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Digitale Medien

Cadmium Malonate Complexation in Aqueous Sodium Trifluoromethanesulfonate Media to 75°C; Including Dissociation Quotients of Malonic Acid (1998)

Ridley, Moira K. ; Palmer, Donald A. ; Wesolowski, David J. ; [weitere]

Springer

Journal of solution chemistry 27 (1998), S. 195-216

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ISSN: 1572-8927

Schlagwort(e): Malonic acid ; propanedioic acid ; dissociation constants ; cadmium ; complexation constants ; sodium trifluoromethanesulfonate ; potentiometry

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie

Notizen: Abstract The molal formation quotients for cadmium–malonate complexes were measured potentiometrically from 5 to 75°C, at ionic strengths of 0.1, 0.3, 0.6 and 1.0 molal in aqueous sodium trifluoromethanesulfonate (NaTr) media. In addition, the stepwise dissociation quotients for malonic acid were measured in the same medium from 5 to 100°C, at ionic strengths of 0.1, 0.3, 0.6, and 1.0 molal by the same method. The dissociation quotients for malonic acid were modeled as a function of temperature and ionic strength with empirical equations formulated such that the equilibrium constants at infinite dilution were consistent, within the error estimates, with the malonic acid dissociation constants obtained in NaCl media. The equilibrium constants calculated for the dissociation of malonic acid at 25°C and infinite dilution are log K 1a=-2.86 ± 0.01 and log K 2a=-5.71 ± 0.01. A single Cd–malonate species, CdCH2C2O4, was identified from the complexation study and the formation quotients for this species were also modeled as a function of temperature and ionic strength. Thermodynamic parameters obtained by differentiating the equation with respect to temperature for the formation of CdCH2C2O4 at 25°C and infinite dilution are: K = 3.45 ± 0.09, ΔS° = 7 ± 6 kJ-mol-1, ΔS° = 91 ± 22 J-K--mol-1, and ΔC p o =400±300 JK-1mol-1.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1022638817245

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Digitale Medien

Dissociation quotients of oxalic acid in aqueous sodium chloride media to 175°C (1991)

Kettler, Richard M. ; Palmer, Donald A. ; Wesolowski, David J.

Springer

Journal of solution chemistry 20 (1991), S. 905-927

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ISSN: 1572-8927

Schlagwort(e): Oxalic acid ; ethanedioic acid ; dissociation constants ; thermodynamics ; potentiometry ; ionic strength

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie

Notizen: Abstract The first and second molal dissociation quotients of oxalic acid were measured potentiometrically in a concentration cell fitted with hydrogen electrodes. The emf of oxalic acid-bioxalate solutions was measured relative to an HCl standard solution from 25 to 125°C over 25o intervals at nine ionic strengths ranging from 0.1 to 5.0 molal (NaCl). The molal dissociation quotients and available literature data were treated in the all anionic form by a five-term equation that yielded the following thermodynamic quantities at infinite dilution and 25°C: logK1a=−1.277±0.010, ΔH 1a o =−4.1±1.1 kJ-mol−1, ΔS 1a o =38±4 J-K−1-mol−1, and ΔC p,1a o =−168±41 J-K−1-mol−1. Similar measurements of the bioxalate-oxalate system were made at 25o intervals from 0 to 175°C at seven ionic strengths from 0.1 to 5.0m. A similar regression of the experimentally-derived and published equilibrium quotients using a seven-term equation yielded the following values at infinite dilution and 25°C: logK2a=−4.275±0.006, ΔH 2a o =−6.8±0.5 kJ-mol−1, ΔS 2a o =−105±2 J-K−1-mol−1, and ΔC p,2a o =−261±12 J-K−1-mol−1.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01074952

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Digitale Medien

Dissociation quotient of benzoic acid in aqueous sodium chloride media to 250°C (1995)

Kettler, Richard M. ; Wesolowski, David J. ; Palmer, Donald A.

Springer

Journal of solution chemistry 24 (1995), S. 385-407

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ISSN: 1572-8927

Schlagwort(e): Benzoic acid ; dissociation constant ; ionization constant ; potentiometry ; ionic strength ; temperature and pressure dependence ; thermodynamics

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie

Notizen: Abstract The dissociation quotient of benzoic acid was determined potentiometrically in a concentration cell fitted with hydrogen electrodes. The hydrogen ion molality of benzoic acid/benzoate solutions was measured relative to a standard aqueous HCl solution at seven temperatures from 5 to 250°C and at seven ionic strengths ranging from 0.1 to 5.0 molal (NaCl). The molal dissociation quotients and selected literature data were fitted in the isocoulombic (all anionic) form by a six-term equation. This treatment yielded the following thermodynamic quantities for the acid dissociation equilibrium at 25°C and 1 bar: logKa=−4.206±0.006, ΔH a o =0.3±0.3 kJ-mol−1, ΔS a o =−79.6±1.0 J-mol−1-K−1, and ΔC p;a o =−207±5 J-mol−1-K−1. A five-term equation derived to describe the dependence of the dissociation constant on solvent density is accurate to 250°C and 200 MPa.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01150876

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Digitale Medien

Dissociation quotients of malonic acid in aqueous sodium chloride media to 100°C (1992)

Kettler, Richard M. ; Wesolowski, David J. ; Palmer, Donald A.

Springer

Journal of solution chemistry 21 (1992), S. 883-900

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ISSN: 1572-8927

Schlagwort(e): Malonic acid ; propanedioic acid ; dissociation constants ; thermodynamics ; potentiometry ; ionic strength

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie

Notizen: Abstract The first and second molal dissociation quotients of malonic acid were measured potentiometrically in a concentration cell fitted with hydrogen electrodes. The hydrogen ion molality of malonic acid/bimalonate solutions was measured relative to a standard aqueous HCl solution from 0 to 100°C over 25° intervals at five ionic strengths ranging from 0.1 to 5.0 molal (NaCl). The molal dissociation quotients and available literature data were treated in the all anionic form by a seven-term equation. This treatment yielded the following thermodynamic quantities for the first acid dissociation equilibrium at 25°C: logK 1a =-2.852±0.003, ΔH 1a /o =0.1±0.3 kJ-mol−1, ΔS 1a o =−54.4±1.0 J-mol−1-K−1, and ΔC p,1a o =−185±20 J-mol−1-K−1. Measurements of the bimalonate/malonate system were made over the same intervals of temperature and ionic strength. A similar regression of the present and previously published equilibrium quotients using a seven-term equation yielded the following values for the second acid dissociation equilibrium at 25°C: logK2a=−5.697±0.001, ΔH 2a o =−5.13±0.11 kJ-mol−1, ΔS 2a o =−126.3±0.4 J-mol−1-K−1, and ΔC p,2a o =−250+10 J-mol−1-K−1.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00651513

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Dissociation quotients of succinic acid in aqueous sodium chloride media to 225°C (1995)

Kettler, Richard M. ; Palmer, Donald A. ; Wesolowski, David J.

Springer

Journal of solution chemistry 24 (1995), S. 65-87

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ISSN: 1572-8927

Schlagwort(e): Succinic acid ; butanedioic acid ; dissociation constants ; thermodynamics ; potentiometry ; ionic strength

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie

Notizen: Abstract The first and second molal dissociation quotients of succinic acid were measured potentiometrically with a hydrogen-electrode, concentration cell. These measurements were carried out from 0 to 225°C over 25° intervals at five ionic strengths ranging from 0.1 to 5.0 molal (NaCl). The dissociation quotients from this and two other studies were combined and treated with empirical equations to yield the following thermodynamic quantities for the first acid dissociation equilibrium at 25°C: log K1a=−4.210±0.003; ΔH 1a 0 =2.9±0.2 kJ-mol−1; ΔS 1a 0 =−71±1 J-mol−1-K−1; and ΔC p1a 0 =−98±3 J-mol−1-K−1; and for the second acid dissociation equilibrium at 25°C: log K2a=−5.638±0.001; ΔH 2a 0 = −0.5±0.1 kJ-mol−1; ΔS 2a 0 =−109.7±0.4 J-mol−1-K−1; and ΔC p2a 0 = −215±8 J-mol−1-K−1.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00973050

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