Activity of Mercury in its Amalgams at Molten Stage

Abstract

In the present work we have considered two molten amalgams e.g. sodium amalgam and potassium amalgam. Efforts are made to compute the activity of mercury therein by applying Flory's model. This statistical mechanical model is based on the size factor of the ingredients of a binary liquid alloy. In case of each of the amalgams we have started with the expression for the free energy of mixing (G_M) according to this model. After knowing the ratio of the atomic volumes of the constituent species of an amalgam the prime task becomes the determination of the interchange energy (ω) between them. For this purpose the experimental values of G_M for different concentrations of the ingredients of the amalgam are collected. From these known values ω has been computed by using the expression for G_M. A suitable value of ω is chosen from the set of values so obtained. Putting this value of ω the free energy of mixing is calculated for several concentrations and then compared with its observed values. Accordingly, a modified value of ω has been considered and the calculations are repeated. In this way by the method of successive approximations we have ascertained the value of the interchange energy. Thereafter, with the help of standard thermodynamic relation activity has been computed. The results explain the observed anomaly of the activity of mercury in the present molten amalgams.

Keywords: Binary liquid alloys; Flory's model; Amalgams; Activity of mercury.

DOI: 10.3126/sw.v8i8.3850

Scientific World Vol.8(8) 2010 pp.56-58