Densities and apparent molar volumes for aqueous solutions of HNO3−UO2(NO3)2 at 298.15 K

In order to obtain the exact information of atomic number density in the ternary system of HNO₃−UO₂(NO₃)₂−H₂O, the densities were measured with an Anton-Paar DMA60/602 digital density meter thermostated at 298.15±0.01 K. The apparent molal volumes for the systems were calculated from the experimental data. The present measured apparent molar volumes have been fitted to the Pitzer ion-interaction model, which provides an adequate representation of the experimental data for mixed aqueous electrolyte solutions up to 6.2 mol/kg ionic strength. This fit yields θ ^V , and ψ ^V , which are the first derivatives with respect to pressure of the mixing interaction parameters for the excess free energy. With the mixing parameters θ ^V , and ψ ^V , the densities and apparent molar volumes of the ternary system studied in this work can be calculated with good accuracy, as shown by the standard deviations.     

Apparent and standard molar volumes and heat capacities of aqueous Ni(ClO4)2 from 25 to 85°C

Apparent molar heat capacities and volumes of aqueous Ni(C10₄)₂ were measured from 25 to 85°C over a concentration range of 0.02 to 0.8 mol-kg^-1 using a Picker flow microcalorimeter and a Picker vibrating-tube densimeter. An extended Debye-Hückel equation was fitted to the experimental data to obtain expressions for the apparent molar properties as functions of ionic strength for Ni(ClO₄)₂(aq). The standard-state partial molar properties for Ni(C10₄)₂(aq) in the temperature range 25 to 85°C were obtained and can be expressed by empirical equations as 97787 and withT in K. The standard partial molar heat capacities and volumes for Ni²⁺ (aq) from 25 to 86°C were obtained by using the additivity rule and data for ClO^- ₄(aq) in the literature. These values were extrapolated to 300°C by employing the Helgeson-Kirkham-Flower (HKF) equations, amended to include a standard-state correction term.     

Temperature dependence of apparent molar volumes and viscosity B-coefficients of amino acids in aqueous potassium thiocyanate solutions from 15 to 35°C

Precise density and viscosity data at 15, 25 and 35°C for solutions of glycine, DL-alanine, L-threonine, -alanine, -aminobutyric acid and -aminocaproic acid in water and in (1m, 3m, 5m) aqueous potassium thiocyanate were measured and the limiting apparent molar volumes V ^o and the B-coefficients calculated. The V ^o and B values were split into the contributions from the NH ₃ ⁺ ,COO^– and CH₂ groups. These data are rationalized on the basis of hydrophillic and hydrophobic interactions between the various groups present in these solutions.Abstracted from the Ph.D Thesis of R. K. Goyal, University of Delhi, 1990.     

Apparent molar volumes of aqueous calcium chloride to 250°C, 400 bars,and from molalities of 0.242 to 6.150

Relative densities of CaCl ₂ (aq) with 0.22ml(mol-kg^–1)6.150 were measured with vibrating- tube densimeters between 25 and 250°C and near 70 and 400 bars. Apparent molar volumes V calculated from the measured density differences were represented with the Pitzer ioninteraction treatment, with appropriate expressions chosen for the temperature and pressure dependence of the virial coefficients of the model. It was found that the partial molar volume at infinite dilution V ^o , and the second and third virial coefficients B ^V and C ^V , were necessary to represent V near the estimated experimental uncertainty. The ionic-strength dependent ^(1)v term in the B ^V coefficient was included in the fit. The representation for V has been integrated with respect to pressure to establish the pressure dependence of excess free energies over the temperature range studied. The volumetric data indicate that the logarithm of the mean ionic activity coefficient, ln ±(CaCl ₂ ), increases by a maximum of 0.3 at 400 bars, 250°C, and 6 mol-kg^–1 as compared with its value at saturation pressure.     

Titration of Potentiometric NH4VO3, KH2PO4, K2HPO4, and their Mixture in Molten NaNO3 at 350°C Using a Novel Solid‐State Glass/TiO2 pH Indicator Electrode

A solid‐state Glass/TiO₂ electrode was fabricated using a transparent conductive titanium oxide film on a glass substrate. The coating of the glass substrate was achieved by a novel simple chemical vapor deposition (CVD) procedure. This electrode can be used as an indicator electrode in potentiometric acid‐base titration. This electrode behaves reversibly and responds to the oxide ion concentration in molten nitrate. NH₄VO₃, KH₂PO₄, K₂HPO₄, and their mixture were titrated with Na₂O₂ at 350°C using the glass/TiO₂ electrode in molten NaNO₃.     

Thermochemical investigations of the systems KCl−KBr−H2O,K2SO4−(NH4)2SO4−H2O and KNO3−NH4NO3−H2O at 298.15 K

For the equilibrium solid phases occurring in the systems: KCl?KBr?H₂O, K₂SO₄?(NH₄)₂SO₄?H₂O and KNO₃?NH₄NO₃?H₂O, the concentration dependencies of differential solution enthalpies, Δ_sol H ₂ for several crystallization paths, were measured. The limiting differential solution enthalpies, Δ_sol H ₂ ⁰ , were determined by extrapolation of the above dependencies to the ionic strength,I _m ⁰ , corresponding to the appropriate binary solutions. For KCl?KBr?H₂O system only, the clear dependence between Δ_sol H ₂ ⁰ andI _m ⁰ values was found and discussed.     

Phase equilibria of the Na,K,Mg,Ca//SO4,Cl-H2O system at 50°C in the crystallization range of glaserite 3K2SO4·Na2SO4

Phase equilibria of the Na,K,Mg,Na,K,Mg,Ca//SO₄,Cl-H₂O system are studied at 50°C via translation in the crystallization range of glaserite (3K₂SO₄ · Na₂SO₄). It is found that glaserite as the equilibrium phase of the investigated system at 50°C participates in the formation of 21 invariant points, 21 monovariant curves, and 34 divariant fields. A fragment of the phase equilibria diagram of the investigated system is constructed in the crystallization range of glaserite.     

Phase equilibria in the Na,Ca‖SO4,CO3,F-H2O at 0°C

Phase equilibria in the Na,Ca‖SO₄,CO₃,F-H₂O system at 0°C were studied using the translation method. Seven invariant points, 18 monovariant curves, and 17 divariant fields were found to exist. A looped phase diagram (phase complex) of the title system was constructed.     

The (p, ρ, T) properties and apparent molar volumes Vϕ of (ZnBr2 + C2H5OH)

The (p, ρ, T) properties and apparent molar volumes V_? of ZnBr₂ in ethanol at temperatures (293.15 to 393.15) K and pressures up to p = 40 MPa are reported. The measurements were made with a recently developed vibration-tube densimeter. The system was calibrated using double-distilled water, methanol, ethanol, and aqueous NaCl solutions. The experiments were carried out at molalities of m = (0.05681, 0.16958, 0.30426, 0.43835, 0.93055, 1.49016, and 1.88723) mol · kg^?1 using zinc bromide. An empirical correlation for the density of (ZnBr₂ + C₂H₅OH) with pressure, temperature, and molality has been derived. This equation of state was used to calculate other volumetric properties such as isothermal compressibility, isobaric thermal expansibility, the differences in specific heat capacities at constant pressures and volumes, apparent molar volumes of ZnBr₂ in ethanol, and partial molar volumes of both components.     

Investigations of the thermal stability and phase transformations in the system marocco phosphorite—(NH4)3H(SO4)2.NH4HSO4

Different physical chemical methods were used to study the thermochemical processes in a system involving a natural phosphate and complex acid salts of ammonium sulphate. The products of decomposition of the double ammonium salt and the products of their interactions with the phosphate were identified. The formation of ammonium and calcium polyphosphates and the disproportionation of P₃O ₁₀ ^5? and P₂O ₇ ^4? to PO ₄ ^3? and PO ₃ ^? were found to depend on the circumstances of the thermal interactions.     

Synthesis,crystal structure of Gd(H2O)(C2O4)2 · NH4 and of La(C2O4)2 · NH4. Characterization of the Ln(H2O)(C2O4)2 · NH4 with Ln=Eu…Yb

Single crystals of two lanthanide complexes, presenting similar formula Ln(H₂O)_x(C₂O₄)₂ · NH₄ with Ln=La, x=0 and Ln=Gd, x=1, have been prepared, in closed system at 200 °C. The gadolinium complex is bi-dimensional. A layer is built by the packing of the basic unit, [Gd(C₂O₄)]₄. The gadolinium atoms are related only by bischelating oxalate ligands, the ammonium ion and the water molecule (bound to the gadolinium atom) are localized into the interlayer space. The lanthanum complex is tri-dimensional. The basic building unit remains approximately the same and the packing of these units form a layer. However, within these units, the lanthanum atoms are related by either an oxalate ligand or an edge. Moreover, an oxalate ligand assumes the connection between the layers. The ammonium ion is localized into two sets of intersecting channels. Pure phase of the gadolinium complex has been prepared at 100 °C and extended to some lanthanide elements, Eu…Yb. As the size of the lanthanide ionic radius is decreasing, it is noticeable that the a unit–cell constant follows an expansion pattern while the others two follow an usual contraction one. The thermal behavior of this family shows that the anhydrous compounds are obtained and that some water molecule is sorbed during the cooling. Thus, the anhydrous compounds present a relatively open-framework with some small micropores.     

Potentiometric Titration of Na2HAsO4, NaPO3, Na4P2O7, and their Binary Mixtures in NaNO3 Melt at 350°C Using a Novel Solid State Glass/TiO2 as pH Indicator Electrode

A solid‐state glass/TiO₂ electrode was fabricated using a transparent conductive titanium oxide film on a glass substrate. The coating of the glass substrate was achieved by a novel simple chemical vapor deposition (CVD) procedure. This electrode can be used as an indicator electrode in potentiometric acid‐base titration. This electrode behaves reversibly and responds to the oxide ion concentration in molten NaNO₃ · Na₂HAsO₄, NaPO₃, Na₄P₂O₇, and their binary mixtures were potentiometrically titrated with Na₂O₂ as titrants in molten NaNO₃ at 350°C, using the above mentioned indicator electrode.     

Synthesis and Crystal Structure of Copper(I) Chloride π-Complexes with N-Allyl- and N,N'-Diallylpiperazinium Dichlorides: [C3H5NH(CH2)4NH2]Cu2Cl4and [C3H5NH(CH2)4NHC3H5]0.5CuCl2

The crystals of copper(I) π-complexes with N-allyl piperazine derivatives, [C₃H₅NH(CH₂)₄NH₂]Cu₂Cl₄(I) and [C₃H₅NH(CH₂)₄NHC₃H₅]_0.5CuCl₂(II), were prepared by alternating-current electrochemical synthesis. X-ray diffraction study showed that compounds Iand IIcrystallize in the monoclinic system: for I, space group P2₁/a, a= 10.254(4) Å, b= 12.306(4) Å, c= 10.656(4) Å, γ = 98.83(3)°, V= 1329(2) ų, Z= 4, R= 0.0457 for 1334 independent reflections; for II, space group P2₁/n, a= 10.187(2) Å, b= 7.283(2) Å, c= 10.480(3) Å, γ = 100.72(2)°, V= 764.0(6) ų, Z= 4, R= 0.0371 for 1025 independent reflections. The structure of Iis composed of {Cu₂Cl₄(C₇H₁₆N₂)}₂dimers linked by fairly strong (N)H···Cl hydrogen bonds (2.35(4) Å). The structure of IIconsists of centrosymmetrical dimeric Cu₂Cl₄ ^2–anions, whose copper atoms coordinate the allyl groups of different centrosymmetrical organic cations. The dimer–ligand chains are stretched along the [ $ {11} $ 0] direction and are joined by hydrogen contacts (N)H···Cl (2.62(4) Å).     

Crystal structure,DSC and Raman studies in CH3C6H4NH(CH3)2·SbCl4

The salt para methyl phenyl dimethyl ammonium tetrachloroantimonate (III) crystallizes in the monoclinic system with space group Cc. The unit cell dimensions are: a=13.780(1) Å, b=14.943(2) Å, c=8.192(1) Å, β=113.39(1)°, with Z=4. The structure consists of ammonium cations and polynuclear anions in which distorted SbCl₅ square pyramids sharing a common Cl atom are held together in infinite chains parallel to the c axis. These chains are themselves interconnected by means of the NH⋯Cl hydrogen bonds. Differential scanning calorimetry study was carried out. The Raman of polycrystalline samples have been recorded at different temperatures between 77 and 300 K. A low-temperature phase transition at 230 K of order-disorder type was found.     

Structure,synthesis, and thermal properties of trans-[Ru(NO)(NH3)4(SO4)]NO3·H2O

In treatment of trans-[Ru(NO)(NH₃)₄(OH)]Cl₂ with concentrated sulfuric acid on heating trans-[Ru(NO)(NH₃)₄(SO₄)](HSO₄)·H₂O (I) is obtained with a yield close to quantitative. In the interaction of the saturated solution of I with a saturated NaNO₃ solution a trans-[Ru(NO)(NH₃)₄(SO₄)]NO₃·H₂O (II) precipitate forms whose structure is determined by single crystal XRD: space group P2₁2₁2₁, a = 6.8406(3) Å, b = 12.6581(5) Å, c = 13.3291(5) Å. A monodentately coordinated sulfate ion is in the trans-position to the nitroso group. Compound II is characterized by IR spectroscopy, powder XRD, and diffuse reflectance spectroscopy. The process of its thermolysis is studied; by differential scanning calorimetry the thermal effect of the dehydration reaction occurring on heating to 120°C (ΔH = 58.9 ± 1.5 kJ/mol) is estimated. The final product of the thermolysis of II is a mixture of Ru and RuO₂.     

Synthesis,open-framework structure and thermal behaviour of ammonium tin oxalate,Sn2(NH4)2(C2O4)3·3H2O

A new mixed ammonium tin oxalate trihydrate, Sn₂(NH₄)₂(C₂O₄)₃·3H₂O, has been prepared from evaporation of a solution of tin and ammonium oxalates. Its crystal structure has been solved from single-crystal diffraction data. The symmetry is orthorhombic, space group Pnma (No. 62), cell dimensions a=15.1821(5) Å, b=11.7506(2) Å, c=10.8342(3) Å, and Z=4. The structure consists of macroanionic layers built from [Sn(C₂O₄)₃]^2– groups. The SnO₆ polyhedron can be described as a pseudo pentagonal bipyramid, with the lone pair of electrons presumably occupying one apex. The resulting framework displays holes in which the water molecules and ammonium groups are located. The thermal behaviour of the mixed ammonium tin oxalate has been investigated with temperature-dependent X-ray powder diffraction and conventional thermal analysis. The degradation process has been completely explained, as well as that of oxammite, a phase always obtained in the preparations. The thermal decomposition of oxammite leads to (NH₄)₂C₂O₄ and a new acid salt, NH₄HC₂O₄. The mixed ammonium tin oxalate decomposes successively into the amorphous compounds, Sn₂(NH₄)₂(C₂O₄)₃·H₂O and Sn₂(NH₄)₂(C₂O₄)₃, SnC₂O₄ and, finally, cassiterite SnO₂.     

The Activity Coefficients of HCl in HCl–Na2SO4 Solutions from 0 to 50°C and Ionic Strengths Up to 6 Molal

The electromotive force of HCl−Na₂SO₄ solutions has been determined from 5 to 50°C and ionic strengths from 0.5 to 6m with a Harned type cell The results have been used to determine the activity coefficient of HCl in the mixtures. The activity coefficiencts have been analyzed with the Pitzer equations to account for the ionic interactions. The measurements were used to determine interaction coefficients (β⁰, β¹) for NaHSO₄ solutions from 5 to 50°C. The model represents the mean activity coefficients HCl in the mixtures to ±0.005 over the entire temperature and concentration range of the measurements. The results have been combined with literature data to provide parameters that are valid from 0 to 250°C for NaHSO₄ solutions.     

Macro-, Micro-, Nano- and Crystal Structures of a Homodinuclear Complex [NH3（ CH2）3NH3]2{Na2[（C6H4O2）2]（C6H4O2H）2}

A homodinuclear complex （NH3CH2CH2CH2NH3）2 {Na2[（C6H4O2）2] （C6H4O2H）2} （1） has been synthesized by a solution-based self-assembly route. It crystallized in monoclinic system with space group P21/c. Every sodium ion coordinates in a tetragonal prism fashion with two O atoms of a terminal chelating catecholate ligand and three O atoms from two bridging catecholate ligands. Two neighboring NaO5 tetragonal prisms are edge-shared and centrosymmetric with regard to the inversion center to form a binuclear cluster {Na2[（C6H4O2）2]（C6H4OOH）2}^4- anion. The complex anions were aligned parallelly by n-n interaction and linked with the protonated 1,3-propylenediamine through hydrogen bonds which were assembled into a multi-lamellar structure with channels. The crystal exhibits rectangular geometry with an interior triangle hollow structure under optical microscopy. And the scanning electron microscopy （SEM） indicates that the wall of the tubes shows multi-lamella morphologies. Further, the transmission electron microscopy （TEM） reveals that the crystal is composed of multi-lamellar nano-tubes with diameters less than 100 nm. The molecular structure of the complex was compared with that of its isomer complex 2.     

Influence of MgHPO4·3H2O and Mg3(PO4)2·8H2O on Thermal Reactions (20°-1000°C) in Solid Solutions with Al2(SO4)3·16H2O

Abstract

The following binary systems were studied: AI₂(SO₄)₃·16H₂0 - MgHPO₄·3H₂O and AI₂(SO₄)₃·16H₂O - Mg₃(P0₄)₂·8H₂0.