Product Name: Hydrogen Fluoride

Cas: 7664-39-3

Molecular Formula: Fh

Molecular Weight: 20.01

Einecs: 231-634-8

Product Description

Hydrofluoric acid (HF for short) is an aqueous solution of hydrogen fluoride gas, also known as fluoric acid, bone acid, bone water, drilling water, rust remover, pickling. It is a colorless, transparent to light yellow fuming liquid at room temperature with a pungent odor. Its specific gravity is 0.98, slightly lighter than water, and its boiling point is 19.4℃. It is very volatile and emits white smoke when placed in the air. An aqueous solution containing less than 60% hydrogen fluoride is a colorless, clear, fuming liquid. Industrial products are usually aqueous solutions with 40-45% HF content. It has a pungent odor, reacts with sulfur trioxide or chlorosulfonic acid to produce fluorosulfonic acid, reacts with halogenated aromatic hydrocarbons, alcohols, alkenes, and hydrocarbons to produce fluorine-containing organic matter, and dissolves in water to produce highly corrosive acids, which are medium-strength acids. It has a strong odor and is extremely toxic. It is easy to cause ulcers when it touches the skin, which is more severe than any other acid. If its vapor is inhaled, it can be fatal, so strict attention must be paid when using it.

1. Hydrofluoric acid can also react with general metals, metal oxides, and hydroxides to produce various metal fluoride salts, but the reaction is not as intense as hydrochloric acid. Gold, platinum, lead, paraffin, and some plastics (polyethylene, etc.) do not react with it, so it can be used as a container.

2. It is extremely corrosive and can corrode glass and silicates to produce gaseous silicon tetrafluoride. The reaction formula is as follows: SiO2 + 4HF → H2O + SiF4↑. Glass is a silicon compound, so hydrofluoric acid cannot be placed in a glass container.

3. Hydrofluoric acid can form acid salts. Hydrofluoric acid is originally a monobasic acid, but Chemicalbook can produce a series of acid salts such as NaHF2, KHF2, NH4HF2, etc., which are the other three types of hydrohalic acids.

4. The weak acidity of hydrofluoric acid, because the ability of hydrogen atoms and fluorine atoms to combine is relatively strong, makes hydrofluoric acid unable to completely dissociate in water. Among the hydrohalic acids, only hydrofluoric acid is a weak acid (its ionization constant is 3.5x10^-4, and its apparent ionization degree is 10% when the concentration is 0.1 mol.L^-1. Therefore, HF can barely be regarded as a medium-strong acid. The degree of ionization when concentrated is greater than that when dilute, which is different from general weak electrolytes).

Hydrofluoric acid Properties

Chemical properties

Colorless fuming liquid. When dissolved in water, it releases heat violently to form hydrofluoric acid.

Uses

1. Mainly used as a raw material for fluorine-containing compounds, also used in the manufacture of aluminum fluoride and cryolite, semiconductor surface etching and as a catalyst for alkylation

2. Used as a strong acid corrosive in the electronics industry, it can be used in combination with nitric acid, acetic acid, ammonia water and hydrogen peroxide.

3. Used as an analytical reagent and also used in the preparation of high-purity fluorides

4. It is a necessary source of fluorine for fluoride salts, fluorine refrigerants, fluorine plastics, fluorine rubber, fluorine medicines and pesticides

5. It is a raw material for the production of refrigerants "Freon", fluorine-containing resins, organic fluorides and fluorine. In chemical production, it can be used as a catalyst for organic synthesis such as alkylation, polymerization, condensation and isomerization. It is also used to corrode strata when mining certain mineral deposits, as well as to extract rare earth elements and radioactive elements. In the atomic energy industry and nuclear weapons production, it is a raw material for the manufacture of uranium hexafluoride, as well as a raw material for the production of rocket fuel and additives. It can also be used to corrode glass and impregnate wood, etc.

6. Used in the manufacture of organic or inorganic fluorides, such as fluorocarbons, sodium fluoride, aluminum fluoride, uranium hexafluoride and cryolite. It is also used for pickling of stainless steel and non-ferrous metals, engraving and lettering of glass instrument scales, glassware and mirrors, polishing of glassware, frosted bulbs and general bulb processing, desiliconization and purification of metal graphite emulsion, sand removal of metal castings, removal of graphite ash, and manufacture of semiconductors (germanium, silicon). It is also used as a catalyst for dye synthesis and other organic synthesis. It is also used for electroplating, reagents, fermentation, ceramic processing, and the manufacture of fluorine-containing resins and flame retardants.

7. Used for etching glass, pickling metals, and making inorganic fluoride salt products and chemical reagents.

8. Used in atomic energy industry, production of elemental fluorine and fluoride, as catalyst, fluoridation agent, etc. Used in the manufacture of organic or inorganic fluoride, also used in stainless steel, non-ferrous metal pickling, glassware frosting and pickling, frosted light bulb treatment, etc.

9. Determination of silicon dioxide, manufacture of fluoride, copper cleaner, metallurgical phase analysis, silicon compound analysis.

Production method

1. Sulfuric acid method: Mix the dried fluorite powder and sulfuric acid in a ratio of 1: (1.2-1.3) and send them into a rotary reactor for reaction. The gas phase temperature in the furnace is controlled at 280℃±10℃. The gas after the reaction enters the crude distillation tower to remove most of the sulfuric acid, water and fluorite powder. The tower bottom temperature is controlled at 100-110℃ and the tower top temperature is 35-40℃. The crude hydrogen fluoride gas is then condensed into liquid through a degassing tower. The tower bottom temperature is controlled at 20-23℃ and the tower top temperature is -8℃±1℃. Then it enters a distillation tower for distillation. The tower bottom temperature is controlled at 30-40℃ and the tower top temperature is 19.6℃±0.5℃. The refined hydrogen fluoride is absorbed by water to obtain hydrofluoric acid product. Its CaF2+H2SO4→2HF+CaSO4

2. Sulfuric acid method: The hydrogen fluoride generated by the decomposition of fluorite by sulfuric acid is crudely distilled, degassed, and then distilled to obtain anhydrous hydrofluoric acid. Its CaF2+H2SO4→2HF+CaSO4

3. Refining and purification method: Industrial-grade hydrofluoric acid is purified by distillation, impurities are removed by condensation separation, and dust particles are removed by microporous filter membrane to obtain colorless and transparent electronic-grade hydrofluoric acid.