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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.
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. This acid can be degraded to release HF thermally and by hydrolysis: H 2 SiF ...
It is normally accomplished by adding one of three compounds to the water: sodium fluoride, fluorosilicic acid, or sodium fluorosilicate. Sodium fluoride (NaF) was the first compound used and is the reference standard. [39] It is a white, odorless powder or crystal; the crystalline form is preferred if manual handling is used, as it minimizes ...
Hydrofluoric acid and its anhydrous form, hydrogen fluoride, ... Originally, sodium fluoride was used to fluoridate water; hexafluorosilicic acid (H 2 SiF 6) ...
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).
Unlike other hydrohalic acids, such as hydrochloric acid, hydrogen fluoride is only a weak acid in water solution, with acid dissociation constant (pK a) equal to 3.19. [36] HF's weakness as an aqueous acid is paradoxical considering how polar the HF bond is, much more so than the bond in HCl, HBr, or HI. The explanation for the behavior is ...
In water, ammonium bifluoride exists in chemical equilibrium with hydrofluoric acid and heating releases hydrogen fluoride gas. [9] Consequently, there is an equivalent toxicological risk as is present with hydrofluoric acid, and the same safety precautions apply. [10] [9] Ammonium bifluoride is used in some automotive wheel cleaning products.
This substance is commonly called "commercial ammonium fluoride". The word "neutral" is sometimes added to "ammonium fluoride" to represent the neutral salt [NH 4]F as opposed to the "acid salt" (NH 4 HF 2). The acid salt is usually used in preference to the neutral salt in the etching of glass and related silicates. This property is shared ...