23 research outputs found
Phase Behavior of Aqueous Na-K-Mg-Ca-CI-NO3 Mixtures: Isopiestic Measurements and Thermodynamic Modeling
A comprehensive model has been established for calculating thermodynamic properties of multicomponent aqueous systems containing the Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cl{sup -}, and NO{sub 3}{sup -} ions. The thermodynamic framework is based on a previously developed model for mixed-solvent electrolyte solutions. The framework has been designed to reproduce the properties of salt solutions at temperatures ranging from the freezing point to 300 C and concentrations ranging from infinite dilution to the fused salt limit. The model has been parameterized using a combination of an extensive literature database and new isopiestic measurements for thirteen salt mixtures at 140 C. The measurements have been performed using Oak Ridge National Laboratory's (ORNL) previously designed gravimetric isopiestic apparatus, which makes it possible to detect solid phase precipitation. Water activities are reported for mixtures with a fixed ratio of salts as a function of the total apparent salt mole fraction. The isopiestic measurements reported here simultaneously reflect two fundamental properties of the system, i.e., the activity of water as a function of solution concentration and the occurrence of solid-liquid transitions. The thermodynamic model accurately reproduces the new isopiestic data as well as literature data for binary, ternary and higher-order subsystems. Because of its high accuracy in calculating vapor-liquid and solid-liquid equilibria, the model is suitable for studying deliquescence behavior of multicomponent salt systems
Elektrochemische Fluorierung. III. Elektrofluorierung von Olefinen in nichtwäßrigen Lösungsmitteln. Zum Mechanismus des Anodenvorganges
Coronene-Potassium(THF)2(tmeda): X-Ray Structure and MNDO Calculations of a Half-Sandwich Contact Ion Pair as a Model for Potassium(Adsorbate)-Graphite Surface Interactions
Die photometrische Bestimmung des Vanadiums in Hartmetallen, Carbiden und Oxyden der Metalle Wolfram, Mob, Tantal und Titan
Neue Mischoxyde mit Spinellstruktur. (Mit einem kristallchemischen Beitrag zum Problem des Ferro-magnetismus von Fe-haltigen Spinellen)
The [U2F12]2- Anion of Sr[U2F12]
The D2h-symmetric dinuclear complex anion [U2F12]2- of pastel green Sr[U2F12] shows a hitherto unknown structural feature: The coordination polyhedra around the U atoms are edge-linked monocapped trigonal prisms, the UV atoms are therefore seven-coordinated. This leads to a U-U distance of 3.8913(6)Å. A weak UV-UV interaction is observed for the dinuclear [U2F12]2- complex and described by the antiferromagnetic exchange Jexp of circa -29.9cm-1. The crystalline compound can be easily prepared from SrF2 and β-UF5 in anhydrous hydrogen fluoride (aHF) at room temperature. It was studied by means of single crystal X-ray diffraction, IR, Raman and UV/VIS spectroscopy, magnetic measurements, and by molecular as well as by solid-state quantum chemical calculations.Peer reviewe