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  • Activity coefficient  (4)
  • dissociation constants  (3)
  • Harned's equations  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Thermodynamics of the dissociations of glycine in 50 mass % aqueous monoglyme from 5 to 55°C (1977)
    Springer
    Journal of solution chemistry 6 (1977), S. 475-485 
    Details
    ISSN: 1572-8927
    Keywords: Zwitterions ; ampholyte ; dissociation constants ; glycine ; solute-solvent interactions ; ionization ; activity coefficient ; monoglyme-water ; aqueous mixtures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Electromotive-force measurements on cells without liquid junction have been used to determine the pK 1 and pK 2 values of glycine in 50 mass % aqueous monoglyme at 11 temperatures from 5 to 55°C. The change in the first dissociation constant is given as a function of the thermodynamic temperatureT by the equation pK 1=−2058.6/T+15.421−0.019169T, whereas that for the second dissociation constant is given by the equation pK 2=1200.5/T+6.7211−0.0042897T. At 25°C, the pK 1 is 2.806 in the mixed solvent, as compared with 2.350 in water; hence, protonated glycine becomes a weaker acid in the mixed solvent. The pK 2 is 9.453 in the mixed solvent, whereas that in water is 9.780, suggesting that the second dissociation process becomes stronger in terms of acidity. The thermodynamic quantities ΔG o, ΔH o, ΔS o, and ΔC p o have been calculated, and the results have been discussed with respect to preferential solvation and also compared with similar data for the same two processes in 50 mass % methanol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00645841
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  • 2
    Electronic Resource
    Electronic Resource
    The system HCl+InCl3+H2O from 5 to 55°C: Application of Harned's rule (1996)
    Springer
    Journal of solution chemistry 25 (1996), S. 1241-1259 
    Details
    ISSN: 1572-8927
    Keywords: Activity coefficient ; emf ; Harned's equations ; hydrochloric acid ; indium chloride ; mixtures of electrolytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Electromotive-force measurements of cells containing hydrochloric acid and indium chloride have been made to determine the variation of the log of the activity coefficient of hydrochloric acid with change in the amount of indium chloride in the solution. The simpler Harned equations have been used to fit the data. The quadratic terms in the Harned equations for the activity coefficients of HCl in the salt mixtures are required for a good fit of the 968 experimental emf data points at all the experimental ionic strengths and temperatures. The more convenient Pitzer ion-interaction treatment of the data will be reported in a separate publication which will include the values of the Pitzer parameters for pure InCl3(aq), and mixing parameters for H+−In+3 and H+−In+3−Cl−. A comprehensive investigation on the mixed electrolyte solutions at 11 different constant total ionic strengths ranging from 0.05 to 3.5 mol-kg−1 was made at 11 temperatures from 5 to 55°C using the cell without liquid junction of the type: Pt,H2(g, 1 atm)|HCl(m A)+InCl3(m B)+H2O|AgCl,AG (A).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00972649
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  • 3
    Electronic Resource
    Electronic Resource
    Second Dissociation Constant of Two Substituted Aminomethanesulfonic Acids in Water from 5 to 55°C (1997)
    Springer
    Journal of solution chemistry 26 (1997), S. 1209-1216 
    Details
    ISSN: 1572-8927
    Keywords: MES ; TES ; emf ; standard potential ; zwitterion ; buffer solution ; activity coefficients ; dissociation constants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The equilibrium constants for the dissociation steps of (4-morpholineethanesulfonic acid) (MES) and (2-{[tris(hydroxymethyl)methyl]-1-ethanesulfonic acid (TES) have been determined at 12 and 7 different temperatures, respectively, from 5 to 55°C. The emf measurements were carried out by using a cell without liquid junction of the type: Pt; H2 (g, 1 atm) | buffer(m1), Na salt of buffer(m2), NaCl(m3) | AgCl, Ag. The pK 2 values of MES and TES at 25°C are 6.269 and 7.550. The thermodynamic quantities for the dissociation process have been calculated. These zwitterionic compounds are useful for pH control as standard buffers in the physiological region of pH 5.50 to 6.50 for MES, 6.5 to 7.5 for TES, respectively. Reliable measurements of the pH at isotonic saline solution (I = 0.16m) such as blood and plasma are important for clinical diagnosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022937324983
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  • 4
    Electronic Resource
    Electronic Resource
    Activity Coefficients for the System HCl +GaCl3 + H2O from 5 to 55°C (1999)
    Springer
    Journal of solution chemistry 28 (1999), S. 933-947 
    Details
    ISSN: 1572-8927
    Keywords: Activity coefficient ; emf ; Harned's equations ; hydrochloric acid ; gallium chloride ; electrolyte mixtures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Activity coefficients for HCl in HCl + GaCl3 + H2O at eleven different temperatures from 5 to 55°C have been determined at total experimental ionic strengths from 0.01 to 3.0 mol-kg−1 using a cell of the type: Pt; H2(g, 1 atm)|HCl (mA) + GaCl3(mB)|AgCl, Ag(A) The results for the 770 experimental emf data points have been used to determine the variation of the activity coefficients of HCl with the change in molality of GaCl3 in the solution. It is found that the linear form of Harned's rule is not obeyed for this system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021740416488
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  • 5
    Electronic Resource
    Electronic Resource
    Thermodynamics of the GaCl3-HCl-H2O System at 25°C (2000)
    Springer
    Journal of solution chemistry 29 (2000), S. 289-297 
    Details
    ISSN: 1572-8927
    Keywords: Activity coefficient ; emf ; hydrochloric acid ; gallium chloride ; Pitzer equations ; hydrolysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A comprehensive equation for the thermodynamic properties of the systemGaCl3-HCl-H2O at 25°C in the ion-interaction (Pitzer) equation form has been generatedon the basis of a recent and comprehensive array of electrochemical cellmeasurements of the HCl activity at total stoichiometric ionic strengths from 0.01 to 3.0mol-kg−1. Alternate equations with and without explicit consideration of thehydrolyzed product GaOH2+ as a separate species have been tested. Excellentagreement is obtained between the calculated and measured cell potentials forthe formulation, which includes GaOH2+ as an additional species. The effect offurther hydrolysis as well as that of complex formation has been found to benegligible. While a satisfactory set of Pitzer parameters has been found, it wasnot possible to obtain a unique thermodynamic representation for this systembecause of large uncertainties in the first hydrolysis constant of Ga(III) and becauseof redundancies and intrinsic correlations between some of the Pitzer parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005154501655
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  • 6
    Electronic Resource
    Electronic Resource
    The system H2O−HCl−NH4Cl at 25°C: A study of Harned's rule (1974)
    Springer
    Journal of solution chemistry 3 (1974), S. 837-845 
    Details
    ISSN: 1572-8927
    Keywords: Activity coefficient ; ammonium chloride ; Harned's rule ; hydrochloric acid ; mixtures of electrolytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Electromotive-force measurements of cells containing hydrochloric acid and ammonium chloride at constant total molality have been used to determine the variation of the logarithm of the activity coefficient of hydrochloric acid with change in the amount of ammonium chloride in the solution. The results are interpreted in the light of the recent work of Pitzer, and it is found that Harned's rule holds for both electrolytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00645689
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  • 7
    Electronic Resource
    Electronic Resource
    Solute-solvent effects in the acidic dissociation of the ampholyte N-tris(hydroxymethyl)methylglycine (“tricine”) in 50 mass % methanol-water solvent (1974)
    Springer
    Journal of solution chemistry 3 (1974), S. 905-916 
    Details
    ISSN: 1572-8927
    Keywords: Acidic dissociation ; ampholyte dissociation ; dissociation constants ; ionization ; methanol-water solvents ; solute-solvent effects ; N-Tris(hydroxymethyl)methylglycine (“tricine”) ; zwitterions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pK values for the two acidic dissociation steps of the ampholyte N-tris-(hydroxymethyl)methylglycine (“tricine”) in 50 mass % methanol-water solvent have been determined by emf measurements of cells of the type Pt|H2(g, 1 atm), tricine buffer, Br−, AgBr|Ag over the range 5 to 50°C (pK 1)and 5 to 60°C (pK 2).The standard thermodynamic quantities ΔHo, ΔSo, and ΔC p o for the two dissociation processes have been derived and are compared with the corresponding values for tricine and the parent glycine in water and with those for other acids in 50 mass % methanol-water solvent. Both tricine and protonated tricine become weaker acids when methanol is added to the aqueous solvent. It appears that a strong stabilization of the zwitterion in water is responsible for this behavior. This conclusion is supported by comparing the changes in entropy and heat capacity for the dissociation of tricine with the values of these quantities for the dissociation of “model” acids of simple structure, such as ammonium ion and acetic acid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00647944
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