Abstract
The electrochemistry of mercury was studied with voltammetry and chronoamperometry at glassy carbon and polycrystalline tungsten electrodes in the 
molten salt. The reduction of Hg2+ to Hg in the acidic 66.7‐33.3 mole percent (m/o) melt involves two steps with the intermediate formation of 
, whereas the reduction of 
to Hg in the basic 44.4–55.6 m/o melt proceeds by a single two‐electron step. 
is stable in acidic melt but disproportionates to form 
and Hg metal in basic melt. The electrodeposition of Hg metal on glassy carbon from solutions of 
in acidic melt entails progressive three‐dimensional nucleation on a finite number of active sites with diffusion‐controlled growth of the nuclei. The electrodeposition of Hg metal from solutions of 
in basic melt involves progressive three‐dimensional nucleation on a large number of active sites on tungsten and instantaneous three‐dimensional nucleation on glassy carbon. The diffusion coefficient and Stokes‐Einstein product of 
in acidic melt are 
and 
respectively, at 60°C. The diffusion coefficient and Stokes‐Einstein product of 
in basic melt are 
and 
, respectively, at 40°C. The formal potentials of the 
, 
, and Hg2+/Hg redox couples in acidic melt are 
, 
, respectively, vs. Al(III)/Al in the 66.7‐33.3 m/o melt at 40°C. The formal potential of the 
couple in basic melt is 
vs. this same reference electrode. The equilibrium constant for the disproportionation of 
is 
at 40°C in acidic melt. 
exhibits a single UV‐Vis absorption band at 275 nm 
in the 66.7‐33.3 m/o melt. Hg metal appears to react with 
at 100°C to produce a species with an absorption band at 318 nm. This species is tentatively identified as the 
cluster.