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  • Pitzer equations  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Thermodynamics of the System HCl + SmCl3 + H2O from 5 to 55°C. Application of Harned's Rule and the Pitzer Formalism (2000)
    Springer
    Journal of solution chemistry 29 (2000), S. 1211-1227 
    Details
    ISSN: 1572-8927
    Keywords: samarium chloride: activity coefficients ; Nernst equation ; Harned's rule ; emf ; Pitzer equations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A comprehensive array of electrochemical cell measurements for the system HCl +SmCl3 + H2O was made from 5 to 55°C using a cell without liquid junction ofthe type:Pt; H2(g, 1 atm)|HCl (m A) + SmCl3 (m B)|AgCl, Ag (A)The present study, unlike previous studies of trivalent ions, are not complicatedby hydrolysis reactions. Measurements of the emf were performed for solutionsat constant total ionic strengths of 0.025, 0.05, 0.1, 0.25, 0.5, 1.0, 1.5, 2.0, 2.5,and 3.0 mol-kg−1. The mean activity coefficients of HCl (γHCl) in the mixtureswere calculated using the Nernst equation. All the experimental emf measurements(about 850) were first treated in terms of the simpler Harned's rule. Harnedinteraction coefficients (αAB and βAB) were calculated. The linear form of Harned'srule is valid for most ionic strengths, but quadratic terms are needed at I = 1.5and 3 mol-kg−1. The Pitzer model was used to evaluate the activity coefficientsusing literature values, β(0), β(1), and C φ, for HCl from 0 to 50°C and 25°C forSmCl3. The effect of temperature on the parameters for SmCl3 has been estimatedusing enthalpy and heat-capacity data. The mixing parameter ΘH,Sm wasdetermined at 25°C. The addition of the ΨH,Sm,Cl coefficient did not improve the fitsignificantly and no temperature dependence was found to be significant. Thevalue of ΘH,Sm = 0.2 ± 0.01 represented the values of γHCl with a standarddeviation of σ = 0.009 over the entire range of temperatures and ionic strength.The use of higher-order electrostatic effects (EΘH,Sm, EΘH,Sm) was included as itgave a better fit of the activity coefficients of HCl.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026484112080
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Activity Coefficients of HCl + GdCl3 + H2O System from 5 to 55°C. Application of Pitzer Formalism (2000)
    Springer
    Journal of solution chemistry 29 (2000), S. 619-631 
    Details
    ISSN: 1572-8927
    Keywords: Hydrochloric acid ; gadolinium chloride ; emf ; Harned's rule ; Pitzer equations ; activity coefficients ; mixtures of electrolytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The emf of the cell $${\text{Pt, H}}_{\text{2}} ({\text{g, 1 atm}})|{\text{HCI(}}m_{\text{A}} {\text{),GdCl}}_{\text{3}} (m_B )|{\text{AgCl, Ag}}$$ without a liquid junction was used to investigate the HCl + GdCl3 + H2O mixedelectrolyte system. The emf of the cell was measured for HCl + GdCl3 + H2Osolutions at ionic strengths of 0.025, 0.05, 0.1, 0.5, 1.0, 1.5, and 2.0 mol-kg−1and at eleven temperatures ranging from 5 to 55°C at 5°C intervals. The meanactivity coefficients for HCl in the mixtures were determined using the Nernstequation. About 793 experimental emf data points were treated by the Harnedequations. Results show that hydrochloric acid follows Harned's rule at all ionicstrengths, but the quadratic term is needed for I = 1.5 mol-kg−1. Theion-interaction treatment of Pitzer was used to evaluate the results. The binary andternary mixing parameters at 25°C were found to be ΘH,Gd = 0.07 ± 0.03 andΨH,Gd,Cl = 0.14 ± 0.03. These values were determined using literature values ofβ(0), β(1), and C ψ for GdCl3 at 25°C and estimates of the effect of temperaturefrom 5 to 55°C using enthalpy and heat capacity data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005129407455
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  • 3
    Electronic Resource
    Electronic Resource
    The Apparent Molal Volume and Compressibility of Seawater Fit to the Pitzer Equations (2000)
    Springer
    Journal of solution chemistry 29 (2000), S. 719-742 
    Details
    ISSN: 1572-8927
    Keywords: Apparent molal volumes ; apparent molar compressibilities ; sea water ; Pitzer equations ; sea salts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The density and compressibility of seawater salt solutions for ionic strengths 0to 0.8 m, temperatures 0–40°C, and applied pressure 0 to 1000 barare fitted tothe Pitzer equations. The apparent molal volumes and compressibilities (Xφ) arefitted to equations of the form $$X_\phi = \mathop {X^0 }\limits^ + A_X I/(1.2m)\ln (1 + 1.2I^{0.5} ) + 2 RT m(\beta ^{(0)X} + \beta ^{(1)X} g(y) + m C^X )$$ where I is the ionic strength, m is the molality of seasalt, A X is the Debye—Hückelslope for the volume (X = V) or compressibility(X = κ) and g(y) = (2/y 2)[1 − (1 + y)exp(x)] where y = 2I 0.5. The Pitzer parameters β(0)X,β(1)X, and C Xare fitted to functions of temperature and pressure in the form $$Y^{\text{x}} = \Sigma _{\text{i}} \Sigma _{\text{j}} a_{{\text{ij}}} (T - T_{\text{R}} )^{\text{i}} P^{\text{j}} $$ where a ij are adjustable parameters, Y X is the Pitzer parameter, T is the temperaturein K, T R = 298.15 K, and P is the applied pressure in bars (P = 0 at 1 atm or1.013 bar). The standard deviations of the seawater fits are 8.3×10−6 cm3-g−1for the specific volumes, 0.0007×10−6 bar−1 for the compressibilities, and0.63×10−6 K−1 for the thermal expansibilities. At 25°C, the measured densitiesof seawater are compared to the calculated values using Pitzer coefficients forthe major sea salts. The results agree with the measured values to within 45×10−6g-cm−3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005164911283
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    Paper (German National Licenses)
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