Answer:
Co(s) ------> Co^3+(aq) + 3e
Explanation:
A voltaic cell produces energy by spontaneous chemical processes. A voltaic cell contains an anode and a cathode. Oxidation (electron loss) occurs at the anode while reduction (electron gain) occurs at the cathode.
For the cobalt-silver voltaic cell, the reaction equation of the cobalt and silver voltaic anode half cell is shown;
At the anode;
Co(s) ------> Co^3+(aq) + 3e
Note that the anode is the electrode where oxidation occurs hence electrons are lost at the anode.