Solution thermodynamics of first-row transition elements. 4. Apparent molal volumes of aqueous ZnSO4 and CuSO4 solutions from 15 to 55°C

The apparent molal volumes of ZnSO ₄ and CuSO ₄ have been determined from density data over the temperature range 15–55°C and concentration range 0–15 molal. The volume data have been fitted to the Pitzer formalism over the entire temperature and concentration range. The volume changes for the formation of ZnSO ₄ and CuSO ₄ ion pairs have been estimated over the temperature range covered and the partial molal volumes of ZnSO ₄ and CuSO ₄ ion pairs have been derived. The results were used to explain the hydration structure of the ion pair. UV spectral effects accompanying a change of temperature in the 15–65°C range in CuSO ₄ solution indicate direct coordination of sulfate anion to the cupric cation. The process is favored by an increase in temperature.     

Representation of Electrical Conductances for Polyvalent Electrolytes by the Quint-Viallard Conductivity Equation. Part 1. Symmetrical 2:2 Type Electrolytes. Dilute Aqueous Solutions of Alkaline Earth Metal Sulfates and Transition Metal Sulfates

Literature values of the electrical conductivities of dilute aqueous solutions of alkaline metal sulfates (BeSO₄, MgSO₄, CaSO₄, SrSO₄) and of transition metal sulfates (MnSO₄, FeSO₄, CoSO₄, NiSO₄, CuSO₄, ZnSO₄, CdSO₄) were reexamined within the framework of the Quint-Viallard conductivity equations in order to obtain a uniform representation of conductivities. It was observed that the limiting conductances of electrolytes at infinite dilution are very similar irrespective of the applied conductivity equation, whereas the derived ion association equilibrium constants vary considerably. The ion association equilibrium constants are therefore of doubtful physical value and should be treated rather as just fitting parameters.     

Enthalpies of Dilution of Some Aqueous Transition Metal Sulfate Solutions at 25°C

Enthalpies of dilution of aqueous solutions of the transition metal sulfates CoSO₄, MnSO₄, and NiSO₄, were measured from 1.5 to 0.2 mol-kg^–1 at 25°C. The apparent molal enthalpy equations of Pitzer were fit to the resulting data and the parameters for these equations presented.     

Untersuchungen zur Kinetik der thermischen Dissoziation von Nickel-, Kupfer- und Zinksulfat

The rates of decomposition and the energies of activation were determined for the thermal dissociation of NiSO₄, CuSO₄, Cu₂(SO₄)O, ZnSO₄and Zn₃(SO₄)₂O. Linear, parabolic and logarithmic rate laws were found. Kinetics are largely determined by the rate of energy transfer. The reasons for the formation of basic sulfate intermediates are discussed.     

Ion Association and Hydration in Aqueous Solutions of Nickel(II) and Cobalt(II) Sulfate

Aqueous solutions of nickel(II) and cobalt(II) sulfate have been investigated at 25 ^∘C by dielectric relaxation spectroscopy (DRS) over a wide range of frequencies (0.2 ≤ ν (GHz) ≤ 89) and salt concentrations (0.025 ≤ c(mol-L⁻¹) ≤ 1.4). The spectra indicate, as for MgSO₄(aq) studied previously, the simultaneous presence of double solvent-separated, solvent-shared and contact ion pairs in both NiSO₄(aq) and CoSO₄(aq). The stepwise formation constants for each ion-pair type and the overall association constant, obtained from the data are in good agreement with ultrasonic relaxation and other estimates. The DR spectra at higher concentrations (c ≥ 0.5 mol-L⁻¹) suggest the existence of a nonlinear triple ion M₂SO₄²⁺(aq). Consistent with the very strong hydration of the salts, which have ‘effective’ hydration numbers approaching 27 at infinite dilution, there are no significant differences in any of the relaxation or thermodynamic parameters for NiSO₄(aq) and CoSO₄(aq), except that the triple ion appears to be somewhat more stable for the latter.     

Divalent sulfate ion pairs in aqueous solutions at pressures up to 2000 atm

Electrical conductance measurements have been made at various temperatures and at concentrations from ca. 0.00005 to ca. 0.01M in aqueous solutions of MgSO₄, CaSO₄, CoSO₄ and NiSO₄ at pressures up to 2000 atm. The data have been analyzed with the Fernandez-Prini modification of the Fuoss-Hsia conductance equation to obtain the molal dissociation constants K _m at each pressure. The results for V^°, obtained from the pressure dependence ofK _m,are compared with other experimental data and with values calculated from acoustically derived multistate dissociation models.     

Study of transition temperature through mixed crystal formation,IV

The study of homogeneous distribution coefficients in determining the transition temperatures of isomorphologically analogous components and in predicting the existences of some new unstable compounds has been carried out in detail with special references to vitriols of nickel, manganese, zinc, copper and magnesium. In the course of the investigation with NiSO₄·7H₂O as host and⁵⁴Mn as guest, the transition temperature of orthorhombic NiSO₄·7H₂O was shown to be 26.5 °C, and with orthorhombic ZnSO₄·7H₂O and MgSO₄·7H₂O as host and copper sulphate as guest, the limits of existences of orthorhombic CuSO₄·7H₂O and newly predicted CuSO₄·6H₂O were found to be 13.5° to 44 °C and 44° to 51 °C, respectively. In addition, the transition temperatures of orthorhombic MnSO₄·7H₂O (10 °C), stable NiSO₄·7H₂O (30.5±5 °C) and orthorhombic ZnSO₄·7H₂O (39 °C) were verified. The new method of approach is very simple, reproducible and easily adaptable.     

The catalytic role of transition metal salts on supercritical water oxidation of phenol and chlorophenols in a titanium reactor

The oxidation of phenol and some chlorophenols by molecular oxygen at a concentration of 1.5x10^-4 mol dm^-3 has been studied in a small static titanium tubular reactor at temperatures of 648, 657, 673 K and a pressures of 22 MPa. The effect of transition metal salts (CuSO₄, VSO₄, FeSO₄, MnSO₄, NiSO₄, CoSO₄), added in small environmentally acceptable amounts as homogeneous catalysts, was also studied, with copper showing a good catalytic effect. This revised version was published online in June 2006 with corrections to the Cover Date.     

Application of NAA in diffusion studies

The diffusion of Mn₂+ ions in CoSO₄ , NiSO₄ and ZnSO₄ containing 1% agar gel as well as that of MnSO₄ in 1% agar gel was studied at 25 °C. The diffusion coefficientsat selected concentrations were determined by the zone diffusion techniqueand by measuring the concentration of diffusing ions using neutron activationanalysis.     

PVT properties of concentrated aqueous electrolytes. II. Compressibilities and apparent molar compressibilities of aqueous NaCl,Na2SO4, MgCl2, and MgSO4 from dilute solution to saturation and from 0 to 50°C

The relative sound velocities (U-U°) of aqueous NaCl, Na₂SO₄, MgCl₂, and MgSO₄ solutions were measured from 0.05m to saturation and from 0 to 45°C. The sound speeds were combined with our earlier work and fitted to a function of molality and temperature to standard deviations within 0.3 m-sec^–1. The adiabatic compressibilities, _s, were determined from the sound speeds and used to calculate adiabatic apparent molar compressibilities, K_,s, isothermal compressibilities, , and apparent molar compressibilities, K, were determined from the adiabatic values using literature data for expansibilities and heat capacities. The values of K have been extrapolated to infinite dilution using an extended limiting law. The resulting K⁰ at various temperatures are in reasonable agreement with literature values. The results of this study have been combined with our earlier results to derive a secant bulk modulus equation of state for NaCl, Na₂SO₄, MgCl₂, and MgSO₄ solutions valid from 0 to 50°C and 0 to 1000 bar.     

Water activity,osmotic and activity coefficients of aqueous solutions of Li2SO4, Na2SO4, K2SO4, (NH4)2SO4, MgSO4, MnSO4, NiSO4, CuSO4, and ZnSO4 at T=298.15 K

The water activities for aqueous solutions of Li₂SO₄(aq), Na₂SO₄(aq), K₂SO₄(aq), (NH₄)₂SO₄(aq), and sulphates MgSO₄(aq), MnSO₄(aq), NiSO₄(aq), CuSO₄(aq), and ZnSO₄(aq) were determined experimentally at a temperature of 298.15 K with a hygrometric method, at molalities in the range from 0.1 mol·kg⁻¹ to saturation. The osmotic coefficients are calculated from these results. The coefficients of Pitzer’s model was used to fit the osmotic coefficients for each salt solution. These parameters were used to predict solute activity coefficients for the salts studied.     

The mutual diffusion coefficients of Na2SO4−H2O and MgSO4−H2O at 25°C from Rayleigh interferometry

The volume-fixed mutual diffusion coefficients of Na₂SO₄–H₂O and MgSO₄–H₂O have been measured, from dilute solutions to near saturation, to an accuracy of 0.1–0.2% by free-diffusion Rayleigh interferometry. These results are compared to other available diffusion data for these salts. The diffusion coefficients of Na₂SO₄–H₂O and MgSO₄–H₂O decrease regularly with increasing concentration, while those of many other salts exhibit both a maximum and a minimum as a function of concentration. A few diffusion coefficients have also been measured for KCl–H₂O.Reference to a company or product names does not imply approval or recommendation of the product by the University of California or the U.S. Department of Energy to the exclusion of others that may be suitable.This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the United States Department of Energy, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights.University of Illinois at Urbana-Champaign; tenure served as a participating guest at Lawrence Livermore Laboratory.     

Über die Entstehung ferromagnetischer Gele und einige verwandte Erscheinungen

Zusammenfassung Durch Zerreiben von Na₂SO₄·10 H₂O, MgSO₄·7 H₂O, MnSO₄·5 H₂O, NiSO₄·7 H₂O, CoSO₄-7H₂O, ZnSO₄·7H₂O CuSO₄·5 H₂O, CdSO₄·8— H₂O, HgSO₄ und (UO₂)·SO₄·3 H₂O mit FeCl₃·6 H₂O werden ferromagnetische Gele erhalten. Durch Autoklavbehandlung dieser Gele entstehen Niederschl?ge, die in ihrem Aussehen weder H?matit noch Magnetit ?hnlich erscheinen. Es wird ein Demonstrationsversuch beschrieben, mit dem der Unterschied der magnetischen Eigenschaft von Eisenhydroxyden je nach der Herstellungsart veranschaulicht wird. Die beim Mischen von Ferro- und Ferril?sungen entstehenden Farb?nderungen werden photometrisch gemessen und diskutiert.     

Kinetics of free-surface decomposition of magnesium and barium sulfates analyzed thermogravimetrically by the third-law method

The application of the third-law method to the determination of the E parameters in cases of free-surface decomposition of MgSO₄ and BaSO₄ in vacuum and investigation of the effect of oxygen in reactor atmosphere on the rate of MgSO₄ decomposition allowed to support the dissociative evaporation mechanism of decomposition of these sulfates with releasing of atomic oxygen as one of the primary products. The experimental values of the E parameter for MgSO₄ and BaSO₄ are equal to 335.7±1.7 and 411±4 kJ mol⁻¹. The serious difference in decomposition temperatures in vacuum (about 1000 and 1400 K) and the E parameters for these two sulfates is connected with the difference in transfer of condensation energy of oxides to the reactants. In cases of MgSO₄ and BaSO₄, the values of τ parameter are 0.42 and 0. Dependence of the τ parameter on the ratio of the equivalent pressure to the saturation pressure of corresponding metal oxide has been revealed from a comparison of τ parameters reported in the literature for eight different reactants. This correlation is of prime consideration for understanding of the mechanism of consumption of the condensation energy by the reactant.     

Pulse radiolysis study of trapped electron in MgSO4.7H2O single crystal

The single crystal of MgSO₄.7H₂O is very interesting to study the structure and kinetics of trapped electron in solids, because the hydrated salt has many H₂O molecules in the crystal lattice like water. The pulse radiolysis study of the trapped electrons in MgSO₄.7H₂O single crystal was carried out based on an electron linear accelerator. Two optical absorption peaks of the trapped electron in MgSO₄.7H₂O single crystal were observed: one is at the wavelength of 600 nm with a short lifetime of 81.4 ns; another is at 400 nm with a long lifetime of 1.06 μs. The kinetics of the trapped electron in the crystal was also compared with that in the aqueous solution.     

The speed of sound in mixtures of the major sea salts. A test of Young's rule for adiabatic PVT properties

The relative sound speed of mixtures of aqueous solutions of NaCl–MgSO₄ and MgCl₂–Na₂SO₄ at I=0.1 and 0.5m have been determined at 5, 15, and 25°C and pressures to 1000 bars. The resulting sound speeds, adiabatic and apparent molal compressibilities have been compared to results estimated from binary solutions using an additivity principle — Young's rule. The estimated sound speeds agree with the measured values for the NaCl–MgSO₄ system to ±0.15 m-sec^–1 and for the Na₂SO₄–MgCL₂ system to ±0.20 m-sec^–1. The deviations increase with increasing ionic strength (±0.08 m-sec^–1 at I=0.1 and ±0.25 m-sec^–1 at I=0.5 m).The sound speed of seawater have also been estimated from 0 to 40°C, 0.1 to 0.7 ionic strength and 0 to 1000 bars. The estimates were found to be in good agreement (±0.4 m-sec^–1) with the measured values.These results indicate that reasonable estimates of the adiabatic PVT properties of dilute mixtures of electrolyte solutions can be made using the additivity principle, without excess mixing terms.     

Volumetric and Viscometric Studies on Some Inorganic Electrolytes in Water and in Water-SDS Solution Systems

The apparent molal volumes (φ _v ) of NaCl, NaNO₃, NH₄Cl, CuCl₂, CuSO₄, CoSO₄ and MgSO₄ in water and in water-SDS (Sodium dodecyl sulphate) solutions were determined from density measurements at 308.15, 313.15 and 323.15 K respectively. The limiting apparent molal volume at infinite dilution φ ^o _v which is practically equal to the partial molal volume V ^o ₂) of these electrolytes were found to be higher in water-SDS solution systems than those in water solutions. Viscosity coefficients (A and B) for these systems were also determined by Jones-Dole equation. All these electrolytes, except NH₄Cl exhibit structure making behaviour in water and in water-SDS solutions. Ammonium chloride showed structure breaking properties in water and in 0.01 molar water-SDS solutions. In 0.1 molar SDS solution, it showed structure making behaviour at the temperature range studied. The properties of these electrolytes in water and in water-SDS solution systems have been discussed in terms of the charge, size and hydrogen bonding effect.     

Near infrared study of aqueous lanthanide perchlorates

The near infrared spectra of water in aqueous solutions of La(ClO₄)₃, Pr(ClO₄)₃, Nd(ClO₄)₃, Gd(ClO₄)₃, Er(ClO₄)₃, Yb(ClO₄)₃, Lu(ClO₄)₃, and NaClO₄ have been measured in the concentration range from 0.3 to 2.5 mol-dm^–3, at 25°C. The relative contents of free OH groups in the 1.0, 1.6, and 2.2M solutions have been calculated from extinction coefficients for water at 1160 nm. They increase with increasing salt concentration and are greater in solutions of the lighter lanthanide perchlorates at any fixed molarity. The results are discussed in terms of the stoichiometry and structure of hydrated cations of trivalent lanthanides.     

Visible and ultra-violet absorption spectra of aqueous solutions of transition metal salts affected by a high-voltage pulse electric discharge

The effect of a high-voltage pulse electric discharge (HVPED) on the electron spectra of CuSO₄, Ni(NO₃)₂, NiCl₂, CoSO₄, and Co(NO₃)₂ aqueous solutions is investigated. It is found that the salt system activation by HVPED can change the configurations of electron shells of molecular ions. It is stated that the processes of post-activation structural relaxation of CuSO₄/H₂O solution are rather long-term. It is shown that the character of the HVPED effect on the electron spectra of solutions significantly depends on the solution composition and the intensity of interparticle interactions therein.     

Enthalpy of solution and effect of temperature on activity coefficients in MSO4−H2SO4−H2O system

Results of calorimetric determination of integral enthalpies of solution of some hydrates (monohydrates and heptahydrates) of 3d transition metal sulphates such as FeSO₄, NiSO₄ and MnSO₄ in three-component systems at sulphuric acid concentrations up to 2M are reported. Measured values of integral enthalpies of solution are the basis for calculation of activity coefficient temperature dependences according to Pitzer's model.