Hydrochloric acid is the formula of the substance. Hydrochloric acid structural chemical formula

GOST 3118-77
(ST SEV 4276-83)

Group L51

STATE STANDARD OF THE USSR UNION

Reagents

HORRIATIC ACID

Specifications

Reagents. Hydrochloric acid.
Specifications

OKP 26 1234 0010 07

Date of introduction 1979-01-01

ENTERED INTO EFFECT by Resolution of the State Committee of Standards of the Council of Ministers of the USSR dated December 22, 1977 N 2994

INSTEAD GOST 3118-67

REISSUE (January 1997) with Amendment No. 1, approved in November 1984 (IUS 2-85)

The validity period was lifted by decision of the Interstate Council for Standardization, Metrology and Certification (IUS 4-94)


This standard applies to the reagent - hydrochloric acid (aqueous solution of hydrogen chloride), which is a colorless liquid with a pungent odor, fuming in air; miscible with water, benzene and ether. The acid density is 1.15-1.19 g/cm.

The technical level indicators established by this standard are provided for the first quality category.

Formula: HCl.

Molecular mass (according to international atomic masses 1971) - 36.46.

The standard fully complies with ST SEV 4276-83.

1. TECHNICAL REQUIREMENTS

1. TECHNICAL REQUIREMENTS

1.1. Hydrochloric acid must be manufactured in accordance with the requirements of this standard according to technological regulations approved in the prescribed manner.

1.2. In terms of chemical indicators, hydrochloric acid must meet the requirements and standards specified in the table.

Note. Hydrochloric acid with the standards indicated in brackets may be produced until 01/01/95.

2a. SAFETY REQUIREMENTS

2a.1. Hydrochloric acid belongs to substances of hazard class III (GOST 12.1.007-76). The maximum permissible concentration of hydrogen chloride in the air of the working area is 5 mg/m. The acid has a cauterizing effect on the mucous membranes and skin, and severely irritates the respiratory tract.

2a.2. When working with the drug, you should use personal protective equipment, as well as observe the rules of personal hygiene and prevent the drug from getting on the mucous membranes, skin, and inside the body.

2a.3. The premises in which work with the drug is carried out must be equipped with general supply and exhaust mechanical ventilation; drug analysis should be carried out in a laboratory fume hood.

2a.4. Hydrochloric acid is a non-flammable and non-flammable liquid.

Section 2a.

2. ACCEPTANCE RULES

2.1. Acceptance rules - according to GOST 3885-73.

2.2. The manufacturer determines the mass fraction of ammonium salts, arsenic and sulfites periodically in every tenth batch.

3. METHODS OF ANALYSIS

3.1a. General instructions for conducting analysis - according to the technical documentation.

(Introduced additionally, Amendment No. 1).

3.1. Samples are taken according to GOST 3885-73. The mass of the average sample must be at least 4500 g (3900 cm).

For analysis, hydrochloric acid is taken with a safe pipette or graduated cylinder in accordance with the density with an error of no more than 1% (by volume).

3.2. Defining Appearance

25 cm of the drug is placed in a cylinder (with a ground stopper) with a capacity of 25 cm and compared in transmitted light along the diameter of the cylinder with the same volume of distilled water (GOST 6709-72) placed in the same cylinder.

The drug must be chemically pure and pure for analysis, colorless, transparent and free of suspended particles.

For a pure preparation, a yellowish color is allowed.

(Changed edition, Amendment No. 1).

3.3. Determination of the mass fraction of hydrochloric acid

3.3.1. Reagents and solutions

Distilled water according to GOST 6709-72.

Mixed indicator, solution of methyl red and methylene blue; prepared according to GOST 4919.1-77.

Sodium hydroxide according to GOST 4328-77, solution concentration (NaOH) = 1 mol/dm (1 N); prepared according to GOST 25794.1-83.

3.3.2. Carrying out analysis

In a conical flask with a capacity of 200-250 cm3, containing 50 cm3 of water, place from 1.2000 to 1.4000 g of the drug, weighed using a Lunge pipette, and mix thoroughly. Add 0.2 cm of mixed indicator solution and titrate with sodium hydroxide solution until the violet-red color changes to green.

3.3.3. Processing the results

The mass fraction of hydrochloric acid () in percent is calculated using the formula

where is the volume of sodium hydroxide solution with a concentration of exactly 1 mol/dm3, used for titration, cm;

0.03646 - mass of hydrogen chloride corresponding to 1 cm of sodium hydroxide solution with a concentration of exactly 1 mol/dm, g;

- weight of the drug sample, g.

The result of the analysis is taken as the arithmetic mean of two parallel determinations, the permissible differences between which at a confidence probability = 0.95 should not exceed 0.2%.

It is allowed to determine the mass fraction of hydrochloric acid with methyl orange or methyl red.

In case of disagreement in the assessment of the mass fraction of hydrochloric acid, the analysis is carried out with a mixed indicator.

(Changed edition, Amendment No. 1)

3.4. Determination of the mass fraction of the residue after calcination (in the form of sulfates) is carried out according to ST SEV 434-77*. In this case, 200 g (170 cm) of the drug for the norm of 0.0005% and 100 g (85 cm) of the drug for the norm of 0.001; 0.002 and 0.005% are placed in a platinum or quartz cup, pre-calcined to constant mass and weighed with an error of no more than 0.0002 g, evaporated in a water bath in portions of up to 1-2 cm, then 0.1-0.5 cm of sulfuric acid is added ( GOST 4204-77). Next, the determination is carried out according to ST SEV 434-77*.

(Changed edition, Amendment No. 1).
_______________
* GOST 27184-86 is valid. - Note "CODE".

3.5. Determination of the mass fraction of sulfites

3.5.1. Reagents and solutions

Distilled water, not containing oxygen; prepared according to GOST 4517-87.

Iodine according to GOST 4159-79, solution concentration (1/2 J) = 0.01 mol/dm (0.01 N), freshly prepared; prepared according to GOST 25794.2-83.

Potassium iodide according to GOST 4232-74, 10% solution; prepared according to GOST 4517-87.

Hydrochloric acid according to this standard.

Soluble starch according to GOST 10163-76, 0.5% solution, freshly prepared.

3.5.2. Carrying out analysis

Place 400 cm of water in a conical flask with a capacity of 500 cm, add 1 cm of potassium iodide solution, 5 cm of hydrochloric acid and 2 cm of starch solution.

The solution is stirred and iodine solution is added dropwise until a bluish color appears. Half of the resulting solution is placed in another conical flask with a capacity of 500 cm3.

100 g (85 cm) of the analyzed drug is placed in one of the flasks in portions with stirring and cooling in an ice water bath, and the same amount of water is added to the other (reference solution).

The color of solutions is compared in transmitted light against the background of milk glass.

If the analyzed solution turns out to be colorless or its color is weaker than the color of the reference solution, then the drug contains an admixture of a reducing agent. In this case, the solution is immediately titrated from a microburette with an iodine solution until the initial bluish color

3.5.1, 3.5.2. (Changed edition, Amendment No. 1).

3.5.3. Processing the results

The mass fraction of sulfites () in percent is calculated using the formula

where is the volume of iodine solution with a concentration of exactly 0.01 mol/dm3 used for titration, cm;

0.00040 - mass of sulfites corresponding to 1 cm of iodine solution with a concentration of exactly 0.01 mol/dm, g.

The result of the analysis is taken as the arithmetic mean of two parallel determinations, the permissible differences between which, at a confidence probability = 0.95, should not exceed 20% relative to the calculated concentration.

(Introduced additionally, Amendment No. 1).

3.6. Determination of the mass fraction of sulfates

The determination is carried out according to GOST 10671.5-74. In this case, 10 g (8.5 cm) of the drug is placed in a porcelain or platinum cup, 2 cm of a 1% solution of sodium carbonate (GOST 83-79) is added, carefully mixed and evaporated to dryness in a water bath, the dry residue is dissolved in water and transfer the solution to a conical flask with a capacity of 50 cm (with a 25 cm mark), bring the volume of the solution to the mark with water and mix. If the solution is cloudy, it is filtered through a dense ashless filter, thoroughly washed with hot water. Next, the determination is carried out using the phototurbidimetric or visual nephelometric method (method 1).

The drug is considered to comply with the requirements of this standard if the mass of sulfates does not exceed:

for the drug chemically pure - 0.020 mg;

for the drug pure for analysis - 0.020 (0.050) mg;

for the drug pure - 0.050 mg (0.100 mg).

The mass of sulfates indicated in brackets is established for standards in force before 01/01/95.

In case of disagreement in the assessment of the mass fraction of sulfates, the determination is carried out using the phototurbidimetric method; in this case, the mass of a sample of the chemically pure preparation is should be 30 g (25.5 cm).

(Changed edition, Amendment No. 1).

3.7. Determination of the mass fraction of free chlorine with -tolidine (carried out only in the absence of sulfites)

3.7.1. Equipment, reagents and solutions

Photoelectric colorimeter.

Hydrochloric acid according to this standard, not containing free chlorine (prepared by boiling for 5 minutes), concentrated and 3% solution.

-tolidine, 0.1% solution in 3% solution of hydrochloric acid, not containing chlorine.

A solution containing chlorine; prepared according to GOST 4212-76. By appropriate dilution, prepare a solution containing 0.01 mg of chlorine per 1 cm3.

3.7.2. Construction of a calibration graph

Prepare 5 reference solutions. To do this, solutions containing 0.01 in 50 cm, respectively, are placed in volumetric flasks with a capacity of 100 cm each; 0.02; 0.03; 0.04 and 0.05 mg Cl.

At the same time, prepare a control solution that does not contain free chlorine.

To each solution add 1 ml of α-tolidine solution, 10 ml of concentrated hydrochloric acid, adjust the volume of the solution to the mark with water and mix. After 5 minutes, the optical densities of the reference solutions are measured relative to the control solution in cuvettes with a light-absorbing layer thickness of 30 mm at a wavelength of 413 nm. Measurement of the optical density of reference solutions and analyzed solutions must be carried out within 20 minutes.

Based on the data obtained, a calibration graph is constructed.

3.7.3. Carrying out analysis

20 g (17 ml) of the drug is placed in a 100 ml volumetric flask containing 50 ml of water and 1 ml of -tolidine solution. The volume of the solution is adjusted to the mark with water and mixed. After 5 minutes, measure the optical density of the analyzed solution relative to the control solution in the same way as when constructing a calibration graph. The measurement should be carried out no more than 20 minutes. Based on the obtained optical density value, using the calibration graph, the content of free chlorine in the analyzed drug solution is determined.

The preparation is considered to comply with the requirements of this standard if the mass of free chlorine does not exceed:







If the mass fraction of iron in the preparation is less than 0.0001%, it is allowed to carry out the determination with potassium iodide and extraction with chloroform according to clause 3.8.

3.7.1-3.7.3. (Changed edition, Amendment No. 1).

3.8. Determination of the mass fraction of free chlorine by extraction method (carried out only in the absence of sulfites)

3.8.1. Reagents and solutions

Distilled water according to GOST 6709-72.

Iodine according to GOST 4159-79, 0.01 n. solution, freshly prepared.

Potassium iodide according to GOST 4232-74, chemical grade, 10% solution.

Sodium phosphate disubstituted 12-water according to GOST 4172-76, chemical grade, saturated solution.

Chloroform.

3.8.2. Carrying out analysis

70 g (60 cm) of the drug is placed in a separating funnel with a capacity of 200 cm, 20 cm of water, 2 cm of disubstituted sodium phosphate solution, 2 cm of potassium iodide solution are added, mixed and after 5 minutes, 5.5 cm of chloroform is added. The solution is shaken vigorously for 30 s. After separation, the chloroform layer of the analyzed solution is poured into a 10 cm test tube (with a ground-in stopper).

The drug is considered to comply with the requirements of this standard if the pink color of the chloroform layer of the analyzed solution is not more intense than the pink color of the chloroform layer of the solution prepared simultaneously with the analyzed solution and containing:

for the drug, chemically pure - 0.05 cm of iodine solution;

for the drug, pure for analysis - 0.05 cm of iodine solution;

for the preparation pure - 0.1 cm of iodine solution;

35 g (30 ml) of the drug, 10 ml of water, 1 ml of sodium phosphate solution, 1 ml of potassium iodide solution and 5 ml of chloroform.

1 cm is exactly 0.01 N., iodine solution corresponds to 0.00035 g Cl.

In case of disagreement in the assessment of the mass fraction of chlorine, the analysis is carried out with

Tolidin.

3.9. Determination of the mass fraction of ammonium salts

3.9.1. Reagents and solutions

Litmus paper.

Distilled water according to GOST 6709-72.

Sodium hydroxide, 20% solution without NH; prepared according to GOST 4517-87.

Nessler's reagent; prepared according to GOST 4517-87.

A solution containing NH; prepared according to GOST 4212-76.

3.9.2. Carrying out analysis

1.6 g (1.3 cm) of the drug containing 20 cm of water is placed in a conical flask with a capacity of 100 cm (with a mark at 50 cm), carefully neutralized using litmus paper with a solution of sodium hydroxide; bring the volume of the solution to the mark with water, mix and transfer the solution into a cylinder with a ground stopper. 2 cm of Nessler's reagent is added to the solution and mixed again.

The drug is considered to comply with the requirements of this standard if the observed color of the analyzed solution after 5 minutes is not more intense than the color of the reference solution prepared simultaneously with the analyzed solution and containing in the same volume:

for the drug chemically pure - 0.005 mg NH;

for the drug pure for analysis - 0.005 mg NH;

for the drug pure - 0.005 mg NH;

the amount of sodium hydroxide solution used to neutralize the analyzed solution, and 2 cm of Nessle’s reagent

3.10. The determination of the mass fraction of iron is carried out according to GOST 10555-75 using the 2.2"-dipyridyl or sulfosalicylic method.

(Changed edition, Amendment No. 1).

3.10.1. 2.2"-dipyridyl method

20 g (17 cm) of a chemically pure drug, 10 g (8.5 cm) of a pure drug for analysis and 2 g (1.7 cm) of a pure drug are placed in a platinum cup and evaporated to dryness in a water bath. The residue after evaporation is dissolved in 0.5 cm of hydrochloric acid, transferred to a volumetric flask with a capacity of 100 cm and the volume of the solution is adjusted to 40 cm with water. Next, the determination is carried out according to GOST 10555-75.



for the drug chemically pure - 0.01 mg;

for the drug pure for analysis - 0.01 mg;

for the drug pure - 0.006 (0.01) mg.

3.10.2. Sulfosalicylic method

10 g (8.5 cm) of the drug is placed in a conical flask with a capacity of 100 cm (with a 50 cm mark) and, while cooling, carefully neutralized dropwise with a 10% ammonia solution on litmus paper, then the determination is carried out according to GOST 10555-75.

The drug is considered to comply with the requirements of this standard if the mass of iron does not exceed:

for the drug chemically pure - 0.005 mg;

for the drug pure for analysis - 0.010 mg;

for the drug pure - 0.030 (0.050) mg.

The mass of iron indicated in brackets is established for the norm valid until 01/01/95.

At the same time, a control experiment is carried out under the same conditions and with the same amounts of reagents. If an iron impurity is detected, an amendment is made to the analysis result.

In case of disagreement in the assessment of the mass fraction of iron, the determination is carried out using the 2,2"-dipyridyl method.

3.10.1-3.10.2. (Introduced additionally, Amendment No. 1).

3.11. Determination of the mass fraction of arsenic is carried out according to GOST 10485-75 using the method using silver diethyldithiocarbamate or the method using bromine mercury paper.

(Changed edition, Amendment No. 1).

3.11.1. Silver diethyldithiocarbamate method

50 g (42.5 cm) of the drug is placed in a porcelain cup, 0.25 cm of concentrated nitric acid is added and evaporated in a water bath to a volume of 10 cm. After cooling, the residue is carefully transferred to a conical flask with a capacity of 100 cm, diluted with water and then determined using silver diethyldithiocarbamate.

The drug is considered to comply with the requirements of this standard if the mass of arsenic does not exceed:

for the drug chemically pure - 0.0025 mg;

for the drug pure for analysis - 0.0025 (0.0050) mg;

for the drug pure - 0.005 (0.010) mg.

3.11.2. Bromomercury paper method

20 g (17 cm) of the drug is placed in the flask of a device for determining arsenic, 6.5 cm of hydrochloric acid is added, the volume of the solution is adjusted to 150 cm with water, mixed and the determination is carried out using the arsine method in a volume of 150 cm (method 2), without adding a sulfuric solution acids.

The drug is considered to comply with the requirements of this standard if the color of brominated mercury paper from the analyzed solution is not more intense than the color of brominated mercury paper from the reference solution prepared simultaneously with the analyzed solution and containing 41.5 cm of solution;

for the drug chemically pure - 0.001 mg As;

for the drug pure for analysis - 0.001 (0.002) mg As;

for the drug pure - 0.002 (0.004) mg As,

6.5 cm of hydrochloric acid, 0.5 cm of stannous chloride solution and 5 g of zinc.

The mass of arsenic indicated in brackets is established for standards in force before 01/01/95.

In case of disagreement in the assessment of the mass fraction of arsenic, the determination is carried out using silver diethyldithiocarbamate

3.11.1-3.11.2. (Introduced additionally, Amendment No. 1).

3.12. Determination of the mass fraction of heavy metals

The determination is carried out according to GOST 17319-76. In this case, 10 g (8.5 cm) of the drug is placed in a porcelain cup and evaporated to dryness in a water bath. The dry residue is cooled, dissolved in 0.5 cm of hydrochloric acid solution, the contents of a 10 cm cup of water are washed off into a 50 cm flask, neutralized with a 25% ammonia solution to a slightly alkaline reaction, the volume of the solution is adjusted to 20 cm with water and the determination is carried out using the thioacetamide method. , photometrically or visually.

The drug is considered to comply with the requirements of this standard if the mass of heavy metals does not exceed:

for the drug chemically pure - 0.005 (0.01) mg;

for the drug pure for analysis - 0.01 mg;

for the drug pure - 0.02 mg.

The mass of heavy metals indicated in brackets is established for the norm valid until 01/01/95.

Determination using the hydrogen sulfide method is allowed.

In case of disagreement in the assessment of the mass fraction of heavy metals, the determination is carried out photometrically, using the thioacetamide method; in this case, the mass of a sample of the chemically pure preparation is and ch.d.a. should be 30 g (25.5 cm).

(Changed edition, Amendment No. 1).

4. PACKAGING, LABELING, TRANSPORTATION AND STORAGE

4.1. The drug is packaged and labeled in accordance with GOST 3885-73.

Type and type of container: 3-1, 3-2, 3-5, 3-8, 8-1, 8-2, 8-5, 9-1, 10-1.

Packing group: V, VI, VII.

The containers are marked with danger signs in accordance with GOST 19433-88 (class 8, subclass 8.1, drawing 8, classification code 8172) UN serial number 1789.

(Changed edition, Amendment No. 1).

4.2. The drug is transported by all modes of transport in accordance with the rules for the carriage of goods in force for this type of transport.

4.3. The drug is stored in the manufacturer's packaging in covered warehouses.

5. MANUFACTURER WARRANTY

5.1. The manufacturer guarantees that hydrochloric acid meets the requirements of this standard subject to storage and transportation conditions.

5.2. The guaranteed shelf life of the drug is one year from the date of manufacture.

Section 5. (Changed edition, Amendment No. 1).

Section 6. (Deleted, Amendment No. 1).



The text of the document is verified according to:
official publication
M.: IPK Standards Publishing House, 1997

Structural formula

True, empirical, or gross formula: HCl

Chemical composition of hydrochloric acid

Molecular weight: 36.461

Hydrochloric acid(also hydrochloric acid, hydrochloric acid, hydrogen chloride) - a solution of hydrogen chloride (HCl) in water, a strong monobasic acid. Colorless, transparent, caustic liquid, “smoking” in air (technical hydrochloric acid is yellowish in color due to impurities of iron, chlorine, etc.). It is present in a concentration of about 0.5% in the human stomach. The maximum concentration at 20 °C is 38% by weight, the density of such a solution is 1.19 g/cm³. Molar mass 36.46 g/mol. Salts of hydrochloric acid are called chlorides.

Physical properties

The physical properties of hydrochloric acid strongly depend on the concentration of dissolved hydrogen chloride. When solidified, it gives crystal hydrates of the compositions HCl H 2 O, HCl 2H 2 O, HCl 3H 2 O, HCl 6H 2 O.

Chemical properties

• Interaction with metals in the series of electrochemical potentials up to hydrogen, with the formation of salt and the release of hydrogen gas.
• Interaction with metal oxides to form soluble salt and water.
• Interaction with metal hydroxides to form soluble salt and water (neutralization reaction).
• Interaction with metal salts formed by weaker acids, such as carbonic acid.
• Interaction with strong oxidizing agents (potassium permanganate, manganese dioxide) with the release of chlorine gas.
• Reaction with ammonia to form thick white smoke consisting of tiny crystals of ammonium chloride.
• A qualitative reaction to hydrochloric acid and its salts is its interaction with silver nitrate, which forms a cheesy precipitate of silver chloride, insoluble in nitric acid.

Receipt

Hydrochloric acid is prepared by dissolving hydrogen chloride gas in water. Hydrogen chloride is produced by burning hydrogen in chlorine; the acid obtained in this way is called synthetic. Hydrochloric acid is also obtained from exhaust gases - by-product gases formed during various processes, for example, during the chlorination of hydrocarbons. The hydrogen chloride contained in these gases is called free gas, and the acid thus obtained is called free gas. In recent decades, the share of gas-free hydrochloric acid in production volume has gradually increased, displacing acid produced by burning hydrogen in chlorine. But hydrochloric acid obtained by burning hydrogen in chlorine contains fewer impurities and is used when high purity is required. In laboratory conditions, a method developed by alchemists is used, which consists of the action of concentrated sulfuric acid on table salt. At temperatures above 550 °C and excess table salt, interaction is possible. It is possible to obtain by hydrolysis of magnesium and aluminum chlorides (hydrated salt is heated). These reactions may not proceed to completion with the formation of basic chlorides (oxychlorides) of variable composition, for example. Hydrogen chloride is highly soluble in water. Thus, at 0 °C, 1 volume of water can absorb 507 volumes of HCl, which corresponds to an acid concentration of 45%. However, at room temperature the solubility of HCl is lower, so in practice 36% hydrochloric acid is usually used.

Application

Industry

• It is used in hydrometallurgy and electroplating (pickling, pickling), for cleaning the surface of metals during soldering and tinning, for producing chlorides of zinc, manganese, iron and other metals. In a mixture with surfactants, it is used to clean ceramic and metal products (inhibited acid is required here) from contamination and disinfection.
• It is registered in the food industry as an acidity regulator (food additive E507). Used to make seltzer (soda) water.

Medicine

• A natural constituent of human gastric juice. In a concentration of 0.3-0.5%, usually mixed with the enzyme pepsin, it is administered orally in case of insufficient acidity.

Features of treatment

Highly concentrated hydrochloric acid is a caustic substance that causes severe chemical burns if it comes into contact with the skin. Contact with eyes is especially dangerous. To neutralize burns, use a weak alkali solution, usually baking soda. When opening vessels with concentrated hydrochloric acid, hydrogen chloride vapors, attracting air moisture, form a fog that irritates the eyes and respiratory tract of humans. Reacting with strong oxidizing agents (bleach, manganese dioxide, potassium permanganate) forms toxic chlorine gas. In the Russian Federation, the circulation of hydrochloric acid with a concentration of 15% or more is limited.

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 is a homogeneous, colorless liquid with a pungent odor. It is a very caustic substance that reacts with most metals. Thanks to these properties, the material is widely used not only in industry, but also in everyday life.

The reagent is included in various means for getting rid of sewer blockages, but it can be used for this purpose independently, after diluting it with water in the required proportions.

The use of an acid solution in the home is not limited to this: the material is used to clean plumbing fixtures from rust and limescale, remove stubborn stains from fabrics, and even to remove scale from a kettle.

Precautionary measures

Since the reagent has a strong corrosive ability and releases toxic fumes when interacting with air, it is very important to use protective equipment when working with it.

When contacted with the skin and mucous membranes, the material causes chemical burns, and with prolonged exposure to an HCl atmosphere, tooth decay occurs, catarrh of the respiratory tract develops, and ulceration of the nasal mucosa occurs.

For protection purposes, it is necessary to use a gas mask, a rubberized apron, goggles and rubber gloves. Carry out work only in well-ventilated areas. If the reagent gets on your skin or mucous membranes, rinse the affected area with plenty of running water and seek medical help.

How to get rid of blockages?

For tough and targeted cleaning of sewers from organic deposits (fats, food debris, hair, detergents, etc.), dilute hydrochloric acid should be used. This method is not suitable for steel, iron and plastic pipes, since the connection can lead to corrosion and even the formation of through holes.

Before starting the procedure, you need to close the drain holes in other plumbing fixtures and ensure air flow into the room. This step is necessary, since during operation the acid will begin to actively produce toxic gases.

It is recommended to dilute the composition with water until a concentration of 3-10% is reached, then pour directly into the sewer and leave for 1-2 hours. Then you need to rinse the pipes with plenty of water and repeat the procedure if necessary.

Important point! The reagent should not be mixed with other drain cleaners, especially those based on alkalis. Otherwise, the reaction of these connections will cause severe damage to the pipes.

Other uses of acid in everyday life

An acid composition can easily clean faience plumbing from limescale and rust, remove urinary stone and other contaminants. For greater effect, an inhibitor (for example, methenamine) is added to the product, which slows down the chemical reaction.

The procedure is carried out as follows: the acid is diluted with water until a 5% concentration is reached and an inhibitor is added at the rate of 0.5 g per 1 liter of liquid. The resulting composition is treated with the surface and left for 30-40 minutes (depending on the degree of contamination), after which it is washed with water.

A weak acid solution is also used to remove berry stains, ink or rust from fabrics. To do this, the material is soaked in the composition for some time, after which it is thoroughly rinsed and washed as usual.

Descaling a kettle

For this purpose, use a 3-5% solution of hydrochloric acid, which is poured into a kettle and heated to 60-80 ° C for 1-2 hours or until scale deposits disintegrate. After this, the scale becomes loose and can be easily removed with a wooden spatula.

The effectiveness of the method is due to the fact that the reagent reacts with magnesium and calcium carbonates and converts them into soluble salts. The carbon dioxide released during this process destroys the scale layer and makes it loose. After removing salt deposits, wash the dishes thoroughly with clean water.

Important point! This method is not suitable for descaling enamel or aluminum kettles with chips and cracks: this will lead to corrosion of the metal and severe damage to it.

Conclusion

If precautions and safety rules are observed, hydrochloric acid will become an indispensable assistant in everyday life. And you can purchase it at the most affordable prices in our company.

HYDROCHLORIC ACID (hydrochloric acid) - a strong monobasic acid, a solution of hydrogen chloride HCl in water, is one of the most important components of gastric juice; in medicine it is used as a medicine for insufficiency of the secretory function of the stomach. S. to. is one of the most commonly used chemicals. reagents used in biochemical, sanitary and hygienic and clinical diagnostic laboratories. In dentistry, 10% S. solution is used to whiten teeth in case of fluorosis (see Teeth whitening). S. to. is used to produce alcohol, glucose, sugar, organic dyes, chlorides, gelatin and glue, in pharmaceuticals. industry, in tanning and dyeing leather, saponification of fats, in the production of activated carbon, dyeing fabrics, etching and soldering of metals, in hydrometallurgical processes for cleaning boreholes from deposits of carbonates, oxides and other sediments, in electroplating, etc.

S. to. for people who come into contact with it in the production process, represents a significant occupational hazard.

S. k. was known back in the 15th century. Its discovery is attributed to him. alchemist Valentin. For a long time it was believed that S. to. is an oxygen compound of a hypothetical chemical. element muria (hence one of its names - acidum muriaticum). Chem. the structure of the S. k. was finally established only in the first half of the 19th century. Davy (N. Davy) and J. Gay-Lussac.

In nature, free sodium chloride practically does not occur, but its salts sodium chloride (see Table salt), potassium chloride (see), magnesium chloride (see), calcium chloride (see), etc. are very widespread.

Hydrogen chloride HCl under normal conditions is a colorless gas with a specific pungent odor; when released into humid air, it “smoke” strongly, forming tiny droplets of aerosol S. to. Hydrogen chloride is toxic. Weight (mass) of 1 liter of gas at 0° and 760 mm Hg. Art. equal to 1.6391 g, air density 1.268. Liquid hydrogen chloride boils at -84.8° (760 mmHg) and solidifies at -114.2°. Hydrogen chloride dissolves well in water, releasing heat and forming hydrogen chloride; its solubility in water (g/100 g H20): 82.3 (0°), 72.1 (20°), 67.3 (30°), 63.3 (40°), 59.6 (50° ), 56.1 (60°).

S. to. is a colorless transparent liquid with a pungent odor of hydrogen chloride; impurities of iron, chlorine, or other substances color the soda yellowish-greenish.

The approximate value of S. concentration as a percentage can be found if the beat. reduce the weight of the S. by one and multiply the resulting number by 200; for example, if ud. S.'s weight is 1.1341, then its concentration is 26.8%, i.e. (1.1341 - 1) 200.

S. K. is chemically very active. It dissolves with the release of hydrogen all metals that have a negative normal potential (see Physical and chemical potentials), converts many metal oxides and hydroxides into chlorides and releases free compounds from salts such as phosphates, silicates, borates, etc.

In a mixture with nitrogen (3:1), the so-called. aqua regia, S. reacts with gold, platinum and other chemically inert metals, forming complex ions (AuCl4, PtCl6, etc.). Under the influence of oxidizing agents, S. is oxidized to chlorine (see).

S. to. reacts with many organic substances, for example, proteins, carbohydrates, etc. Certain aromatic amines, natural and synthetic alkaloids and other organic compounds of a basic nature form salts with S. to. hydrochlorides. Paper, cotton, linen, and many artificial fibers are destroyed under the influence of synthetic acid.

The main method of producing hydrogen chloride is synthesis from chlorine and hydrogen. The synthesis of hydrogen chloride proceeds in accordance with the reaction H2 + 2C1-^2HCl + 44.126 kcal. Other methods for producing hydrogen chloride are the chlorination of organic compounds, dehydrochlorination of organic chlorine derivatives and the hydrolysis of certain inorganic compounds with the elimination of hydrogen chloride. Less often, in the lab. In practice, they use the old method of producing hydrogen chloride by reacting table salt with sulfuric acid.

A characteristic reaction to S. and its salts is the formation of a white cheesy precipitate of silver chloride AgCl, soluble in an excess of aqueous ammonia solution:

HCl + AgN03 - AgCl + HN03; AgCl + 2NH4OH - [Ag (NHs)2] Cl + + 2H20.

Store S. to. in glass containers with ground-in stoppers in a cool room.

In 1897, I.P. Pavlov established that the parietal cells of the gastric glands of humans and other mammals secrete S. to a constant concentration. It is assumed that the mechanism of S.'s secretion consists of the transfer of H+ ions by a specific carrier to the outer surface of the apical membrane of the intracellular tubules of the parietal cells and their entry after additional conversion into gastric juice (see). C1~ ions from the blood penetrate into the parietal cell while simultaneously transporting the bicarbonate ion HCO in the opposite direction. Due to this, C1~ ions enter the parietal cell against the concentration gradient and from it into the gastric juice. Parietal cells secrete solution

S. to., the concentration of which is approx. 160 mmol!l.

Bibliography: Volfkovich S.I., Egorov A.P. and Epstein D.A. General chemical technology, vol. 1, p. 491 and others, M.-L., 1952; Harmful substances in industry, ed. N.V. Lazarev and I.D. Gadaskina, vol. 3, p. 41, L., 1977; Nekrasov B.V. Fundamentals of general chemistry, vol. 1 - 2, M., 1973; Emergency care for acute poisoning, Handbook of toxicology, ed. S. N. Golikova, p. 197, M., 1977; Fundamentals of Forensic Medicine, ed. N.V. Popova, p. 380, M.-L., 1938; Radbil O. S. Pharmacological basis for the treatment of diseases of the digestive system, p. 232, M., 1976; Rem and G. Course of inorganic chemistry, trans. with German, vol. 1, p. 844, M., 1963; Guide to forensic medical examination of poisonings, ed. R.V. Berezhny et al., p. 63, M., 1980.

N. G. Budkovskaya; N. V. Korobov (pharm.), A. F. Rubtsov (judgment).