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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.
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 ...
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 ...
The bifluoride ion has a linear, centrosymmetric structure (D ∞h symmetry), with an F−H bond length of 114 pm. [1] The bond strength is estimated to be greater than 155 kJ/mol. [2] In molecular orbital theory, the atoms are modeled to be held together by a 3-center 4-electron bond (symmetrical hydrogen bond), [3] in a sort of hybrid between a hydrogen bond and a covalent bond.
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.
The salt was prepared by Edmond Frémy by treating potassium carbonate or potassium hydroxide with hydrofluoric acid: 2 HF + KOH → K[HF 2] + H 2 O. With one more equivalent of HF, K[H 2 F 3] (CAS RN 12178-06-2, m.p. 71.7 °C [4]) is produced: HF + K[HF 2] → K[H 2 F 3] Thermal decomposition of K[HF 2] gives hydrogen fluoride: K[HF 2] → HF + KF
One use of conjugate acids and bases lies in buffering systems, which include a buffer solution. In a buffer, a weak acid and its conjugate base (in the form of a salt), or a weak base and its conjugate acid, are used in order to limit the pH change during a titration process. Buffers have both organic and non-organic chemical applications.
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 ...