thumbnail

The solubility of strontianite (SrCO3) in CO2-H2O solutions between 2 and 91??C, the association constants of SrHCO+3(aq) and SrCO03(aq) between 5 and 80??C, and an evaluation of the thermodynamic properties of Sr2+(aq) and SrCO3(cr) at 25??C and 1 atm total pressure

Geochimica et Cosmochimica Acta

By:
, ,

Links

  • The Publications Warehouse does not have links to digital versions of this publication at this time

Abstract

Seventy new measurements (SrT-Pco2 of the solubility of strontianite were used to evaluate the equilibrium constant for the reaction SrCO3(cr) = Sr2+(aq) + CO2-3(aq) between 2 and 91 ??C. The temperature dependence of the equilibrium constant is given by the expression Log K = 155.0305 - 7239.594/T - 56.58638 log T where T is in degrees Kelvin. The log K of strontianite, the Gibbs energy, enthalpy and entropy of the reaction at 25??C are -9.271 ?? 0.020, 52.919 ?? 0.08 kJ ?? mol-1, -1.67 ?? 1.30 kJ ?? mol-1, and -183.1 ?? 4.0 J ?? mol-1 ?? K-1, respectively. The equilibrium constants are consistent with an aqueous model that includes the ion pairs SrHCO+3(aq) and SrCO03(aq) which were evaluated by potentiometric methods between 5 and 80??C. The equilibrium constant for the association reaction Sr2+(aq) + HCO-3(aq) = SrHCO+3aq) is given by the expression Log KSrHCO+3 = -3.248 + 0.014867T. The log of the association constant, the Gibbs energy, enthalpy and entropy of the reaction at 25??C are 1.18, -6.76 kJ ?? mol-1, 25.30 kJ ?? mol-1, and 107.5 J ?? mol-1 ?? K-1, respectively. The equilibrium constant for the association reaction Sr2+(aq) + CO2-3(aq) = SrCO03aq) is given by the expression Log KSrCO03 = -1.019 + 0.012826T. The log of the association constant, the Gibbs energy, enthalpy, and entropy of the reaction at 25??C are 2.81, -16.01 kJ ?? mol-1,21.83 kJ ?? mol-1, and 126.9 J ?? mol-1 ?? K-1, respectively. These results lead to reliable calculation of the aqueous speciation and solubility of strontianite in the system SrCO3-CO2-H2O from 0 to more than 90??C. Literature data on the solubility of strontianite have been evaluated and compared with these results. Our new data for strontianite have been used in an evaluation of the thermodynamic properties of Sr2+(aq), SrCO3(cr) and related compounds. The following values are recommended for the standard enthalpy (kJ ?? mol-1), Gibbs energy (kJ ?? mol-1), and entropy (J ?? mol-1 ?? K-1), respectively, of Sr2+aq): -550.90 ?? 0.50, -563.83 ?? 0.8 and -31.50 ?? 2.0, and for SrCO3(cr): -1225.77 ?? 1.1, -1144.73 ?? 1.0 and 97.2. ?? 1984.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
The solubility of strontianite (SrCO3) in CO2-H2O solutions between 2 and 91??C, the association constants of SrHCO+3(aq) and SrCO03(aq) between 5 and 80??C, and an evaluation of the thermodynamic properties of Sr2+(aq) and SrCO3(cr) at 25??C and 1 atm total pressure
Series title:
Geochimica et Cosmochimica Acta
Volume
48
Issue:
10
Year Published:
1984
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
2021
Last page:
2035
Number of Pages:
15