In continuation of our studies on the extraction of rhodium from acid nitrate-nitrite aqueous solutions with a mixture of alkylanilinium nitrate and dialkyl sulfide, a back-extraction of rhodium was studied. Thiourea (TU) is an efficient agent for the back-extraction of rhodium and concomitant noble metals (Pd, Ru, Ag). The back-extraction of rhodium proceeds via coordination mechanism, [Rh(tu)6](NO3)3 being the major product. Aqueous 1 mol/L solution of TU ensures stripping of at least 91% rhodium and provides its relative concentrating up to 4 times (time of phase contact is 5 min, temperature 20–35°C). The presence of palladium and other noble metals in extract does not affect the Rh stripping.

The substantial and metrological meaning of the parameters that could be estimated in tensimetric studies was refined taking into account the universal (valid for all reactions) interrelation between the enthalpy (Δ r H ), entropy (Δ r S ), and Gibbs energy (Δ r G ) of vaporization of condensed (liquid or solid) pure substances. Satisfactory linearity of semilogarithmic dependences of the partial pressures ( P A ) of monomolecular saturated vapor components on inverse temperature (1/ T ) was found to be insufficient for drawing conclusions about high-level constancy of Δ r H and the standard (related to P A = 1 atm) entropy Δ r S o . A new more informative approach to the least squares treatment and interpretation of tensimetric data was suggested. The approach was illustrated for the example of the literature data on liquid mercury obtained by the flow method over the temperature range 484–575 K.

The significance and metrological meaning of parameters accessible to regressive estimates from the experimental data on solubility polytherms are refined using corollaries to the universal interrelation between the Gibbs energy, enthalpy, and entropy of dissolution. A standard procedure for processing solubility polytherms is suggested. Its informativeness is illustrated for the example of new metrologically verified data on the polytherm of solubility of ferrocene in pure water.

Appearance of composite bands consisting of two individual bands with different half-widths in the course of resolution of absorption spectra was analyzed.

The data obtained in 2003 and 2004 characterize the quality of water from drinking water sources used by inhabitants of the Ust’-Ordynskii Buryat Autonomous District (BAD), Irkutsk oblast, and Aginskii BAD. In the 20th century, these regions were affected by the technogenic and radiation pollution (as a result of nuclear weapon tests). Analysis of water samples has shown for the majority of the examined sources that the permissible concentrations are exceeded in many parameters of the chemical composition. Permanent use of water from these sources can be one of the health hazards for the local population.

The literature data on the equilibrium constants of formation of HgCl–3 solv and HgCl2–4 solv from HgCl2 solv and Cl–solv in aqueous perchlorate–chloride solutions were generalized. The individual electronic absorption spectrum of the trichloro complex of mercury(II) was obtained for the first time, and the effect of the ionic strength on the spectra of di-, tri-, and tetrachloro complexes of mercury(II) was considered. The previously developed procedures for the resolution of absorption spectra into individual bands were found to be suitable for interpretation of spectral changes experimentally observed for solutions as the result of stepwise complexation. The parameters of the absorption bands in the spectra of chloro complexes of mercury(II) were determined.

The second stage of hydrolysis of the AuCl(4) (aq) species at high acidities was studied spectrophotometrically. Low [Cl(-)] values were maintained with the use of the buffer system of mercury(II) chloro complexes. From our results and independent data on the first stage of aquation and alkali hydrolysis of AuCl(4)(-), the equilibrium constant of the reaction AuCl(4)(-) + 2H(2)O reversible arrow AUCl(2)(H(2)O)(OH) + H(+) + 2Cl(-) was estimated: pK = 10.7 +/- 0.2 at mu = 0 and T= 25 degrees C.

The influence of the ionic medium and concentration of halide ions on the spectra of the solutions containing anionic complexes AuX4solv- (X = Cl- or Br-) is studied. Parameters of the individual bands of the ionic complexes in the media studied are obtained. Formation constants of AuBr5 solv2- in 5.0 M NaBr are estimated and used to calculate the spectrum of this complex. The parameters of the individual bands of the tetra- and pentabromide complexes are compared with one another. For the latter, two strong bands occur in the range 37000-30000 cm(-1), instead of a single band for the tetrabromide complex.

Reactions of niobium tetraiodide with sterically hindered beta-diketones in the presence of diethylamine gave eight-coordinate Nb(IV) complexes Nb(beta-diket)(4). The thermal stability of the complexes at atmospheric pressure and in a vacuum and the nature of the hydrolysis and oxidation products were studied. The possibility of using the complexes as precursors for preparing Nb(IV) oxide layers was examined.