Review Selected properties of simple amalgams

Abstract

Experimental data on solubility, heat and kinetics of dissolution, diffusion and standard potentials of metals in mercury as well as the rate of the electrode process with an amalgam formation, have been collected and selected. A comparison has been made between the measured and predicted solubilities and heats of dissolution. The experimental diffusion coefficients have been analysed according to the simple Sutherland-Einstein equation; the average composition of diffusing particles in diluted amalgams have been estimated. The linear dependence between the logarithm of the rate constant of aquo-ion electroreduction on mercury and the metal solubility in mercury has been confirmed. No correlation of the dissolution rate of metals in mercury has been found. IntroductionIndisputably mercury (Hg), is the metal (M), most frequently used in pure and applied electrochemistry; other applications of mercury in metallurgy, inorganic and organic synthesis, dentistry, electronics, electrotechnics as well as heat transfer, seem to be less significant. From a scientific point of view, liquid mercury and amalgams are generally good models for liquid metals and alloys. For amalgams alone we have a fair collection of reliable data on thermodynamics, solubility and diffusion. Nevertheless, mercury and amalgams are not placed in the main stream of either solution chemistry or metal science.In the present paper an essential collection and evaluation has been achieved of the following data: the type of phase diagram M-Hg, solubility of the metal in mercury, heat and kinetics of dissolution of the metal in mercury, activity and diffusion coefficients of the metal in mercury, standard potentials of amalgams, kinetics of electroreduction of M n+ aquoions on mercury electrode. Most of these features change periodically through the elements table and show mutual interrelations. When possible, the experimental data (solubility, heat of dissolution, diffusion) are compared with theoretical predictions.

Cyclic Voltammetry Probe Approach Curves with Alkali Amalgams at Mercury Sphere-Cap Scanning Electrochemical Microscopy Probes

“…The temporal saturation limit ( T sat ) under diffusion-limited conditions depends primarily on the bulk metal ion concentration ( C ox * ) and the amalgam solubility limit ( C lim ), which varies from ion to ion. For example, the mole fraction solubilities of Li, K, and Na in Hg are 1.33%, 2.53%, and 5.40%, respectively. − Ignoring small changes in amalgam volume, this gives solubility limits of 0.90 M Li­(Hg), 1.7 M K­(Hg), and 3.6 M Na­(Hg). Because amalgamation is not reversible for T > T sat , the range of physically usable T values is limited to T min < T < T sat .…”

Experimental and Theoretical Studies of the Multistability in the Electroreduction of the Nickel(II)−N3-Complexes at a Streaming Mercury Electrode

“…For that purpose the I = ( I f,ss + I c,ss ) = f( E ) functional dependence was fitted to the experimental data from Figure , part A or B, respectively. Some of the parameters, as e.g. , D Ox,1 , D Red,1 , and E pzc were not fitted but were taken from the literature , or determined in our present studies. For significant mathematical simplification of the later numerical determination of the multiple steady states, we used not the potential-dependent, but the constant integral capacitance, averaged over the potential range [−0.8, −1.5 V] within which the NDR regions develop.…”

Experimental and theoretical impedance studies of oscillations and bistability in the Ni(II)–SCN− electroreduction at the streaming mercury electrode

“…Therefore the fixed value k app s;1 ¼ 1:0 Â 10 À3 cm s À1 was assumed (as strongly justified by the results of earlier studies on the Ni(II)-SCN À electrode kinetics [33]). Also the diffusion coefficient of Ni in mercury (D red = 6.5 · 10 À6 cm 2 s À1 ) was taken from the literature [34] and used as a fixed parameter. These problems of course suggest the limited reliability of the fitted parameters, in terms of Eq.…”