Experimental study of fluorite solubility in acidic solutions as a method for boron fluoride complexes studying


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Abstract

Fluorite solubility in HCl and HF solutions with varied concentrations of boric acid was studied at 81, 155, and 208°C and saturated vapor pressure. Our experimental results demonstrate that fluorite solubility increases with increasing B(OH)3 concentration, and this was interpreted as the formation of the BF3OH–complex (Ryss, 1956). The experimental data were used to determine, using the OptimA software, the free energies of formation of HF°(aq) and, which were then used to calculate the constants of the reactions HF = H+ + F (1) and B(OH)3(aq) + 2H+ + 3 F (2). The pK1 values are 3.71 ± 0.013, 4.28 ± 0.015, and 4.89 ± 0.017 and pK2 13.60 ± 0.02, 13.99 ± 0.02, and 14.95 ± 0.03 at saturated vapor pressure and 81, 155, and 208°C, respectively.

About the authors

M. E. Tarnopolskaia

Geological Faculty

Author for correspondence.
Email: mashatarnopolskaya@yandex.ru
Russian Federation, Moscow, 119899

A. Yu. Bychkov

Geological Faculty; Vernadsky Institute of Geochemistry and Analytical Chemistry (GEOKhI)

Email: mashatarnopolskaya@yandex.ru
Russian Federation, Moscow, 119899; Moscow, 119991

Yu. V. Shvarov

Geological Faculty; Vernadsky Institute of Geochemistry and Analytical Chemistry (GEOKhI)

Email: mashatarnopolskaya@yandex.ru
Russian Federation, Moscow, 119899; Moscow, 119991

Yu. A. Popova

Geological Faculty

Email: mashatarnopolskaya@yandex.ru
Russian Federation, Moscow, 119899

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