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  • 1
    Electronic Resource
    Electronic Resource
    Dissociation quotients of succinic acid in aqueous sodium chloride media to 225°C (1995)
    Springer
    Journal of solution chemistry 24 (1995), S. 65-87 
    Details
    ISSN: 1572-8927
    Keywords: Succinic acid ; butanedioic acid ; dissociation constants ; thermodynamics ; potentiometry ; ionic strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00973050
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  • 2
    Electronic Resource
    Electronic Resource
    Dissociation quotients of malonic acid in aqueous sodium chloride media to 100°C (1992)
    Springer
    Journal of solution chemistry 21 (1992), S. 883-900 
    Details
    ISSN: 1572-8927
    Keywords: Malonic acid ; propanedioic acid ; dissociation constants ; thermodynamics ; potentiometry ; ionic strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00651513
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  • 3
    Electronic Resource
    Electronic Resource
    Dissociation quotients of oxalic acid in aqueous sodium chloride media to 175°C (1991)
    Springer
    Journal of solution chemistry 20 (1991), S. 905-927 
    Details
    ISSN: 1572-8927
    Keywords: Oxalic acid ; ethanedioic acid ; dissociation constants ; thermodynamics ; potentiometry ; ionic strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01074952
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  • 4
    Electronic Resource
    Electronic Resource
    Dissociation quotient of benzoic acid in aqueous sodium chloride media to 250°C (1995)
    Springer
    Journal of solution chemistry 24 (1995), S. 385-407 
    Details
    ISSN: 1572-8927
    Keywords: Benzoic acid ; dissociation constant ; ionization constant ; potentiometry ; ionic strength ; temperature and pressure dependence ; thermodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01150876
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  • 5
    Electronic Resource
    Electronic Resource
    Cadmium Malonate Complexation in Aqueous Sodium Trifluoromethanesulfonate Media to 75°C; Including Dissociation Quotients of Malonic Acid (1998)
    Springer
    Journal of solution chemistry 27 (1998), S. 195-216 
    Details
    ISSN: 1572-8927
    Keywords: Malonic acid ; propanedioic acid ; dissociation constants ; cadmium ; complexation constants ; sodium trifluoromethanesulfonate ; potentiometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022638817245
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  • 6
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    The Geologic Context of Wonderstone: A Complex, Outcrop-Scaled Pattern of Iron-Oxide Cement (2016)
    Society for Sedimentary Geology
    Details
    Publication Date: 2016-05-01
    Description: Although siderite is a widespread early diagenetic mineral in fluvial systems, it is unstable in oxidizing environments and destroyed in permeable rocks that experience uplift and exhumation. The products of siderite oxidation, however, (mm- to cm-scale rhombs, concretions, and complex bands of iron-oxide cement) are widespread in the rock record of fluvial systems. The fluvial channels of the Shinarump Member of the Chinle Formation in southern Utah and northern Arizona, U.S.A., provide an excellent suite of examples of diagenetic features produced by Triassic and Neogene oxidation of early diagenetic siderite. These diagenetic features also provide direct evidence of the level of the water table during deposition of the Shinarump member. Large, in situ , discoidal concretions containing preserved siderite are present in Shinarump floodplain siltstones. Rip-up clasts derived from the siltstones developed iron-oxide rinds during late-stage, near-surface oxidation. These two structures show that floodplain silts contained abundant organic matter and methanic pore water. Groundwater recharging through these silts carried reducing water through underlying sand bodies and discharged into active channels. Degassing of CO2 and methanogenesis caused rhombic crystals of siderite to precipitate in channel sands during these wet intervals. Some of this siderite may have been oxidized during dry intervals when groundwater circulation reversed, but most siderite in the channel sands was preserved until the Shinarump was exhumed during the Neogene. As oxygenated near-surface water entered joints in the lithified Shinarump, colonies of iron-oxidizing microbes living in the phreatic zone occupied redox boundaries and used the rhombic crystals of siderite in the sandstone and the spherulitic siderite in transported siltstone intraclasts as their sources of energy and carbon. The ferrous iron released from dissolving siderite within the intraclasts was oxidized at the siltstone–sandstone contact, generating rinded concretions similar to those in the Cretaceous Dakota Formation. Complex banding known as wonderstone was produced in the channel sandstones from oxidation of the rhombic siderite; the pattern is a combination of Liesegang bands and microbially mediated cements. The preserved rhombs are pseudomorphs after siderite crystals that were either oxidized during Triassic dry intervals, or escaped Neogene microbial oxidation in the phreatic zone, only to be oxidized abiotically in the vadose zone. Microbes are likely oxidizing Shinarump siderite a few kilometers down dip of outcrops with exposed wonderstone. At such locations, the Shinarump is in contact with overlying water-saturated Quaternary alluvium.
    Print ISSN: 1527-1404
    Electronic ISSN: 1938-3681
    Topics: Geosciences
    Published by Society for Sedimentary Geology
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