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  • Pitzer's equations  (3)
  • Carbonic acid  (2)
  • Densities  (2)
  • Springer  (6)
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  • Springer  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of solution chemistry 28 (1999), S. 849-864 
    ISSN: 1572-8927
    Keywords: Apparent molar heat capacities ; partial molar heat capacities ; Pitzer's equations ; lanthanide elements ; transition metals ; alkali metal sulfates ; magnesium sulfate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Apparent molar heat capacities C p,φ for 71 rare earth chlorides, nitrates, and perchlorates, alkaline earth and transition metal chlorides, nitrates, and perchlorates, and alkali metal carbonates and sulfates have been fitted to the Pitzer equation for heat capacities. The apparent molar heat capacities at infinite dilution $$C_{{\text{p,}}\Phi }^{\text{o}} $$ (equal to the standard partial molar heat capacity, $$\overline C _{{\text{p,2}}}^{\text{o}} $$ ) were used to evaluate a set of “best” ionic heat capacities, from which improved values of $$C_{{\text{p,}}\Phi }^{\text{o}} $$ for the electrolytes were calculated. These were then used in the Pitzer equation to reevaluate the higher Pitzer coefficients. The Pitzer coefficients so evaluated can express, in most cases, the behavior of C p,φ within experimental error from infinite dilution to the upper limit of the data. Ionic heat capacities have been correlated with the absolute entropies of the ions by statistically assigning the ionic heat capacities to obtain the best linear fit.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of solution chemistry 11 (1982), S. 447-456 
    ISSN: 1572-8927
    Keywords: Carbonic acid ; concentrated aqueous solutions ; ionization constants ; Pitzer's equations ; activity coefficients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The stoichiometric pK 1 * and pK 2 * for the ionization of carbonic acid has been determined from emf measurements in NaCl soluions to 6.0m at 25°C. Our results at low concentrations are in good agreement with the results of Harned and Bonner, of Dyrssen and Hansson and of Roy et al. The calculated values of pK 1 * using Pitzer's equations agree with the measured values to ±0.01 pK units provided higher order terms are used. It was necessary to use a triplet interaction parameter (ψ) and higher order electrostatic terms (Eθ) to calculate reliable values of pK 2 * (±0.03 pK units) over the entire concentration range. These results demonstrate the reliability of the Pitzer equations to estimate activity coefficients in concentrated salt solutions.
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  • 3
    ISSN: 1572-8927
    Keywords: Densities ; partial molal volumes ; KCl ; K2SO4 ; Pitzer theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The densities of KCl and K2SO4 were measured from dilute solutions to saturation from 5 to 95°C. The data were combined with literature data to produce density and apparent molal volume, Vφ, equations from 0 to 100°C and to saturation. The standard deviations of the density equations were 30×10−6 g-cm−3 and 32×10−6 g-cm−3, respectively, for KCl and K2SO4. Pitzer equations were used to fit the Vφ data. The resulting infinite dilute partial molal volumes, Vo, were in reasonable agreement with literature data. The densities of the mixtures of the six combinations of the salts KCL, K2SO4 NaCl and Na2SO4 were measured at I=2.0 and t=5, 25, 55 and 95°C. The resulting volumes of mixing were fitted to equations of the form $$\Delta V_m = y(1 - y)I^2 [\nu _0 + \nu _1 (1 - 2y)]$$ wherev 0 andv 1 are interaction parameters. The cross square rule is valid over the entire temperature range although the deviations are larger at higher temperatures. Pitzer θ NaK v and $$\theta _{ClSO_4 }^v $$ parameters were determined from the common ion mixtures. The values of θ NaK v were small and not strongly dependent upon temperature. The values of $$\theta _{ClSO_4 }^v $$ were also small and changed considerably with temperature.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of solution chemistry 12 (1983), S. 401-412 
    ISSN: 1572-8927
    Keywords: Carbonic acid ; ionization ; Pitzer parameters ; weak acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The stoichiometric pK2 * and pK2 * for the ionization of carbonic acid has been determined from emf measurements in NaCl solutions with small amounts of MgCl2 from I=0.5 to 6.0 molal at 25°C. Our results at low ionic strengths (I=0.7) are in agreement with the measurements of Dyrssen and Hansson and Pytkowicz and Hawley. Our results have been analyzed using the ion pairing model and Pitzer's specific interaction equations. From the values of pK1 *, we have determined the Pitzer parameters β0[Mg (HCO3)2] = 0.0193 and β1[Mg (HCO3)2] = 0.0193 which reproduces the pK1 * results to ±0.01. The values of pK2 * were used to determine β0(MgCO3) = 2.833, β1(MgCO3) = -15.069, β2(MgCO3) = -204.90 and Cϕ (MgCO3)=−0.970 which reproduces the pK2 *′ s to ±0.02. The pK2 * results could be reproduced to the same precision with fewer parameters using the ion pairing model [pK(MgCO3)=3.00 and log γ (MgCO3)=0.0560 I].
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  • 5
    ISSN: 1572-8927
    Keywords: Densities ; partial molal volumes ; NaCl ; Na2SO4 ; MgCl2 ; MgSO4 ; Pitzer theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The densities of the major sea salts (NaCl, Na2SO4, MgCl2, and MgSO4) have been measured from 25 to 95°C and to saturation. These results have been combined with literature data and fitted to equations of the form $$\Delta d = Am{\text{ }} + {\text{ }}Bm^{3/2} {\text{ }} + {\text{ }}Cm^2 {\text{ }} + {\text{ }}Dm^{5/2} $$ where Δd=d−do (do is the density of water) and A, B, and C, etc., are polynomial functions of temperature. The standard deviations of the fits were better than ±50×10−6 g-cm−3 for all the salts from 0 to 95°C and to saturation. The apparent molal volumes Vϕ of the salts have been fitted to the equations of Pitzer. The infinite dilution values of Vϕ were in good agreement with literature data, provided the results were not overfit. The large deviations of Vϕ for MgSO4 from additivity as a function of concentration were attributed to the formation of MgSO4 ion pairs.
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  • 6
    ISSN: 1572-8927
    Keywords: Transition metals ; CoCl2 ; CuCl2 ; MnCl2 ; enthalpy of mixing ; Pitzer's equations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Enthalpies of mixing (Δm H) aqueous solutions of CoCl2, CuCl2, and MnCl2 with NaCl solutions were measured at constant ionic strengths of 0.5, 1.0, and 3.0 molal at 25°C. The excess enthalpy equations of Pitzer were then fit to the resulting Δm H data. The resulting parameters are the temperature derivatives of the activity coefficient mixing parameters in the Pitzer system. The heat of mixing data for CoCl2 and CuCl2 were in agreement with earlier isomolal results by other workers.
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