Mercury halides molten salts

In conclusion, it appears that few metal-molten salt systems behave in the ideally polarizable sense generally associated with the mercury/aqueous solution interface at 298 K. Possible exceptions include some noble liquid metal/melt systems such as mercury/molten nitrates and lead/molten halides at low temperatures (<773 K), but only when the molten electrolyte is extensively purified. Otherwise, systems need to be analyzed as complex impedances, using ac or pulse techniques, to determine whether the minimum interfacial capacitance is affected by extensive factors, leading to parallel pseudocapacitances and Faradaic components. The range of potentials and measuring frequencies for which the interface approaches ideally polarizable behavior also needs to be established. It now seems clear that the multilayer ionic model of charge distribution at the metal/melt interface is more pertinent to molten media than the familiar double layer associated with aqueous solutions. However, the quantitative theories derived for the former model will have to be revised if it is confirmed that the interfacial capacitance is, indeed, independent of temperature in the ideally polarizable region. 

A dissolution mechanism for zinc, cadmium and mercury in their molten halides has been proposed on the basis of experimental and literature data.949 Dissolution occurs at the metal-salt phase boundary. Adsorbed M24- cations are reduced to M+ ions which then migrate into the salt phase where Mi4" dimers form. The stability of the M2+ ions was found to increase in the order Zn < Cd Hg (the latter is so stable that Hg+ is undetectable in solution). 

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