A galvanic cell is constructed using a solid aluminum electrode immersed in 1.0 M Al(NO3)3(aq) in one half-cell and a solid nickel electrode immersed in 1.0 M Ni(NO3)2(aq) in the other half-cell. The two half-cells are connected by a salt bridge containing KNO3(aq), and an external circuit allows electrons to flow freely between the electrodes. The cell operates until an external ammeter registers that 0.050 mol of electrons have passed through the circuit.
(a) Identify which electrode functions as the anode and which functions as the cathode. State the direction of electron flow through the external wire.
(b) Describe qualitatively how the mass of each metallic electrode changes as the cell operates, and explain the chemical process responsible for each change.
(c) Indicate which ion (K+ or NO3−) migrates toward each half-cell through the salt bridge, and justify your answer in terms of charge balance.
(d) Describe any visible changes that would be expected on the surface of each electrode after the passage of 0.050 mol of electrons.