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Solubility Criteria for the Existence of Calcium and Aluminum Phosphates in Soils
Author(s) -
Clark J. S.,
Peech Michael
Publication year - 1955
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1955.03615995001900020015x
Subject(s) - solubility , lime , chemistry , phosphate , calcium , soil water , mineralogy , aluminium , inorganic chemistry , solubility equilibrium , phase diagram , phase (matter) , geology , materials science , metallurgy , organic chemistry , soil science
The solubilities of calcium phosphates may be represented on a single solubility diagram in which functions of the chemical potentials of Ca(OH) 2 and Ca(H 2 PO 4 ) 2 are used as co‐ordinates. In the presence of solid phase CaCO 3 , the chemical potential of lime (the value of pH ‐ ½pCa) depends upon the partial pressure of CO 2 in the atmosphere. Solubility determinations showed that neither dicalcium phosphate nor hydroxyapatite was present in the soil or clay systems studied. A similar solubility diagram may be constructed for the aluminum phosphates using functions of the chemical potentials of Al(OH) 3 and Al(H 2 PO 4 ) 3 as co‐ordinates. In the absence of reliable solubility data, the existence of the aluminum phosphates in the soils studied could not be established.