This equation predicts lower E red at higher pH values. This is observed for the reduction of O 2 into H 2 O, or OH, and for the reduction of H into H 2. E red is then often noted as E h to indicate that it refers to the standard hydrogen electrode (SHE) whose E red = 0 by convention under standard conditions (T = 298.15 K = 25 °C = 77 F, P gas = 1 atm (1.013 bar), concentrations = 1 M and thus pH = 0).