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Although hydrofluoric acid is regarded as a weak acid, it is very corrosive, even attacking glass when hydrated. [ 20 ] Dilute solutions are weakly acidic with an acid ionization constant K a = 6.6 × 10 −4 (or p K a = 3.18 ), [ 10 ] in contrast to corresponding solutions of the other hydrogen halides, which are strong acids ( p K a < 0 ).
Aqueous solutions of HF are called hydrofluoric acid. When dilute, hydrofluoric acid behaves like a weak acid, unlike the other hydrohalic acids, due to the formation of hydrogen-bonded ion pairs [H 3 O + ·F −]. However concentrated solutions are strong acids, because bifluoride anions are predominant, instead
An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula . For example, a solution of table salt , also known as sodium chloride (NaCl), in water would be represented as Na + (aq) + Cl − (aq) .
Hydrofluoric acid is complicated because its strength depends on the concentration owing to the effects of homoconjugation. As solutions in non-aqueous solvents, such as acetonitrile , the hydrogen halides are only modestly acidic however.
Subunit of crystal structure of [H 3 O] + [BF 4] − highlighting the hydrogen bonding between the cation and the anion. Aqueous solutions of H[BF 4] are produced by dissolving boric acid in aqueous hydrofluoric acid. [8] [9] Three equivalents of HF react to give the intermediate boron trifluoride and the fourth gives fluoroboric acid:
Acid strength is the tendency of an acid, symbolised by the chemical formula, to dissociate into a proton, +, and an anion, .The dissociation or ionization of a strong acid in solution is effectively complete, except in its most concentrated solutions.
Potassium fluoroborate is obtained by treating potassium carbonate with boric acid and hydrofluoric acid. B(OH) 3 + 4 HF → HBF 4 + 3 H 2 O 2 HBF 4 + K 2 CO 3 → 2 KBF 4 + H 2 CO 3. Fluoroborates of alkali metals and ammonium ions crystallize as water-soluble hydrates with the exception of potassium, rubidium, and cesium.
The reaction of silver acetylide with a concentrated solution of silver(I) fluoride results in the formation of a chandelier-like [Ag 10] 2+ cluster with endohedral acetylenediide. [24] Tetralkylammonium fluorides can be conveniently prepared in the laboratory by the reaction of the tetralkylammonium bromide with an aqueous AgF solution. [25]: 430