Reference Electrodes in Metal Corrosion

Table 2

Electrode	Electrode potential (V)
Standard hydrogen electrode (SHE)	0.0000
H3O^+/H2 water solution, H3O^+ and H2 activity are unity
Copper-copper sulphate electrode	0.316
Cu/CuSO4⋅5H2O (crystal) in saturated water solution of CuSO4⋅5H2O
Calomel electrodes
Hg/Hg2Cl2 (crystal) in saturated water solution of KCl	0.2410
Hg/Hg2Cl2 (crystal) in 1.0 mol/dm^3 w. solution of KCl	0.2801
Hg/Hg2Cl2 (crystal) in 0.1 mol/dm^3 w. solution of KCl	0.3337
Silver-silver chloride electrodes
Ag/AgCl (crystal) in saturated water solution of KCl	0.1970
Ag/AgCl (crystal) in 1.0 mol/dm^3 w. solution of KCl	0.2360
Ag/AgCl (crystal) in 0.1 mol/dm^3 w. solution of KCl	0.2895
Mercury-mercuric oxide electrode
Hg/HgO (crystal) in 0.1 mol/dm^3 w. solution of NaOH	0.165
Mercury-mercurous sulphate electrode
Hg/Hg2SO4 (crystal) in 1.0 mol/dm^3 w. solution of H2SO4	0.6739