Solubility Pattern of CaSO4·2H2O in the System NaCl + CaCl2 + H2O and Solution Densities at 35 
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- 作者：Arvind Kumar ; Rahul Sanghavi ; V. P. Mohandas
- 刊名：Journal of Chemical & Engineering Data
- 出版年：2007
- 出版时间：May 2007
- 年：2007
- 卷：52
- 期：3
- 页码：902 - 905
- 全文大小：75K
- 年卷期：v.52,no.3(May 2007)
- ISSN：1520-5134
文摘
The solubility of CaSO4·2H2O was determined in aqueous NaCl solutions up to very high salinities and constantCaCl2 concentrations at 35 
C. Addition of CaCl2 into the aqueous NaCl system reduces the solubility of CaSO4·2H2O quite dramatically while maintaining the basic pattern of the solubility curve. Mean ionic activity coefficients
± of CaSO4·2H2O derived using the extended Debye-Hückel law with quadratic terms decrease with an increasein ionic strength. A comparison of the value of the thermodynamic solubility product constant, Ksp(th) of CaSO4·2H2O to the solubility product Ksp obtained from the observed solubility data indicate sizable differences. Thishas been explained through a combination of the extended Debye-Hückel law and ion association theory. Wealso measured accurate densities for the quaternary system CaSO4·2H2O + NaCl + CaCl2 + H2O at 35 C. Thedensity of the solution increases linearly with an increase in concentration. Solutions containing higher amountsof CaCl2 were found to be less dense when compared at the same ionic strengths. Solubility and density data asa function of concentration have been correlated using polynomial and linear fits by the method of least squares.These studies are of relevance in the production of salt with low impurities of Ca2+ and SO42- ions.
C. Addition of CaCl2 into the aqueous NaCl system reduces the solubility of CaSO4·2H2O quite dramatically while maintaining the basic pattern of the solubility curve. Mean ionic activity coefficients± of CaSO4·2H2O derived using the extended Debye-Hückel law with quadratic terms decrease with an increasein ionic strength. A comparison of the value of the thermodynamic solubility product constant, Ksp(th) of CaSO4·2H2O to the solubility product Ksp obtained from the observed solubility data indicate sizable differences. Thishas been explained through a combination of the extended Debye-Hückel law and ion association theory. Wealso measured accurate densities for the quaternary system CaSO4·2H2O + NaCl + CaCl2 + H2O at 35 C. Thedensity of the solution increases linearly with an increase in concentration. Solutions containing higher amountsof CaCl2 were found to be less dense when compared at the same ionic strengths. Solubility and density data asa function of concentration have been correlated using polynomial and linear fits by the method of least squares.These studies are of relevance in the production of salt with low impurities of Ca2+ and SO42- ions.