Question

An electrochemical cell is set up by combining two half cells given in the cell notation below. Ca^2+ Ca||Pb/Pb^2+. Which half-cell is the cathode? What half-cell is the anode?

a) Cathode: Ca^2+, Anode: Pb
b) Cathode: Pb, Anode: Ca^2+
c) Cathode: Pb, Anode: Pb^2+
d) Cathode: Ca^2+, Anode: Pb^2+

Answer 1

In the electrochemical cell Ca^2+ Ca||Pb/Pb^2+, the cathode where reduction occurs is the lead electrode (Pb), and the anode where oxidation occurs is the calcium electrode (Ca). Thus, the cell notation indicates that the cathode is Pb and the anode is Ca, making the cathode positive and the anode negative.

Step-by-step explanation:

To determine which half-cell is the cathode and which is the anode in the electrochemical cell represented by the cell notation Ca2+ Ca||Pb/Pb2+, we need to look at the oxidation and reduction half-reactions. In general, the anode is where oxidation occurs, and it is the negative electrode, while the cathode is where reduction occurs, and it is the positive electrode.

Anode half-reaction: Ca(s) -> Ca2+(aq) + 2e-

Cathode half-reaction: Pb2+(aq) + 2e- -> Pb(s)

Since calcium is going from a neutral state to a 2+ charge state, it is being oxidized, and therefore, the calcium electrode is the anode. The lead is going from a 2+ charge to a neutral state, and it gets reduced, making the lead electrode the cathode. Hence, the correct answer is (b) Cathode: Pb, Anode: Ca. The anode is negative, and the cathode is positive in a standard galvanic cell.