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Summary The equilibrium constants for the formation of silver-ammonia complexes in molten (Li, K)NO 3 eutectic mixture were determined from e.m.f. measurements. The results are discussed in connection with the quasi-lattice model for the ionic associations in molten salts.

Summary The interdiffusion coefficient of H 2 O in molten NaOH-KOH (50 mol%) mixture in the temperature range 460–530 K was determined by the chronopotentiometric technique. The standard addition method is proposed for analytical determination of water in molten hydroxides.

Summary The titrations of halides, chromate and “oxide” ions in molten (Li, K)NO 3 with Hg(I), produced by constant current oxidation of mercury, have been studied. The titrations were followed by potentiometric, bipotentiometric and biamperometric techniques. The solubility products of mercurous iodide and mercurous chromate have been determined from e.m.f. measurements in the temperature range, 415–465°K.

Summary The association energy between silver and chromate ions in molten alkali nitrates has been determined from e.m.f. measurements. The results agree with the predictions of the quasi-lattice model for ternary and quaternary reciprocal systems.

Summary The standard potential of the bromine-bromide electrode in molten (Li, K)−NO3 between 410° and 550°K has been determined. The standard potential of the chlorine-chloride electrode in the same solvent, which cannot be determined experimentally, has been calculated from existing data.

Summary The standard potentials of the redox couples involving I 2 , I − , and I 3 − , and the equilibrium constants of the reactions: I 2 ( g ) ⇌ I 2 ( soln ⁡ . ) I 2 ( g ) + I − ⇌ I 3 − in molten (Li,K)NO 3 between 435 and 490°K, have been determined.

Summary Iodide ions were produced in molten (Li, K)NO3 with a 100% current efficiency by constant current reduction of solid silver iodide. This method was applied to the titrations of Ag(I), Hg(I), Hg(II), Cu(II), and Bi(III). The equivalence point was detected by potentiometric, bipotentiometric, and biamperometric techniques; the titration error was generally lower than 1.5%. The reaction between Cu(II) and iodide implies the reduction of copper to insoluble CuI and the evolution of iodine. Nitrate ions take part in the reaction between Bi(III) and iodide, acting both as a base and an oxidant.

Summary The solubility products of silver halides in molten (Li,K) NO 3 and the related thermodynamic quantities have been determined from e.m.f. measurements, and are compared with previous data. The standard electrode potentials of the silversilver halide second-kind electrodes have also been computed.

Summary An apparatus for voltammetric measurements at a platinum spherical microelectrode with periodic renewal of the “diffusion layer” and interrupted polarization is described. The voltammograms obtained give two curves, corresponding to the instantaneous values of the current at two different times after the beginning of each polarization period. It is suggested that the ratio between these two current values can be used as a preliminary diagnostic criterion for assessing the nature of an electrode process.

The validity of the Nernst equation for the silver-silver ion electrode in molten LiClO4-NaClO4 (3:1 mole ratio) was tested. The precipitation of silver halides from the same melt was studied by potentiometric titration; the solubility products and the heats of dissolution were determined.

A new power and energy-to-frequency converter is described. Its operation is based on two closed-loop mean-square value-to-frequency converters of new conception in which a direct digital feedback is used. Error analysis is carried out and performance data of an experimental circuit using indirectly heated thermistors are given. The instrument is suitable for digital power measurement for both dc and ac wide-band signals disregarding its waveform.

The emf of the cell CdAu | CdCl 2 (LiCl, KCl eutectic) | Cl 2 , graphite has been measured over the temperature range 630–730°C with varying mole fraction of cadmium chloride. The thermodynamic data of the liquid mixture CdCl 2 - (LiCl, KCl eutectic) have been determined.

Summary The quasi-lattice treatment of ternary reciprocal systems of molten salts has been extended to quaternary systems of the type (A+, B+, C+, X−, Y−) dilute in A+ and X−. According to the model, the “apparent” association energy between A+ and X− in the mixed “solvent” BY+CY should be a non-linear function of the molar composition of the solvent, and a function of the temperature. The existing experimental data on ion association energies in mixed solvents appear to be insufficient to provide a conclusive test of these predictions.

The application of biamperometry and bipotentiometry to the titration of HgI, SCN−, SbIII and TlI with iodate has been investigated, Probable errors range from 0.16% for SbIII to 0.96% for SCN−, for quantities between 10−5 and 2×10−4moles.

The analysis of halide and cyanide solutions in molten LiNO3-KNO3 at 150° was carried out by titration with electrolytically-generated silver ions. The course of the titration was followed potentiometrically and by biamperometric and bipotentiometric techniques. The titration error for the halides was of the order of minus 1–2 %. A slow decomposition of cyanide solutions was found to take place; this has been attributed to the presence of lithium nitrate in the melt. The solubility products of silver halides and cyanide and the dissociation constant of Ag(CN)2−were determined.

Summary The standard electrode potentials of the Hg/Hg(I), Hg(I)/Hg(II), and Hg/Hg(II) couples, and the equilibrium constant of the reaction Hg+Hg 2+ Hg 2 2+ , in molten (Li,K)NO 3 between 420 and 480°K, have been determined.

Summary The behaviour of Ag | ( Li , K ) NO 3 AgNO 3 | glass | half-cells has been investigated between 150 and 200 o in view of their use as “reference electrodes” in molten (Li,K)NO 3 . Electrodes made from soft-glass are better than Pyrex ones, having lower resistance, higher stability and lower sensitivity to solute cations. When used properly, these electrodes can give potential values accurate within ±0.5 mV.

Summary The association energy between silver(I) and sulphate ions and between silver(I) and molybdate ions in molten alkali nitrates has been determined from e.m.f. measurements. The results agree with the predictions of the quasi-lattice model for ternary and quaternary reciprocal systems.

The equilibrium between molten TlI-PbI2 and a molten alloy Tl-Pb has been studied at the temperatures of 750 and 800°. The activities of the components of the salt phase have been calculated. Es wird das Gleichgewicht zwischen geschmolzenem TlI-PbI2 und der geschmolzenen Legierung Tl-Pb bei 750 und 800° untersucht; die Aktivitaten der in der Salzphase vorhandenen Bestandteile werden berechnet.

The feasibility of the titration of acidic cations in molten sodium nitrate-potassium nitrate with electrolytieally generated oxide ions has been tested. Quantitative data are given for the titration of zinc and cadmium ions.