Solubility and Pitzer's ionic parameters in the system H2O-NaCl-MgCl2

The object of this work was to determine Pitzer's ionic parameters, θ and Ψ, for the mixed salt solution H2O-NaCl-MgCl2 at following temperatures: 273.15, 298.15, 356.15 and 378.15 K in ionic strength interval from 7 to 17.5 mol/kg, using Pitzer-Kim's ionic method. The Pitzer's ionic interaction parameters at all temperatures were evaluated on the bases of solubility data for the system H2O-NaCl-MgCl2, and criterion of diffusion equilibrium. The mean ionic activity coefficient of the NaCl in heterogeneous system, in which NaCl(c) was in equilibrium with saturated mixed solution H2O-NaCl-MgCl2, was obtained using solubility data and criterion of diffusion equilibrium. Temperature dependence of the obtained Pitzer's ionic interaction parameters θ and Ψ,in temperature range from 273.15 to 378.15 K, were described by the polynom of the forth and second order, respectively

Osmotic coefficient of the ZnSO4(aq) at T=298.15 K

The osmotic coefficient of ZnSO4(aq) has been measured at T = 298.15 K by the iso-piestic method, in the range of molalities from 1.3 to 3.0 mol . kg(-1), with KCl(aq) as the reference solution. Experimental data of osmotic coefficient were treated to determine the ionic interaction parameters in Pitzer's equation and equation of Clegg-Pitzer-Brimblecombe. These equations were used to calculate the activity coefficient of ZnSO4 at T = 298. 15 K

Osmotic and activity coefficients of {yK(2)SO(4)+(1-y)Mg(NO3)(2)}(aq) at the temperature T = 298.15 K

'The osmotic coefficients of the mixed electrolyte solution {yK(2)SO(4) + (1 - y)Mg(NO3)(2)}(aq) have been measured by the isopiestic method, at the temperature T = 298.15 K. The activity coefficients of K2SO4 and Mg(NO3)(2) were calculated by Scatchard's neutral-electrolyte method and by Fitter and Kim's treatment for mixed electrolyte solutions. The results are used for calculation of the excess Gibbs energy as a function of ionic strength and ionic-strength fraction of K2SO4, and also as a test of Zdanovskii's rule of linearity

Osmotic and activity coefficients of {yKCl+(1-y)MgCl2}(aq) at T=298.15 k

Isopiestic vapor-pressure measurements were made at the temperature 298.15 K for aqueous KCl + MgCl2 solutions using KCl(aq) as the reference standard. The measurements for these ternary solutions were made at KCl ionic strength fractions of y=0.0, 0.1989, 0.3996, 0.5993, 0.7925 and 1.0 (with two additional sets at y=0.0, 0.2021, 0.3998, 0.6125, 0.8209 and 1.0) for the ionic strength range from 0.4014 to 6.2790 mol center dot kg(-1). Our results, and those from two previous isopiestic studies, were combined and used with previously determined parameters for KCl(aq) and those determined here for MgCl2(aq) to evaluate mixing parameters for the Clegg-Pitzer-Brimblecombe model. These combined data were also used to determine the mixing parameters of the Scatchard model. Both sets of model parameters are valid for ionic strengths of lt = 12.8 mol center dot kg(-1), where higher-order electrostatic effects have been included in the Clegg-Pitzer-Brimblecombe mixture model. The activity coefficients for KCl and MgCl2 were calculated from these models and the results for KCl were compared to experimental data from Emf measurements. The Scatchard model interaction parameters were used for calculation of the excess Gibbs energy as a function of the ionic strength and ionic strength fraction of KCl. The Zdanovskii-Robinson-Stokes rule of linearity for mixing of isopiestic solutions was tested

Matematički model za eksergiju u sistemu NaCl-H2O

In this work mathematical models for the exergy and relative enthalpy of the water solution of sodium-chloride and the pure crystalline sodium-chloride where derived. The environment was defined with the temperature 20 °C, pressure 101,325 kPa and with liquid water and crystalline sodium-chloride, both having at the defined environmental conditions the value of exergy equal zero. The obtained mathematical model is valid in the temperature interval from 0 to 170°C and for the all compositions of solution, until to saturation. The derived mathematical model for the exergy is based on the Pitzer's ion interaction equation which satisfactory represents the dependence of the osmotic coefficient and the mean ionic activity coefficient on the composition of solution. The calculated values of exergy using the mathematical model were compared with the appropriate diagram for the exergy constructed using the table values of activity coefficients, osmotic coefficients and partial molar enthalpies.Izveden je matematički model za eksergiju i relativnu entalpiju vodenih rastvora natrijum-hlorida i čistog kristalnog natrijum-hlorida. Uzeto je da je okolina na temperaturi 20°C i pritisku 101,325 kPa i da je čine voda u tečnom i natrijum-hlorid u čvrstom agregatnom stanju, koji pod ovim uslovima imaju vrednost eksergije nula. Model se zasniva na Pitzer-ovoj jednačini jon interakcionog tipa za zavisnost koeficijenta aktivnosti i osmotskog koeficijenta od sastava rastvora

Influence of Hydrolysis on the Osmotic Coefficients of the System {yZnCl(2) + (1-y)ZnSO4}(aq) at Temperature 298.15 K

Isopiestic vapor pressure measurements were made for {yZnCl(2) + (1 - y)ZnSO4}(aq) solutions with ZnCl2 ionic strength fractions of y = (0.2640, 0.5042, 0.7533, and 1) at the temperature 298.15 K, using KCl(aq) as the reference standard. To investigate the influence of hydrolysis on the osmotic coefficients of {yZnCl(2) + (1 - y)ZnSO4}(aq), the ZnCl2(aq) stock solution was prepared without acidification and supression of hydrolysis. Thus obtained osmotic coefficients of the system {yZnCl(2) + (1 - y)ZnSO4}(aq) at the temperature 298.15 K were compared with the previously published results of the isopiestic measurements for the same system with ZnCl2(aq) stock solution that was acidified to avoid precipitation of zinc hydroxide or a hydrous oxy-chloride or hydroxy-chloride, upon dilution. This way the effects of hydrolysis on the osmotic coefficient values for the system {yZnCl(2) + (1 - y)ZnSO4}(aq) could be compared and analyzed

Osmotic coefficient of the ZnCl2(aq) at T=298.15 K

The osmotic coefficient of ZnCl2(aq) has been measured at T = 298.15 K by the isopiestic method over the range of molalities from (0.4 to 2.4) mol . kg(-1) with KCl(aq) as the reference solution. The available literature data on the osmotic coefficient of ZnCl2(aq) at T = 298.15 K, and new experimental data were treated by the Clegg-Pitzer-Brimblecombe equation and the extended Pitzer's equation. These equations were used to calculate the activity coefficient of ZnCl2 at T = 298.15 K. The formation of the ZnCl+ complex has been taken into account by means of the Clegg-Pitzer-Brimblecombe equation

Osmotic and activity coefficients of {yNaH(2)PO(4)+(1-y)Na2SO4}(aq) at the temperature 298.15 K

The osmotic coefficients of the mixed electrolyte solution {yNaH(2)PO(4) + (1 - y)Na2SO4}(aq) have been measured by the isopiestic method, at the temperature T = 298.15 K. The activity coefficients of NaH2PO4 and Na2SO4 were calculated by Scatchard's neutral-electrolyte method and by Pitzer and Kim's treatment for mixed-electrolyte solutions. The Scatchard interaction parameters are used for calculation of the excess Gibbs energy as a function of ionic strength and ionic-strength fraction of NaH2PO4. Also, the Zdanovskii's rule of linearity is tested

Low temperature processes during the synthesis of lanthanum lead borosilicate glasses

Low temperature processes during the synthesis of PbO-B 2 O 3 -SiO 2 -La 2 O 3 glasses were studied by thermal analysis of the batch mixture of glasses and X-ray powder diffraction analysis of samples that crystallized during invesrtigations of the crystallization ability of the synthesized glasses. The obtained results and available thermodynamic data indicate the formation of PbO·B 2 O 3 , PbO·2B 2 O 3 and La 2 O 3 ·B 2 O 3 ·SiO 2 in the temperature interval 400-700°C