Question

Mg(s)/Mg^2+(aq)//Al^3+(aq)/Al(s)
1. Give the overall balanced cell reaction
2. Provide the half reaction for the galvanic cell line notation
3. Calculate the E°cell for the galvanic cell and comment on its value

Answer 1

1. Overall balanced cell reaction: Mg(s) + 2Al^3+(aq) -> Mg^2+(aq) + 2Al(s)

2. Half reactions:
Anode: Mg(s) -> Mg^2+(aq) + 2e-
Cathode: 2Al^3+(aq) + 6e- -> 2Al(s)

Galvanic cell line notation: Mg(s)|Mg^2+(aq) || Al^3+(aq)|Al(s)

3. E°cell = E°cathode - E°anode
E°cell = -1.67 V - (-2.37 V) = 0.70 V

The positive E°cell value indicates that the cell reaction is spontaneous and has a driving force to proceed in the forward direction. This means that the reduction of Al^3+ to Al at the cathode is favored over the oxidation of Mg to Mg^2+ at the anode.