe, in terms of electron movement, why the decrease in mass of the zinc electrode must be accompanied by an equal but opposite gain of electrons elsewhere in the cell.
(b) The student proposes that the cell could operate even if the number of electrons lost at the zinc electrode did not exactly equal the number gained at the copper electrode. Explain why this proposal violates a fundamental conservation law and predict what macroscopic observation would reveal the violation if it actually occurred.
(c) Using particulate-level reasoning, distinguish between the oxidation process occurring at the zinc electrode and the reduction process occurring at the copper electrode, specifically highlighting how charge balance is preserved in each half-cell.