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[en] As far as a multicomponent mixture is concerned, different versions exist in the literature for the relationship between the partial molar and molar quantity of a thermodynamic state function with the most prominent example of the two quantities being the activity coefficient of an arbitrary component and the excess Gibbs free energy of a mixture comprising this component. Since the relationships published so far have to a large degree been derived independently of each other and result from apparently conflicting approaches, they are still considered as separate subjects in the literature. It is demonstrated that despite this curious situation all relationships are equivalent to each other from a mathematical point of view

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[en] The chemical forms of sulphate on a strong base anion resin made in China have been investigated by means of equivalent accounting and I.R. spectroscopy. The ion exchange isotherm, selectivity coefficient and corrected selectivity coefficient for SO₄^2-/Cl^- have been determined. The rational equilibrium constant and rational activity coefficients of the resinates have been calculated by using the Gaines and Thomas thermodynamics formula

[en] In a continuing survey of the relative reactivities of higher fluorides of d- and f-transition elements, redox reactions of protactinium pentafluoride with selected reductants have been studied. Halogen-exchange reactions with covalent chlorides have been investigated for both the pentafluoride and tetrafluoride. The results of these reactions are correlated with those from previous investigations. Special attention was given to preparative and reaction techniques because of the radioactive nature and because of the small quantities of the compounds available for this work compared with the scale of earlier related studies in this series. (author)

[en] The Ag/AgCl electrode is a type of reference electrode, commonly used in electrochemical measurements, because it is simple, inexpensive, very stable and non-toxic. For these reasons, the Ag/AgCl electrode has long been used to provide a reliable potential monitoring of ions in a solution. However, when a reference electrode is immersed in a solution for a long period of time, this can cause an electrolyte leakage. If the reference electrode does not maintain its reference potential due to an electrolyte leakage, a number of undesirable conditions may occur. As the potential of the Ag/AgCl electrode is determined by the activity of chloride ions in a solution, a number of investigations have been performed on the prevention of an electrolyte leakage. However, these attempts have not resolved the problem of an electrolyte leakage satisfactorily through a junction between a reference electrode and a test solution. In the present work, we demonstrate a new method to calibrate Ag/AgCl reference electrodes. The concept of this method is that the concentration of KCl can be estimated by the electrical conductivity of the electrolyte, and then the potential of the Ag/AgCl reference electrode is calculated by the Nernst equation, with the estimated KCl concentration at a given temperature

[en] A modified associate formalism is proposed for thermodynamic modelling of solution phases. The approach is free from the entropy paradox described by Lueck et al. [R. Lueck, U. Gerling, B. Predel, Zeitschrift fur Metallkunde 80 (1989) 270-275]. The model is considered in its general form for an arbitrary number of solution components and an arbitrary size of associates. Asymptotic behaviour of chemical activities of solution components in binary dilute solutions is also investigated