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Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water. Solutions of HF are colorless, acidic and highly corrosive . A common concentration is 49% (48-52%) but there are also stronger solutions (e.g. 70%) and pure HF has a boiling point near room temperature.
Buffered oxide etch (BOE), also known as buffered HF or BHF, is a wet etchant used in microfabrication.It is a mixture of a buffering agent, such as ammonium fluoride NH 4 F, and hydrofluoric acid (HF).
Hydrogen fluoride is typically produced by the reaction between sulfuric acid and pure grades of the mineral fluorite: [14] CaF 2 + H 2 SO 4 → 2 HF + CaSO 4 About 20% of manufactured HF is a byproduct of fertilizer production, which generates hexafluorosilicic acid .
The Hammett acidity function (H 0) is a measure of acidity that is used for very concentrated solutions of strong acids, including superacids.It was proposed by the physical organic chemist Louis Plack Hammett [1] [2] and is the best-known acidity function used to extend the measure of Brønsted–Lowry acidity beyond the dilute aqueous solutions for which the pH scale is useful.
On the other hand, if a chemical is a weak acid its conjugate base will not necessarily be strong. Consider that ethanoate, the conjugate base of ethanoic acid, has a base splitting constant (Kb) of about 5.6 × 10 −10, making it a weak base. In order for a species to have a strong conjugate base it has to be a very weak acid, like water.
This effect arises from the stabilization of the conjugate base by its formation of a hydrogen bond to the parent acid. A well known case is hydrofluoric acid, which is a significantly stronger acid when concentrated than when dilute due to the following equilibria: 2 HF H 2 F + + F − (autoionization of HF)
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.
Sodium bifluoride reacts with water or moist skin to produce hydrofluoric acid. It also gives off hydrofluoric acid and hydrogen gas when it is heated to a gaseous state. The chemical can decompose upon contact with strong acids, strong bases, metal, water, or glass. [3] Sodium bifluoride also engages in violent reactions with chromyl chloride ...