A voltaic cell is constructed in which the following cell reaction occurs. The half-cell compartments are connected by a bridge. Co^2+(aq) + Mg(s) rightarrow Co(s) + Mg^2+(aq) The anode reaction is: + rightarrow + The cathode reaction is: + rightarrow + In the external circuit, electrons migrate the Mg|Mg^2+ electrode the Co|Co^2+ electrode. In the salt bridge, anions migrate the Co|Co^2+ compartment the Mg|Mg^2+ compartment.