Compare a battery made from the following pairs of aqueous half cells: Mg⁺⁺ + 2e^- ↔ Mg(s) and Cu⁺⁺ + 2 e^- ↔ Cu(s) with Fe⁺⁺ + 2 e^- ↔ Fe(s) and Ag⁺ + e^- ↔ Ag(s). What will be the voltages and can you speculate on the relative weights of the batteries if the densities of Mg(s), Cu(s), Fe(s), and Ag(s) are 1740, 7190, 7780, and 10,500 kg/m3, respectively? A significant part of the weight of an electrochemical cell is the weight of its electrodes.