to atmospheric pressure) and further the reaction is carried out at 298K, then the potential of each electrode is said to be the Standard Electrode Potential . By convention, the standard electrode potential (E ) of hydrogen electrode is . volts. The electrode potential value for each electrode process is a measure of the relative tendency of the active species in the process to remain in the oxidised/reduced form.
A negative E means that the redox couple is a stronger Fig. . The set-up for Daniell cell. Electrons produced at the anode due to oxidation of Zn travel through the external circuit to the cathode where these reduce the copper ions.
The circuit is completed inside the cell by the migration of ions through the salt bridge. It may be noted that the direction of current is opposite to the direction of electron flow. Reaction (Oxidised form + n e – → Reduced form) E / V F (g) + 2e – → 2F – . Co + + e – → Co + .
H O + 2H + + 2e – → 2H O . – + 8H + + 5e – → Mn + + 4H O . Au + + 3e – → Au(s) . Cl (g) + 2e – → 2Cl – .
– + 14H + + 6e – → 2Cr + + 7H O . O (g) + 4H + + 4e – → 2H O . MnO (s) + 4H + + 2e – → Mn + + 2H O . Br + 2e – → 2Br – .
NO – + 4H + + 3e – → NO(g) + 2H O . 2Hg + + 2e – → Hg + . Ag + + e – → Ag(s) . Fe + + e – → Fe + .