Journal of the Chemical Society A: Inorganic, Physical, Theoretical
Journal of the Chemical Society A: Inorganic, Physical, Theoretical was published from 1966 - 1971.
Journals archive purchasers
Non-journals archive purchasers
- Purchase article PDF [£27 + taxes]
- Purchase article PDF member offer [£5 + taxes]
Free access
Paper
J. Chem. Soc. A, 1971, 33 - 38, DOI: 10.1039/J19710000033
Orthophosphates. Part II. The transformations brushite
fluoroapatite and monetite fluoroapatite in aqueous potassium fluoride solutionEdward J. Duff
The transformations brushite
fluoroapatite and monetite fluoroapatite have been investigated at 25 °C in aqueous acidic KF solutions, ca. 10–1M in F–. The transformations involve a first-order uptake of F– by the secondary orthophosphates, followed by a solid-state rearrangement to fluoroapatite with the second-order release of H2PO4–. The 
Gf° for fluoroapatite has been calculated from the brushite apatite transformation as –1524·1 kcal mol–1, and confirmed by calculation of the Gf° value for monetite as –401·1 kcal mol–1. From these results, the Gf° values of hydroxyapatite, Ca5OH(PO4)2, Ca3(PO4)2, and Ca(H2PO4)2, and Ca(H2PO4)2,H2O were calculated as –1494·2, –925·1, –677·8, and –729·5 kcal mol–1. The possibility of K substitution for Ca in fluoroapatite is discussed.
