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Abstract
The solubility, at 25°C, of calcium citrate, Ca3(C6H5O7)2. 4H2O, in NaClO4 solutions in the molality (m) range 0–3.5, has been determined by potentiometric titration with EDTA, using the Hg2+/Hg half-cell. The increase of solubility with m has been explained with the specific interaction theory by assuming, for Ca3(C6 H5 O7)2.4 H2 O(s) ⇄3Ca2+ + 26H55O7 3−, log Ks0= −17.81 ± 0.03 and the interaction coefficient between Na+ and C6H5O7 3− ions equal to 0.08 ± 0.03 −(0.06 ± 0.01)m. This coefficient allows the extrapolation to the infinite dilution reference state of stability constants determined in concentrated ionic media. Results of calculations compare well with those of the literature.
ACKNOWLEDGMENT
The work has been financially supported by MURST, Rome.