| Abstract: | One hundred and fifty new measurements of the solubility of witherite were used to evaluate the equilibrium constant of the reaction BaCO3(cr) = Ba2+(aq) + CO32-(aq) between 0 and 90??C and 1 atm total pressure. The temperature dependence of the equilibrium constant is given by log K = 607.642 + 0.121098T - 20011.25/T - 236.4948 log T where T is in degrees Kelvin. The log K of BaCO3(cr), the Gibbs energy, the enthalpy and entropy of the reaction at 298.15 K are -8.562, 48.87 kJ ?? mol-1, 2.94 kJ ?? mol-1 and -154.0 J ?? mol-1 ?? K-1, respectively. The equilibrium constants are consistent with an aqueous model that includes the ion pairs BaHCO3+(aq) and BaCO30(aq) Three different methods were used to evaluate the association constant of BaHCO3+(aq), and all yielded similar results. The temperature dependence of the association constant for the reaction Ba2+(aq) + HCO3-(aq) = BaHCO3+(aq) is given by log KBaHCO3+ = -3.0938 + 0.013669T. The log of the association constant, the Gibbs energy, the enthalpy and entropy of the reaction at 298.15??K are 0.982, -5.606 kJ ?? mol-1, 23.26 kJ ?? mol-1 and 96.8 J ?? mol-1 ?? K-1, respectively. The temperature dependence of the equilibrium constant for the reaction Ba2+(aq) + CO2-3(aq) = BaCO03(aq) is given by log KBaCO30 = 0.113 + 0.008721T. The log of the association constant, the Gibbs energy, the enthalpy and entropy of the reaction at 298.15?? K are 2.71, -15.49 kJ ?? mol-1, 14.84 kJ ?? mol-1 and 101.7 J?? mol-1 ?? K-1. The above model leads to reliable calculations of the aqueous speciation and solubility of witherite in the system BaCO3-CO2-H2O from 0 to more than 90??C. Literature data on witherite solubility were re-evaluated and compared with the results of this study. Problems in the thennodynamic selections of Ba compounds are considered. Newer data require the revision of ??fH?? and ??fG?? of Ba2+(aq) to -532.5 and -555.36 kJ ?? mol-1, respectively, for agreement with solubility data. ?? 1986. |
| Genre: | Article |
| ProdID: | 70015035 |
| Citation Author: | Busenberg, E.; Plummer, L. N. |
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| Citation End Page: | 2233 |
| Citation Issue: | 10 |
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| Citation Language: | English |
| Citation Larger Work Title: | Geochimica et Cosmochimica Acta |
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| Citation Number Of Pages: | 9 |
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| Citation Search Results Text: | The solubility of BaCO3(cr) (witherite) in CO2-H2O solutions between 0 and 90??C, evaluation of the association constants of BaHCO3+(aq) and BaCO30(aq) between 5 and 80??C, and a preliminary evaluation of the thermodynamic properties of Ba2+(aq); 1986; Article; Journal; Geochimica et Cosmochimica Acta; Busenberg, E.; Plummer, L. N. |
| Citation Start Page: | 2225 |
| Citation Volume: | 50 |
| Citation Year: | 1986 |
| Type: | citation/reference |
| Text: | The solubility of BaCO3(cr) (witherite) in CO2-H2O solutions between 0 and 90??C, evaluation of the association constants of BaHCO3+(aq) and BaCO30(aq) between 5 and 80??C, and a preliminary evaluation of the thermodynamic properties of Ba2+(aq); 1986; Article; Journal; Geochimica et Cosmochimica Acta; Busenberg, E.; Plummer, L. N. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Wed, 1 Jan 1986 00:00 -0600 |
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