Chloride:

The standard potentials vs. NHE of the fundamental couples including uncomplexed Hg (I) and Hg (II) ions are Applications of Coulometry ,Conductometry, and Electrogravimetry

Hg₂²⁺ + 2e → 2Hg     E⁰   = +0.80V

Hg²⁺ + 2e → Hg E⁰ = + 0.88V

2Hg²⁺ + 2e → Hg₂²⁺ E⁰ =   + 0.91V

The oxidation of Hg to Hg₂^{2 +}   needs a smaller potential than to Hg²⁺. Hg (I) ions are the products while a mercury electrode is subjected to anode polarization within a non-complexing medium. From the stoichemetric point is does not matter whether oxidation of a mercury anode produces Hg (I) or Hg (II) salt of a provide anion, because the similar quantity of electricity per mole of anion is included in either case i.e. the similar number of coulombs per mole of the anion are needed to join either Hg₂Cl₂  or HgCl₂.