Equilibrium on the hydrolysis of boron trifluoride in large amount of water

Abstract

In order to clarify the equilibrium components in the hydrolysis solution of boron trifluoride(BF₃-H₂O), the BF₃-H₂O was prepared by mixing BF₃-CH₃OH with large amount of water, in which the stoichiometric concentration of BF₃ is less than 0.1 mol/L. Two ionic equilibrium models were proposed to simulate the hydrolysis equilibrium of BF₃ and tested by special acid-base titration technique. The most accurate ion equilibrium constants were determined. The model, which was assumed to have no HF, was proved to be more representative for the real system and used to simulate the hydrolysis equilibrium of BF₃. The simulation suggested that H⁺, BF₄ ^-, BF₃OH^- and H₃BO₃ were the main species in the dilute hydrolysis solution, while BF₂(OH)₂ ^- and F^- were insignificant species whose concentrations were both in the order of 10^-4 mol/L magnitude, and BF(OH)₃ ^- could be omitted because its concentration almost equaled zero. Meanwhile, the equilibrium constant of the overall ionic reaction at 25 °C was obtained as 161.6.

Keywords

boron trifluoride / hydrolysis equilibrium / ionic equilibrium / simulation

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