UNUSUAL AMONG ACIDS
The Soviet Urals are rich. In the bowels of its mountains, there are many various minerals. On the right bank of the Miass River, which flows through the Zlatoust district of the Ural region, the low Ilmensky mountains stretch. Nature has created a kind of pantry of rare minerals in the Ilmensky mountains: topaz, ilmenite and others. Like flowers in spring, multi-colored crystals of fluorspar sparkle in the sun - a mineral that has the most diverse colors. In its crystals, the whole spectrum of colors is represented - from red to purple. But fluorspar is remarkable not only for the richness of its coloring. From it, by treatment with concentrated sulfuric acid, a remarkable substance is obtained - hydrogen fluoride, an aqueous solution of which is called hydrofluoric acid.
Hydrofluoric acid has properties that other acids do not have. All acids are usually stored in glass containers. But as soon as a small drop of hydrofluoric acid gets on the wall of a glassware, a deep shell immediately forms on it, and with a more or less prolonged exposure, a hole.
Hydrofluoric acid easily corrodes glass, so it is usually stored in ebonite, lead or paraffin-coated glass vessels.
The property of hydrofluoric acid to corrode glass is used in the processing of glass products. The finest patterns and a wide variety of drawings are applied "on glass using hydrogen fluoride or its aqueous solution - hydrofluoric acid. To do this, the surface of the glass is covered with a thin layer of paraffin, on which the desired inscription or drawing is made with a sharp object , after which the surface is wetted with hydrofluoric acid or placed in a stream of gaseous hydrogen fluoride.When treating glass with hydrofluoric acid, the pattern is transparent, and when using gaseous hydrogen fluoride - opaque.
Hydrofluoric acid is used in glass polishing to remove irregularities on the surface of glass products. The glass surface is thoroughly ground and then placed in a solution consisting of a mixture of sulfuric and hydrofluoric acids.
Anhydrous hydrogen fluoride is a liquid with a boiling point of +19.5°C and a freezing point of -92°C. It is a very strong drying agent. There are no chemical compounds that cannot be drunk with the help of hydrogen fluoride, and water can not be separated from hydrofluoric acid only by electrolysis.
Anhydrous hydrogen fluoride is a strong acid. However, its aqueous solution - hydrofluoric acid - cannot be classified as strong acids - this is a feature that is not found in any of the other acids.
A very valuable property of hydrogen fluoride, due to which it has found wide application in industry, is its pronounced catalytic - accelerating - effect on many chemical reactions. Of the processes catalyzed by hydrogen fluoride, the most important is the chemical process of processing hydrocarbons in the production of motor fuel.
Fluoric acid has unusual properties due to the chemical element fluorine, which is part of its composition. The oxidizing ability of fluorine is much higher than that of oxygen. Combustible materials - wood, rubber and others - when they are introduced into the atmosphere of fluorine, they immediately flare up and burn out. Fluorine interacts with almost all metals at ordinary temperatures; the only exceptions are gold and platinum. But when heated, and eni react with it. Fluorine oxidizes even oxygen. Of all the elements found on earth, fluorine is the
Engineer A. SEREGIN Fig. I. SMOLYANINOVA
The structure of the fluorine atom
I39Ch8 O S N O V V
gives the greatest ability to enter into chemical reactions. Therefore, the name was given to him from the Greek word "fluoros", which in Greek means "destroying".
In its pure form, fluorine was obtained in 1886 by the French chemist Moissan by electrolysis of hydrofluoric acid.
Fluorine is a yellow-green gas, it turns into a liquid at a temperature of -187.9°C, and into a solid -■ at a temperature of -223°C. Gaseous fluorine is 1.31 times heavier than air.
The practical value of this or that substance is determined to a large extent by its prevalence and availability. Fluorine is not a rare element on earth. The earth's crust contains about 0.078®/" in the form of various salts of fluorine. It's about the same. how many elements such as nitrogen, carbon, manganese, chromium and phosphorus are. In terms of prevalence, fluorine ranks thirteenth among other elements.
Of the fluorine compounds found in the earth's crust, the most important is the mineral already known to us - fluorspar - fluorite.
Fluorine is found in plants and animals. Leaves of plants contain from 3 to 14 mg of fluorine per 1 g of dry weight. In human teeth and hair, the fluorine content ranges from 100 to 180 mg per 100 g.
Significant amounts of fluorine contain natural waters. Sea water has, in the form of water-soluble fluoride salts, about 0.3 mg of fluoride per litre. Therefore, 0.3 g of pure fluorine can be obtained from one ton of sea water.
Fluorine compounds are currently widely used both in scientific laboratories and in industrial enterprises.
FLUORINE COMPOUNDS - BUILDING MATERIAL
Organic substances play a huge role in human life. They are used as fuel and food (oil, peat, coal, fruits and cereals of plants, animal fats, etc.) and as a building material (wood, fabrics, rubber, artificial plastic materials, and others). And if the high ability of organic compounds to enter into chemical reactions, in particular their easy oxidizability, is beneficial when they are used as nutrients and fuel, then such properties for a building material are undesirable, since wood products are destroyed, decay, fade fabrics and fade from oxidation. etc.
But as soon as hydrocarbons replace the hydrogen atoms that make up their molecules with fluorine atoms, the resulting compounds - fluorocarbons, while remaining related to organic compounds, acquire qualities that are not characteristic of these compounds. Fluorocarbons, as well as mineral fluorine compounds, are completely unaffected by oxidation. Oyi cannot serve as food for insects and bacteria, as a result of which objects made from fluorine-containing compounds or impregnated with them are inaccessible to decay and the harmful effects of insects, which is especially important for building materials.
Sodium chloride is widely used to impregnate wood. It protects the wood from fungal attack. Sodium fluoride solution is impregnated with railway sleepers, telegraph poles and other building products. The service life of wood treated with sodium fluoride increases several times.
Fluorocarbons are close to noble gases in terms of chemical inertness. This resistance allows them to be used as a material for chemical equipment.
It is known that mineral oils used to lubricate various mechanisms lose their lubricating properties at elevated temperatures, as a result of which
hydrofluoric acid, hydrofluoric acid in dentistry
Hydrofluoric acid(hydrofluoric acid, hydrofluoric acid, hydrofluoric acid) - an aqueous solution of hydrogen fluoride (HF). The industry produces in the form of 40% (more often), as well as 50% and 72% solutions. The name "hydrofluoric acid" comes from fluorspar, from which hydrogen fluoride is obtained.
- 1 Properties
- 1.1 Physical
- 1.2 Chemical
- 2 Technical hydrofluoric acid
- 3 Application
- 4 Toxic properties
- 5 Notes
Properties
Physical
Colorless liquid. The dissolution of hydrogen fluoride in water is accompanied by a rather significant release of heat (59.1 kJ/mol). It is characterized by the formation of an azeotropic mixture containing 38.3% HF and boiling at 112 °C (according to other sources, 37.5% and tbp 109 °C). This azeotropic mixture is ultimately obtained by distillation of both concentrated and dilute acid.
At low temperatures, hydrogen fluoride forms unstable compounds with water of the composition H2O HF, H2O 2HF and H2O 4HF. The most stable of them is the first one (tmelt −35 °C), which should be considered as hydronium fluoride - F. The second is hydronium hydrofluoride.
Chemical
Hydrofluoric acid is an acid of medium strength (the dissociation constant is 6.8 10−4, the degree of dissociation of a 0.1 N solution is 9%). It corrodes glass and other silicate materials, so hydrofluoric acid is stored and transported in polyethylene containers.
The reaction proceeds with the release of gaseous silicon fluoride (SiF4):
It reacts with many metals to form fluorides (lead does not dissolve in hydrofluoric acid, since insoluble fluoride PbF2 forms on its surface; platinum, palladium and gold also do not dissolve), does not affect paraffin, which is used when storing this acid.
Technical hydrofluoric acid
Technical hydrofluoric acid usually contains a number of impurities - Fe, Rb, As, fluorosilic acid H2SiF6, SO2, etc.
For rough cleaning, it is distilled in apparatuses made of platinum or lead, discarding the first portions of the distillate.
To obtain a purer acid, technical acid is converted into potassium hydrofluoride, then it is decomposed by heating, dissolving hydrogen fluoride in distilled water.
Strong hydrofluoric acid (more than 60% HF) can be stored and transported in steel tanks. For storage of hydrofluoric acid and work with it in laboratory conditions, vessels made of Teflon, polyethylene and other plastics are most convenient.
Application
A major consumer of hydrofluoric acid is the aluminum industry.
- A solution of hydrogen fluoride is used for transparent etching of silicate glass (for example, inscriptions - for this, the glass is coated with paraffin, cutting holes for etching). Matte etching is obtained in hydrogen fluoride vapor.
- For silicon etching in the semiconductor industry.
- As part of pickling, pickling and polishing mixtures, solutions for electrochemical processing of stainless steel and special alloys.
- Production of fluorides, silicon fluorides and boron fluorides, organofluorine compounds, as well as corresponding acids (hydrosilicic acid and hydroboric acid), synthetic lubricating oils and plastics.
- For dissolving silicates in various kinds of analyses.
- In the alkylation process, as a catalyst in the reaction of isobutane and olefin.
Toxic properties
Hydrofluoric acid is poisonous. It has a weak narcotic effect. Possible acute and chronic poisoning with changes in the blood and hematopoietic organs, organs of the digestive system, pulmonary edema.
It has a pronounced effect when inhaled, irritating to the skin and mucous membranes of the eyes (causes painful burns and ulceration); skin-resorptive, embryotropic, mutagenic and cumulative action. It has been assigned the second environmental hazard class, while pure hydrogen fluoride belongs to the first hazard class.
When it comes into contact with the skin, at the first moment it does not cause severe pain, it is easily and imperceptibly absorbed, but after a short time it causes swelling, pain, chemical burns and a general toxic effect. Symptoms from exposure to weakly concentrated solutions may appear a day or even more after contact with the skin.
When it enters the blood through the skin, it binds blood calcium and can cause a violation of cardiac activity. Burns with an area of more than 160 cm2 are dangerous due to possible systemic toxic manifestations.
The toxicity of hydrofluoric acid and its soluble salts is presumably due to the ability of free fluoride ions to bind biologically important calcium and magnesium ions into insoluble salts (see Fluoride Poisoning). Therefore, to treat the effects of exposure to hydrofluoric acid, calcium gluconate is often used as a source of Ca2+ ions. Affected areas with hydrofluoric acid burns are washed with water and treated with 2.5% calcium gluconate gel. However, since the acid penetrates the skin, simply rinsing is not enough and a doctor's appointment is necessary for treatment. High efficiency was shown by intra-arterial infusions of calcium chloride.
Maximum Permissible Concentration (MAC) of hydrofluoric acid:
Notes
- The original pronunciation variant "Plavikovaya", recorded in the dictionaries of the 19th (for example, in the dictionary of V. I. Dahl) and the first half of the 20th century, is outdated.
- Dissolution of glass in hydrofluoric acid - video experience in the United Collection of Digital Educational Resources
- GOST 12.1.007-76: System of labor safety standards. Harmful substances
- el Saadi MS, Hall AH, Hall PK, Riggs BS, Augenstein WL, Rumack BH (1989). "Hydrofluoric acid dermal exposure". Vet Hum Toxicol 31 (3): 243–7. PMID 2741315.
- Roblin I, Urban M, Flicoteau D, Martin C, Pradeau D (2006). "Topical treatment of experimental hydrofluoric acid skin burns by 2.5% calcium gluconate". J Burn Care Res 27 (6): 889–94. DOI:10.1097/01.BCR.0000245767.54278.09. PMID 17091088.
- Recommended Medical Treatment for Hydrofluoric Acid Exposure (PDF). Honeywell Specialty Materials. Retrieved May 6, 2009. Archived from the original on February 2, 2012.
- Intra-arterial calcium infusion for hydrofluoric acid burns. NCBI. Retrieved 3 January 2010.
hydrofluoric acid, hydrofluoric acid in dentistry, buy hydrofluoric acid, hydrofluoric acid formula
Hydrofluoric acid information about
Hydrofluoric acid (hydrofluoric acid) is an aqueous solution of hydrogen fluoride (HF). The industry produces in the form of 40% (more often), as well as 50% and 72% solutions. The name "hydrofluoric acid" comes from fluorspar, from which hydrogen fluoride is obtained.
Physical properties
The dissolution of hydrogen fluoride in water is accompanied by a rather significant release of heat (59 kJ/mol). It is characterized by the formation of an azeotropic mixture containing 38.3% HF and boiling at 112 °C (according to other sources, 37.5% and bp 109 °C). Such an azeotropic mixture is ultimately obtained by distillation of both strong and dilute acids.
At low temperatures, hydrogen fluoride forms unstable compounds with water of the composition H2O HF, H2O 2HF and H2O 4HF. The most stable of them is the first one (mp 35 °C), which should be considered as oxonium fluoride - [Н3O]F. The second is oxonium hydrofluoride [H3O].
Chemical properties
This is an acid of medium strength (the dissociation constant is 6.8 104, the degree of dissociation of a 0.1 N solution is 9%). Like hydrogen fluoride, it corrodes glass and other silicate materials, so hydrofluoric acid is stored and transported in polyethylene containers.
The reaction goes according to the equation: SiO2 + 4HF SiF4 + 2H2O
with the release of gaseous silicon fluoride (SiF4).
It reacts with many metals to form fluorides (lead does not dissolve in hydrofluoric acid, since insoluble fluoride PbF2 forms on its surface; platinum and gold also do not dissolve), does not affect paraffin, which is used when storing this acid.
Technical hydrofluoric acid
Technical hydrofluoric acid usually contains a number of impurities - Fe, Pb, As, fluorosilicic acid H2SiF6, SO2), etc.
For rough cleaning, it is distilled in apparatuses made of platinum or lead, discarding the first portions of the distillate.
To obtain a purer acid, technical acid is converted into potassium bifluoride, then it is decomposed by heating, dissolving hydrogen fluoride in distilled water.
Strong hydrofluoric acid (more than 60% HF) can be stored and transported in steel tanks. For storage of hydrofluoric acid and work with it in laboratory conditions, vessels made of Teflon, polyethylene and other plastics are most convenient.
Application
For etching silicate glass (transparent etching in solution, frosted - in hydrofluoric acid vapor)
As part of pickling, pickling and polishing mixtures, solutions for electrochemical processing of stainless steel and special alloys
Obtaining fluorides, silicic fluorides and boron fluorides, as well as the corresponding acids (hydrosilicic acid and hydroboric acid).
Toxic properties
Hydrofluoric acid is highly toxic. It has a weak narcotic effect. Possible acute and chronic poisoning with changes in the blood and hematopoietic organs, organs of the digestive system, pulmonary edema.
It has a pronounced inhalation effect, irritating effect on the skin and mucous membranes of the eyes (causes painful burns and ulceration); skin-resorptive, embryotropic, mutagenic and cumulative action. It has been assigned the second class of environmental hazard.
When it comes into contact with the skin, at the first moment it does not cause severe pain, it is easily and imperceptibly absorbed, but after a short time it causes swelling, pain, chemical burns and a general toxic effect.
Maximum Permissible Concentration (MAC) of hydrofluoric acid:
Application
A solution of hydrogen fluoride is used for transparent etching of glass (for example, inscription, for this the glass is coated with paraffin, cutting holes for etching). Matte etching is obtained in hydrogen fluoride vapor.
A major consumer of hydrofluoric acid is the aluminum industry.
In addition, hydrofluoric acid is used:
For silicon etching in the semiconductor industry
In compositions for pickling cast iron and stainless steels
For production of organofluorine compounds, inorganic fluorides, synthetic lubricating oils and plastics
For dissolving silicates in various kinds of analyses.
Physical properties
The dissolution of hydrogen fluoride in water is accompanied by a rather significant release of heat (59 kJ/mol). It is characterized by the formation of an azeotropic mixture containing 38.3% HF and boiling at 112 °C (according to other sources, 37.5% and bp t 109 °C). Such an azeotropic mixture is ultimately obtained by distillation of both strong and dilute acids.
At low temperatures, hydrogen fluoride forms unstable compounds with water of the composition H 2 O HF, H 2 O 2HF and H 2 O 4HF. The most stable of them is the first one (t pl −35 °C), which should be considered as oxonium fluoride - [Н 3 O]F. The second is oxonium hydrofluoride [H 3 O].
Chemical properties
The reaction goes according to the equation:
with the release of gaseous silicon fluoride (SiF 4).
It reacts with many metals to form fluorides (lead does not dissolve in hydrofluoric acid, since insoluble fluoride PbF 2 forms on its surface; platinum and gold also do not dissolve), does not affect paraffin, which is used when storing this acid.
Technical hydrofluoric acid
Technical hydrofluoric acid usually contains a number of impurities - Fe, Rb, As, fluorosilicic acid H 2 SiF 6 , SO 2), etc.
For rough cleaning, it is distilled in apparatuses made of platinum or lead, discarding the first portions of the distillate.
To obtain a purer acid, technical acid is converted into potassium hydrofluoride, then it is decomposed by heating, dissolving hydrogen fluoride in distilled water.
Strong hydrofluoric acid (more than 60% HF) can be stored and transported in steel tanks. For storage of hydrofluoric acid and work with it in laboratory conditions, vessels made of Teflon, polyethylene and other plastics are most convenient.
Application
A major consumer of hydrofluoric acid is the aluminum industry.
- A solution of hydrogen fluoride is used for transparent etching of silicate glass (for example, inscription, for this the glass is coated with paraffin, cutting holes for etching). Matte etching is obtained in hydrogen fluoride vapor.
- For silicon etching in the semiconductor industry.
- As part of pickling, pickling and polishing mixtures, solutions for electrochemical processing of stainless steel and special alloys.
- Obtaining fluorides, silicofluorides and boron fluorides, organofluorine compounds, as well as the corresponding acids (hydrosilicic acid and hydroboric acid), synthetic lubricating oils and plastics.
- For dissolving silicates in various kinds of analyses.
Toxic properties
It has a pronounced inhalation effect, irritating effect on the skin and mucous membranes of the eyes (causes painful burns and ulceration); skin-resorptive, embryotropic, mutagenic and cumulative action. It has been assigned the second class of environmental hazard.
When it comes into contact with the skin, at the first moment it does not cause severe pain, it is easily and imperceptibly absorbed, but after a short time it causes swelling, pain, chemical burns and general toxic effects. Symptoms from exposure to weakly concentrated solutions may appear a day or even more after contact with the skin.
There are practically no specific antidotes, therefore, when a lethal dose of hydrogen fluoride is absorbed by the skin, a person can live for several days (on drugs), but without hope of salvation.
Maximum Permissible Concentration (MAC) of hydrofluoric acid:
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See what "Hydrofluoric acid" is in other dictionaries:
- (hydrofluoric acid) a solution of hydrogen fluoride in water, a relatively weak acid. It interacts with silicate materials, which is used for etching glass, removing sand from metal castings ... Big Encyclopedic Dictionary
HYDROFLUORIC ACID- (H2F2) the same as hydrofluoric (see) ... Great Polytechnic Encyclopedia
hydrofluoric acid- - [A.S. Goldberg. English Russian Energy Dictionary. 2006] Topics energy in general EN hydrofluoric acid … Technical Translator's Handbook
Same as hydrofluoric acid. * * * HYDROFLUORIC ACID HYDROFLUORIC ACID (hydrofluoric acid), a solution of hydrogen fluoride in water, a relatively weak acid. Interacts with silicate materials, which is used for ... ... encyclopedic Dictionary
hydrofluoric acid- vandenilio fluoridas statusas T sritis chemija formulė HF atitikmenys: engl. fluorohydric acid; fluoric acid; fluorohydrogen acids; hydrofluoric acid; hydrogen fluoride eng. hydrogen fluoride; hydrofluoric acid; hydrofluoric acid; ... ... Chemijos terminų aiskinamasis žodynas
Hydrofluoric acid, aqueous hydrogen fluoride (See Hydrogen Fluoride) HF; Hydrogen fluoride is miscible with water in any ratio. The azeotropic mixture contains 38.26% HF, tkp 112°C (750 mmHg), density 1.138 g/cm3. F. to ... Great Soviet Encyclopedia
A solution of hydrogen fluoride in water. F. to. apply to production of aluminum trifluoride, arts. cryolite, uranium tetrafluoride and other inorganic. fluorides, for metal, glass and PP etching, for glass polishing. Obsolete name tech. F. to. ... ... Big encyclopedic polytechnic dictionary
Same as hydrofluoric acid... Natural science. encyclopedic Dictionary
hydrofluoric acid- hydrofluoric acid … Dictionary of chemical synonyms I
- (hydrofluoric acid), p p hydrogen fluoride in water. Obsolete name hydrofluoric to ta. There can be 3 compounds in the HF H2O system: H2O … Chemical Encyclopedia
All water-soluble fluorides are toxic.
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| General | |
| Systematic Name |
hydrogen fluoride |
| Traditional names | hydrofluoric acid |
| Chem. formula | HF |
| Physical properties | |
| State | colorless liquid |
| Molar mass | 20.0063 g/mol |
| Density | 1,258 (70 %) |
| Thermal Properties | |
| T. melt. | −75 (70 %) |
| T. kip. | 85.8 (70%) °C |
| T. rev. | non-flammable °C |
| Chemical properties | |
| pK a | 3,17 |
| Solubility in water | mixed up |
| Classification | |
| Reg. CAS number | 7664-39-3 |
| Reg. EC number | 231-634-8 |
| RTECS | MW7875000 |
| Safety | |
| Toxicity | |
| Data is based on standard conditions (25 °C, 100 kPa) unless otherwise noted. | |
Properties
Physical
A colorless, mobile liquid with a pungent odor and a burning "acetic" taste. The dissolution of hydrogen fluoride in water is accompanied by a rather significant release of heat (59.1 kJ/mol). It is characterized by the formation of an azeotropic mixture containing 38.6% HF and boiling at 114 °C (according to other sources, 37.5% and bp t 109 °C). This azeotropic mixture is ultimately obtained by distillation of both concentrated and dilute acid.
At low temperatures, hydrogen fluoride forms unstable compounds with water of the composition H 2 O HF, H 2 O 2HF and H 2 O 4HF. The most stable of them is the first one (t pl −35 °C), which should be considered as hydronium fluoride - [Н 3 O]F. The second is hydronium hydrofluoride [H 3 O].
Chemical
Hydrofluoric acid is a rather weak acid (of medium strength) (the dissociation constant is 6.8⋅10 −4, the degree of dissociation of a 0.1 N solution is 9%), however, it corrodes glass and other silicate materials, therefore hydrofluoric acid is stored and transported in polyethylene container.
The reaction proceeds with the release of gaseous silicon fluoride (SiF 4):
N a 2 O ⋅ C a O ⋅ 6 S i O 2 + 28 H F → N a 2 S i F 6 + C a S i F 6 + 4 S i F 4 + 14 H 2 O (\displaystyle (\mathsf ( Na_(2)O\cdot CaO\cdot 6SiO_(2)+28HF\rightarrow Na_(2)SiF_(6)+CaSiF_(6)+4SiF_(4)\uparrow +14H_(2)O))).
Reacts with many metals to form fluorides (lead does not dissolve in hydrofluoric acid, since insoluble fluoride PbF 2 forms on its surface; platinum, palladium and gold also do not dissolve), does not affect paraffin, which is used when storing this acid.
Technical hydrofluoric acid
Technical hydrofluoric acid usually contains a number of impurities - Fe, Rb, As, hydrofluorosilic acid H 2 SiF 6, SO 2, etc.
For rough cleaning, it is distilled in apparatuses made of platinum or lead, discarding the first portions of the distillate.
To obtain a purer acid, technical acid is converted into potassium hydrofluoride, then it is decomposed by heating, dissolving hydrogen fluoride in distilled water.
Strong hydrofluoric acid (over 60% HF) can be stored and transported in steel containers, but corrodes glass. Storage and handling of hydrofluoric acid in the laboratory requires vessels made of Teflon, polyethylene, and other plastics.
Application
A major consumer of hydrofluoric acid is the aluminum industry.
- A solution of hydrogen fluoride is used for transparent etching of silicate glass (for example, inscriptions - for this, the glass is coated with paraffin, cutting holes for etching). Matte etching is obtained in hydrogen fluoride vapor.
- For silicon etching in the semiconductor industry.
- As part of pickling, pickling and polishing mixtures, solutions for electrochemical processing of stainless steel and special alloys.
- Obtaining fluorides, silicofluorides and boron fluorides, organofluorine compounds, as well as the corresponding acids (hydrosilicic acid and hydroboric acid), synthetic lubricating oils and plastics.
- For dissolving silicates in various kinds of analyses.
- In the alkylation process, as a catalyst in the reaction of isobutane and olefin.
Toxic properties
poisonous. Possible acute and chronic poisoning with changes in the blood and blood-forming organs, organs of the digestive system, pulmonary edema.
It has a pronounced effect when inhaled, irritating to the skin and mucous membranes of the eyes (causes painful burns and ulceration); skin-resorptive, embryotropic, mutagenic and cumulative action. She was assigned the second class of environmental hazard; pure hydrogen fluoride also belongs to the second hazard class.
When it comes into contact with the skin, at the first moment it does not cause severe pain, it is easily and imperceptibly absorbed, but after a short time it causes swelling, pain, chemical burns and general toxic effects. Symptoms from exposure to weakly concentrated solutions may appear a day or even more after contact with the skin.
When it enters the blood through the skin, it binds blood calcium and can cause a violation of cardiac activity. Burns with an area of more than 160 cm 2 are dangerous with possible systemic toxic manifestations.
The toxicity of hydrofluoric acid and its soluble salts is presumably due to the ability of free fluorine ions to bind biologically important calcium and magnesium ions into insoluble salts ( fluoride poisoning). Therefore, to treat the effects of exposure to hydrofluoric acid, it is often used
