Hydrochloric acid (hydrochloric acid, an aqueous solution of hydrogen chloride), known as HCl, is a caustic chemical compound. Since ancient times, people have been using this colorless liquid for various purposes, which emits a light smoke in the open air.

Properties of a chemical compound

HCl is used in various areas of human activity. It dissolves metals and their oxides, is absorbed in benzene, ether and water, and does not destroy fluoroplastic, glass, ceramics and graphite. Its safe use is possible when stored and operated in the correct conditions, in compliance with all safety standards.

Chemically pure (CP) hydrochloric acid is formed during gaseous synthesis from chlorine and hydrogen, giving hydrogen chloride. It is absorbed in water, resulting in a solution containing 38-39% HCl at +18 C. An aqueous solution of hydrogen chloride is used in various areas of human activity. The price of chemically pure hydrochloric acid is variable and depends on many components.

Areas of application of aqueous hydrogen chloride solution

The use of hydrochloric acid has become widespread due to its chemical and physical properties:

• in metallurgy, in the production of manganese, iron and zinc, technological processes, metal purification;
• in galvanoplasty - during etching and pickling;
• in the production of soda water to regulate acidity, in the production of alcoholic beverages and syrups in the food industry;
• for leather processing in light industry;
• when purifying non-drinking water;
• for optimization of oil wells in the oil industry;
• in radio engineering and electronics.

Hydrochloric acid (HCl) in medicine

The most famous property of hydrochloric acid solution is the equalization of the acid-base balance in the human body. Low stomach acidity is treated with a weak solution or drugs. This optimizes the digestion of food and helps fight germs and bacteria that penetrate from the outside. HCl hydrochloric acid helps normalize low levels of gastric acidity and optimizes protein digestion.

Oncology uses HCl to treat tumors and slow down their progression. Hydrochloric acid preparations are prescribed for the prevention of stomach cancer, rheumatoid arthritis, diabetes, asthma, urticaria, cholelithiasis and others. In folk medicine, hemorrhoids are treated with a weak acid solution.

You can find out more about the properties and types of hydrochloric acid.

- (HCl), an aqueous solution of hydrogen chloride, a colorless gas with a pungent odor. It is obtained by the action of sulfuric acid on table salt, as a by-product of the chlorination of hydrocarbons, or by the reaction of hydrogen and chlorine. Hydrochloric acid is used for... ... Scientific and technical encyclopedic dictionary

Hydrochloric acid- – HCl (HC) (hydrochloric acid, hydrochloric acid, hydrogen chloride) is a solution of hydrogen chloride (HCl) in water, an antifreeze additive. It is a colorless liquid with a pungent odor, without suspended particles.… … Encyclopedia of terms, definitions and explanations of building materials

HYDROCHLORIC ACID- (hydrochloric acid) a solution of hydrogen chloride in water; strong acid. Colorless liquid that fumes in air (technical hydrochloric acid is yellowish due to impurities of Fe, Cl2, etc.). Maximum concentration (at 20.C) 38% by weight,... ... Big Encyclopedic Dictionary

HYDROCHLORIC ACID- (Acidum muriaticum, Acid, hydrochloricum), a solution of hydrogen chloride (HC1) in water. In nature, it is found in the water of certain sources of volcanic origin, and is also found in gastric juice (up to 0.5%). Hydrogen chloride can be obtained... Great Medical Encyclopedia

HYDROCHLORIC ACID- (hydrochloric acid, hydrochloric acid) a strong monobasic volatile acid with a pungent odor, an aqueous solution of hydrogen chloride; the maximum concentration is 38% by weight, the density of such a solution is 1.19 g/cm3. Used in... ... Russian encyclopedia of labor protection

HYDROCHLORIC ACID- (hydrochloric acid) HCl, an aqueous solution of hydrogen chloride, a strong monobasic acid, volatile, with a pungent odor; impurities of iron and chlorine color it yellowish. Concentrated S. K. that goes on sale contains 37%... ... Big Polytechnic Encyclopedia

hydrochloric acid- noun, number of synonyms: 1 acid (171) ASIS Dictionary of Synonyms. V.N. Trishin. 2013… Synonym dictionary

HYDROCHLORIC ACID Modern encyclopedia

Hydrochloric acid- HORRICALS ACID, an aqueous solution of hydrogen chloride HCl; a liquid that fumes in air and has a pungent odor. Hydrochloric acid is used to produce various chlorides, pickling metals, processing ores, in the production of chlorine, soda, rubbers, etc.... ... Illustrated Encyclopedic Dictionary

hydrochloric acid- (hydrochloric acid), a solution of hydrogen chloride in water; strong acid. Colorless, “smoking” liquid in air (technical hydrochloric acid is yellowish due to impurities of Fe, Cl2, etc.). Maximum concentration (at 20°C) 38% by weight,... ... encyclopedic Dictionary

Tank with hydrochloric acid

One of the strong monobasic acids and is formed when gas dissolves hydrogen chloride(HCl) in water is a clear, colorless liquid with a characteristic odor of chlorine. Dilute hydrochloric acid(as well as phosphorus) is often used to remove oxides when soldering metals.

Sometimes the gaseous compound HCl is mistakenly called hydrochloric acid. HCl is a gas that when dissolved in water forms hydrochloric acid.

Hydrogen chloride- a colorless gas with a sharp suffocating odor of chlorine. It turns into a liquid state at -84 0 C, and at -112 0 C it turns into a solid state.

Hydrogen chloride very soluble in water. So at 0 0 C, 500 liters of hydrogen chloride dissolve in 1 liter of water.
In its dry state, hydrogen chloride gas is quite inert, but it can already interact with some organic substances, for example with acetylene (a gas that is released when carbide is lowered into water).

Chemical properties of hydrochloric acid

Chemical reaction with metals:
2HCl + Zn = ZnCl 2 + H 2 - salt is formed (in this case, a clear solution of zinc chloride) and hydrogen
- chemical reaction with metal oxides:
2HCl + CuO = CuCl 2 + H 2 O - salt is formed (in this case, a solution of green copper chloride salt) and water
- chemical reaction with bases and alkalis (or neutralization reaction)
HCl + NaOH = NaCl + H 2 O - neutralization reaction - salt is formed (in this case, a clear solution of sodium chloride) and water.
- chemical reaction with salts (for example, with chalk CaCO 3):
HCl + CaCO 3 = CaCl 2 + CO 2 + H 2 O - carbon dioxide, water and a clear solution of calcium chloride CaCl 2 are formed.

Obtaining hydrochloric acid

Hydrochloric acid are obtained using a chemical reaction of the compound:

H 2 + Cl 2 = HCl - the reaction occurs at elevated temperatures

And also in the interaction of table salt and concentrated sulfuric acid:

H 2 SO 4 (conc.) + NaCl = NaHSO 4 + HCl

In this reaction, if the substance NaCl is in solid form, then HCl is a gas hydrogen chloride, which when dissolved in water forms hydrochloric acid

There are complex chemical substances that are similar in chemical structure to hydrochloric acid, but contain from one to four oxygen atoms in the molecule. These substances can be called oxygen-containing acids. With an increase in the number of oxygen atoms, the stability of the acid and its oxidizing ability increase.

TO oxygen-containing acids the following:

• hypochlorous (HClO),
• chloride (HClO 2),
• chloric acid (HClO 3),
• chlorine (HClO 4).

Each of these chemical complexes has all properties of acids and is capable of forming salts. Hypochlorous acid(HClO) forms hypochlorites, for example, the compound NaClO is sodium hypochlorite. Hypochlorous acid itself is formed when chlorine is dissolved in cold water by a chemical reaction:

H 2 O + Cl 2 = HCl + HClO,

As you can see, in this reaction two acids are formed at once - salt HCl and hypochlorous HClO. But the latter is an unstable chemical compound and gradually turns into hydrochloric acid;

Chloride HClO2 forms chlorites, salt NaClO 2 - sodium chlorite;
hypochlorous(HClO3) - chlorates, compound KClO 3, - potassium chlorate (or Berthollet's salt) - by the way, this substance is widely used in the manufacture of matches.

And finally, the strongest known monobasic acid - chlorine(HClO 4) - colorless, fuming in air, highly hygroscopic liquid - forms perchlorates, for example, KClO 4 - potassium perchlorate.

Salts formed hypochlorous HClO and chloride HClO 2 acids are unstable in the free state and are strong oxidizing agents in aqueous solutions. But the salts formed hypochlorous HClO 3 and chlorine HClO 4 with acids based on alkali metals (for example, Berthollet salt KClO 3) are quite stable and do not exhibit oxidizing properties.

Hydrochloric acid is an inorganic substance, a monobasic acid, one of the strongest acids. Other names are also used: hydrogen chloride, hydrochloric acid, hydrochloric acid.

Properties

Acid in its pure form is a colorless and odorless liquid. Industrial acid usually contains impurities that give it a slightly yellowish tint. Hydrochloric acid is often called “fuming” because it emits hydrogen chloride vapors, which react with moisture in the air and form acid fog.

Very soluble in water. At room temperature, the maximum possible hydrogen chloride content by weight is 38%. An acid concentration greater than 24% is considered concentrated.

Hydrochloric acid actively reacts with metals, oxides, hydroxides, forming salts - chlorides. HCl reacts with salts of weaker acids; with strong oxidizing agents and ammonia.

To determine hydrochloric acid or chlorides, a reaction with silver nitrate AgNO3 is used, which results in the formation of a white cheesy precipitate.

Safety precautions

The substance is very caustic, corrodes skin, organic materials, metals and their oxides. When exposed to air, it releases hydrogen chloride vapors, which cause suffocation, burns to the skin, mucous membranes of the eyes and nose, damage the respiratory system, and destroy teeth. Hydrochloric acid belongs to substances of the 2nd degree of danger (highly dangerous), the maximum permissible concentration of the reagent in the air is 0.005 mg/l. You can work with hydrogen chloride only in filter gas masks and protective clothing, including rubber gloves, an apron, and safety shoes.

When acid spills, wash it off with plenty of water or neutralize it with alkaline solutions. Those affected by acid should be taken out of the danger area, rinse their skin and eyes with water or soda solution, and call a doctor.

The chemical reagent can be transported and stored in glass, plastic containers, as well as in metal containers coated on the inside with a rubber layer. The container must be hermetically sealed.

Receipt

On an industrial scale, hydrochloric acid is produced from hydrogen chloride (HCl) gas. Hydrogen chloride itself is produced in two main ways:
- exothermic reaction of chlorine and hydrogen - thus obtaining a high-purity reagent, for example, for the food industry and pharmaceuticals;
- from accompanying industrial gases - acid based on such HCl is called exhaust gas.

This is interesting

It was hydrochloric acid that nature “entrusted” with the process of breaking down food in the body. The concentration of acid in the stomach is only 0.4%, but this is enough to digest a razor blade in a week!

Acid is produced by the cells of the stomach itself, which is protected from this aggressive substance by the mucous membrane. However, its surface is renewed daily to restore damaged areas. In addition to participating in the process of digesting food, acid also performs a protective function, killing pathogens that enter the body through the stomach.

Application

- In medicine and pharmaceuticals - to restore the acidity of gastric juice in case of insufficiency; for anemia to improve the absorption of iron-containing drugs.
— In the food industry it is a food additive, acidity regulator E507, and also an ingredient in seltzer (soda) water. Used in the production of fructose, gelatin, citric acid.
- In the chemical industry - the basis for the production of chlorine, soda, monosodium glutamate, metal chlorides, for example zinc chloride, manganese chloride, ferric chloride; synthesis of organochlorine substances; catalyst in organic syntheses.
— Most of the hydrochloric acid produced in the world is consumed in metallurgy for cleaning workpieces from oxides. For these purposes, an inhibited industrial acid is used, which contains special reaction inhibitors (moderators), due to which the reagent dissolves oxides, but not the metal itself. Metals are also etched with hydrochloric acid; clean them before tinning, soldering, galvanizing.
— Treat the leather before tanning.
— In the mining industry it is in demand for cleaning boreholes from sediments, for processing ores and rock formations.
— In laboratory practice, hydrochloric acid is used as a popular reagent for analytical research and for cleaning vessels from difficult-to-remove contaminants.
— Used in the rubber, pulp and paper industries, and in ferrous metallurgy; for cleaning boilers, pipes, equipment from complex deposits, scale, rust; for cleaning ceramic and metal products.

Hydrochloric acid (H Cl)hazard class 3

(concentrated hydrochloric acid)

Colorless, transparent, aggressive, non-flammable liquid with a pungent odor of hydrogen chloride. Represents 36% ( concentrated) a solution of hydrogen chloride in water. Heavier than water. It boils at a temperature of +108.6 0 C, and hardens at a temperature of –114.2 0 C. It dissolves well in water in all proportions, “smoke” in air due to the formation of hydrogen chloride with water vapor and fog droplets. Interacts with many metals, metal oxides and hydroxides, phosphates and silicates. When interacting with metals, it releases a flammable gas (hydrogen); when mixed with other acids, it causes spontaneous combustion of some materials. Destroys paper, wood, fabrics. Causes burns upon contact with skin. Exposure to hydrochloric acid fog, which is formed as a result of the interaction of hydrogen chloride with water vapor in the air, causes poisoning.

Hydrochloric acid is used in chemical synthesis, for processing ores, pickling metals. It is obtained by dissolving hydrogen chloride in water. Technical hydrochloric acid is produced with a strength of 27.5-38% by weight.

Hydrochloric acid is transported and stored in rubberized (coated with a layer of rubber) metal railway and automobile tanks, containers, cylinders, which are its temporary storage. Typically, hydrochloric acid is stored in above-ground cylindrical vertical rubberized tanks (volume 50-5000 m3) at atmospheric pressure and ambient temperature or in 20-liter glass bottles. Maximum storage volumes 370 tons.

Maximum permissible concentration (MPC) in the air inhabited items is 0.2 mg/m 3 in the air of the working area of ​​industrial premises 5 mg/m3. At a concentration of 15 mg/m3, the mucous membranes of the upper respiratory tract and eyes are affected, a sore throat, hoarseness, cough, runny nose, shortness of breath, and difficulty breathing appear. At concentrations of 50 mg/m 3 and above, bubbling breathing, sharp pain in the chest and in the stomach, vomiting, spasm and swelling of the larynx, and loss of consciousness occur. Concentrations of 50-75 mg/m 3 are difficult to tolerate. A concentration of 75-100 mg/m3 is intolerable. A concentration of 6400 mg/m 3 within 30 minutes is lethal. The maximum permissible concentration when using industrial and civil gas masks is 16,000 mg/m 3 .

When eliminating accidents, associated with a spill of hydrochloric acid, it is necessary to isolate the danger zone, remove people from it, stay to the windward side, and avoid low places. Directly at the accident site and in contamination zones with high concentrations at a distance of up to 50 m from the spill site, work is carried out in insulating gas masks IP-4M, IP-5 (using chemically bound oxygen) or breathing apparatus ASV-2, DASV (using compressed air ), KIP-8, KIP-9 (on compressed oxygen) and skin protection products (L-1, OZK, KIH-4, KIH-5). At a distance of more than 50 m from the source, where the concentration sharply decreases, skin protective equipment need not be used, and for respiratory protection, industrial gas masks with boxes of brands B, BKF, as well as civilian gas masks GP-5, GP-7, PDF-2D are used , PDF-2Sh complete with an additional cartridge DPG-3 or respirators RPG-67, RU-60M with a box of brand V.

Due to the fact that hydrochloric acid "smoke" in the air with the formation droplets of fog interacting hydrogen chloride with water vapor, the presence in the air is determined hydrogen chloride.

The presence of hydrogen chloride is determined:

In the air of an industrial zone with an OKA-T-N gas analyzer Cl , gas alarm IGS-98-N Cl , universal gas analyzer UG-2 with a measurement range of 0-100 mg/m 3 , gas detector of industrial chemical emissions GPHV-2 in the range of 5-500 mg/m 3 .

In open space – with SIP “CORSAR-X” devices.

Indoors – SIP “VEGA-M”

Neutralizes hydrochloric acid and hydrogen chloride vapors the following alkaline solutions:

5% aqueous solution of caustic soda (for example, 50 kg of caustic soda per 950 liters of water);

5% aqueous solution of soda powder (for example, 50 kg of soda some powder for 950 liters of water);

5% aqueous solution of slaked lime (for example, 50 kg of slaked lime per 950 liters of water);

5% water solution of caustic soda (for example, 50 kg of caustic soda per 950 liters of water);

In the event of a hydrochloric acid spill and the absence of an embankment or pan, the spill site is fenced off with an earthen rampart, hydrogen chloride vapor is precipitated by placing a water curtain (water consumption is not standardized), the spilled acid is neutralized to safe concentrations with water (8 tons of water per 1 ton of acid) in compliance with all measures precautions or a 5% aqueous solution of alkali (3.5 tons of solution per 1 ton of acid) and neutralize 5% aqueous solution of alkali (7.4 tons of solution per 1 ton of acid).

To spray water or solutions, watering and fire trucks, auto-filling stations (ATs, PM-130, ARS-14, ARS-15), as well as hydrants and special systems available at chemically hazardous facilities, are used.

To dispose of contaminated soil at the site of a hydrochloric acid spill, the surface layer of soil is cut off to the depth of contamination, collected and transported for disposal using earthmoving vehicles (bulldozers, scrapers, motor graders, dump trucks). The cut areas are covered with a fresh layer of soil and washed with water for control purposes.

Leader actions: isolate the danger zone within a radius of at least 50 meters, remove people from it, stay to the windward side, avoid low places. Enter the accident area only in full protective clothing.

Providing first aid:

In the contaminated area: rinse eyes and face generously with water, put on anti-vogaza, urgent withdrawal (removal) from the outbreak.

After evacuating a contaminated area: warming, rest, washing off the acid from exposed skin and clothing with water, washing the eyes abundantly with water, if breathing is difficult, apply heat to the neck area, subcutaneously - 1 ml. 0.1% atropine sulfate solution. Immediate evacuation to a medical facility.