Two sodium ions react with two electrons. When they hit this metal, they take up those two electrons, forming two sodium solid molecules or two moles of sodium solid molecules. Now, our net reaction is just an addition of this guy to this guy. Notice that electrons cancel, and we simply get the following net reduction reaction. Now, if we were to look up the electron potentials or the cell potentials for this reaction and this reaction, we would get the following voltages. Now, to find the net or the final cell voltage, we simply add these guys up, and we get negative 4.0
72 volts.