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Diffraction Patterns and Solubility Products of Several Divalent Manganese Phosphate Compounds
Author(s) -
Boyle F. W.,
Lindsay W. L.
Publication year - 1985
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/sssaj1985.03615995004900030046x
Subject(s) - manganese , divalent , solubility , chemistry , phosphate , dissociation constant , ionic strength , solubility equilibrium , dissociation (chemistry) , inorganic chemistry , diffraction , x ray crystallography , crystallography , aqueous solution , organic chemistry , biochemistry , receptor , physics , optics
Four divalent Mn phosphate compounds were prepared and identified. The compound, Mn 3 (PO 4 ) 2 ·3H 2 O slowly transformed to Mn 5 H 2 (PO 4 ) 4 ·4H 2 O, when the solid was left in contact with the mother liquor. Dissociation constants were determined for the following reactions:log K ∘MnHPO 4 ⋅ 3 H 2 O ( c ) + H + ⇌ Mn 2 + + H 2PO 4 − − 0.24Mn 3(PO 4 ) 2 ⋅ 3 H 2 O ( c ) + 4 H + ⇌ 3 Mn 2 + + 2 H 2PO 4 − 8.40Mn 5 H 2(PO 4 ) 4 ⋅ 4 H 2 O ( c ) + 6 H + ⇌ 5 Mn 2 + + 4 H 2PO 4 − 4.76where log K · is the log of the equilibrium constant, ( K ·). The mineral Mn(H 2 PO 4 ) 2 ·2H 2 O (manganese [II] di‐[dihydrogen phosphate] dihydrate) was identified, but its solubility constant was not determined because of high ionic strength corrections. X‐ray diffraction patterns, densities, and refractive indices were determined for the four minerals.