Standard electrode potential to produce an electric potential, Gibbs free energy Δ"G"° must be negative, in accordance with the following equation: where "n" is number of moles of electrons per mole of products and "F" is the Faraday constant, ~96485 C/mol. As such, the following rules apply: Thus in order to have a spontaneous reaction (ΔG° < 0), "E"° must be positive, where: where "E"° is the standard potential at the anode and "E"° is the standard potential at the cathode as given in the table of standard electrode potential. Standard electrode potential In electrochemistry, it is defined as the measure of the
Standard hydrogen electrode Standard hydrogen electrode The Standard hydrogen electrode (abbreviated SHE), is a redox electrode which forms the basis of the thermodynamic scale of oxidation-reduction potentials. Its absolute electrode potential is estimated to be at 25 °C, but to form a basis for comparison with all other electrode reactions, hydrogen's standard electrode potential ("E") is declared to be zero volts only at 298K. Potentials of any other electrodes are compared with that of the standard hydrogen electrode at the same temperature. Hydrogen electrode is based on the redox half cell: This redox reaction occurs at a platinized platinum electrode. The electrode is