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  • Acidic dissociation  (2)
  • dissociation constant  (2)
  • electrolytes  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Dissociation constant of acetic acid in N-methylpropionamide from 5 to 55°C and related thermodynamic quantities (1972)
    Springer
    Journal of solution chemistry 1 (1972), S. 507-516 
    Details
    ISSN: 1572-8927
    Keywords: Acetic acid ; dissociation constant ; N methylpropionamide ; nonaqueous solvents ; solute-solvent interactions ; weak acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The dissociation constant of acetic acid in N-methylpropionamide (NMP) has been determined at 11 temperatures from 5 to 55°C by measurement of the electromotive force of cells without liquid junction containing hydrogen gas electrodes and silver-silver chloride electrodes. The pK at 25°C was found to be 7.995 (molal scale) as compared with 4.756 in water; thus, acetic acid is much weaker in NMP than in water despite the higher dielectric constant of the nonaqueous solvent (176 as compared with 78.3 at 25°C). The standard changes of enthalpy and entropy for the dissociation of acetic acid were calculated from the temperature coefficient of pK, and thermodynamic functions for the transfer dissociation process were obtained. The weakness of acetic acid in NMP is discussed in terms of electrostatic effects and solute-solvent interactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00651727
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Dissociation constant of protonated tris(hydroxymethyl)aminomethane in N-methylpropionamide and related thermodynamic quantities from 10 to 55°C (1973)
    Springer
    Journal of solution chemistry 2 (1973), S. 405-415 
    Details
    ISSN: 1572-8927
    Keywords: Acidic dissociation ; dissociation constant ; emf measurements ; ionization processes ; N-methylpropionamide ; solvation ; tris-(hydroxymethyl)aminomethane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The dissociation constant of protonated tris(hydroxymethyl)aminomethane (tris·H+) in the solvent N-methylpropionamide (NMP) has been determined at intervals of 5°C from 10 to 55°C by measurement of the emf of cells without liquid junction using hydrogen and silver-silver chloride electrodes. At 25°C, pK a was found to be 8.831, as compared with 8.075 in water. The standard changes in Gibbs energy, enthalpy, and entropy for the dissociation process have been evaluated from the dissociation constant and its change with temperature. By comparison with similar data for the dissociation of tris·H+ in water, thermodynamic functions for the transfer from water to NMP have been derived. The dissociation process is isoelectric, and the solvent dielectric constant is high (ε=176 at 25°C). Consequently, electrostatic charging effects are expected to be minimal, and the change in dissociation constant depends primarily on solute-solvent interactions. The results, combined with transfer energies for HCl, tris, and tris·HCl from emf and solubility measurements, demonstrate that the decreased acidic strength of tri·H+ in NMP is attributable in large part to the fact that NMP is less effective than water in stabilizing tris and its salts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00713253
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Activity coefficient of hydrochloric acid in aqueous solutions of sodium chloride (1977)
    Springer
    Journal of solution chemistry 6 (1977), S. 385-392 
    Details
    ISSN: 1572-8927
    Keywords: Activity coefficient ; electrolytes ; mixed ; Harned coefficients ; hydrochloric acid ; mixed electrolyte solutions ; sodium chloride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Electromotive-force measurements of the cell $$Pt;H_2 \left( {g,1{\text{ }}atm} \right)|HCl\left( {{\text{m}}_A } \right),NaCl\left( {{\text{m}}_B } \right)|AgCl;Ag$$ have been made at temperatures between 5 and 45°C at values ofm A+m B of 0.1, 0.3809, 0.6729, and 0.8720 mole-kg−1. The activity coefficients of HCl in HCl/NaCl mixtures and the Harned coefficients α12 have been obtained. The change of α12 with total molality is consistent with the existence of binary interactions between H+ and Na+ ions. The linear variation of the relative partial molal heat content with the fraction of NaCl in the mixture suggests that an analog of the Harned rule exists for this thermodynamic quantity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00645511
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  • 4
    Electronic Resource
    Electronic Resource
    The temperature variation of the Harned coefficient in the system HCl−NaCl (1980)
    Springer
    Journal of solution chemistry 9 (1980), S. 449-454 
    Details
    ISSN: 1572-8927
    Keywords: Activity coefficient ; electrolytes ; mixed ; Harned coefficient ; hydrochloric acid ; mixed electrolyte solutions ; sodium chloride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The Harned coefficient measures the effect of an added electrolyte on the activity coefficient of another electrolyte. It is composite, depending partly on properties of solutions containing only one electrolyte and partly on the magnitude of a coefficient characteristic of interaction between two like charged ions in the mixed electrolyte solution. From the meager data available, the latter coefficient depends little upon temperature. The consequences of assuming temperature independence are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00647734
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  • 5
    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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    Paper (German National Licenses)
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