Like acids. The education program requires students to memorize the names and formulas of six representatives of this group. And, looking through the table provided by the textbook, you notice in the list of acids the one that comes first and interested you in the first place - hydrochloric acid. Alas, neither properties nor any other information about it is studied in school classes. Therefore, those who are eager to gain knowledge outside school curriculum looking for additional information in all sorts of sources. But often many people do not find the information they need. And therefore, the topic of today’s article is devoted to this particular acid.

Definition

Hydrochloric acid is a strong monobasic acid. In some sources it may be called hydrochloric and hydrochloric acid, as well as hydrogen chloride.

It is a colorless, caustic liquid that fumes in air (photo on the right). However, industrial acid, due to the presence of iron, chlorine and other additives in it, has a yellowish color. Its highest concentration at a temperature of 20 o C is 38%. Density of hydrochloric acid with such parameters is equal to 1.19 g/cm 3 . But this compound has completely different data in different degrees of saturation. As the concentration decreases, there is a decrease numerical value molarity, viscosity and melting point, but increases specific heat and boiling point. Solidification of hydrochloric acid of any concentration gives various crystalline hydrates.

Chemical properties

All metals that come before hydrogen in the electrochemical series of their voltage can react with this compound, forming salts and releasing hydrogen gas. If they are replaced by metal oxides, the reaction products will be soluble salt and water. The same effect will occur when hydrochloric acid reacts with hydroxides. If you add any metal salt (for example, sodium carbonate), the remainder of which was taken from a weaker acid (carbonic acid), then the chloride of this metal (sodium), water and a gas corresponding to the acidic residue (in this case, carbon dioxide) are formed. .

Receipt

The compound now discussed is formed when hydrogen chloride gas, which can be produced by burning hydrogen in chlorine, is dissolved in water. Hydrochloric acid obtained using this method is called synthetic. Exhaust gases can also serve as a source for the extraction of this substance. And such hydrochloric acid will be called abgasic. IN Lately The level of production of hydrochloric acid using this method is much higher than its production by the synthetic method, although the latter produces the compound in a purer form. These are all the ways of its production in industry. However, in laboratories, hydrochloric acid is obtained in three ways (the first two differ only in temperature and reaction products) using various types interactions chemical substances, such as:

1. The effect of saturated sulfuric acid on sodium chloride at a temperature of 150 o C.
2. Interaction of the above substances under conditions with a temperature of 550 o C and above.
3. Hydrolysis of aluminum or magnesium chlorides.

Hydrometallurgy and electroplating cannot do without the use of hydrochloric acid, where it is needed to clean the surface of metals during tinning and soldering and to obtain chlorides of manganese, iron, zinc and other metals. In the food industry, this compound is known as food additive E507 - there it is an acidity regulator necessary to make seltzer (soda) water. Concentrated hydrochloric acid is also found in the gastric juice of any person and helps digest food. During this process, its degree of saturation decreases, because this composition is diluted with food. However, with prolonged fasting, the concentration of hydrochloric acid in the stomach gradually increases. And since this compound is very caustic, it can lead to stomach ulcers.

Conclusion

Hydrochloric acid can be both beneficial and harmful to humans. Contact with the skin results in severe chemical burns, and the vapors of this compound irritate the respiratory tract and eyes. But if you handle this substance carefully, it can come in handy more than once.

Hydrochloric acid

Chemical properties

Hydrochloric acid, hydrogen chloride or hydrochloric acid - solution HCl in water. According to Wikipedia, the substance belongs to the group of inorganic strong monobasic compounds. Full name of the compound in Latin: Hydrochloric acid.

Formula of Hydrochloric Acid in chemistry: HCl. In a molecule, hydrogen atoms combine with halogen atoms - Cl. If we consider the electronic configuration of these molecules, we can note that the compounds take part in the formation of molecular orbitals 1s-hydrogen orbitals and both 3s And 3p-atomic orbitals Cl. In the chemical formula of Hydrochloric Acid 1s-, 3s- And 3p-atomic orbitals overlap and form 1, 2, 3 orbitals. Wherein 3s-orbital is not bonding in nature. There is a shift in electron density towards the atom Cl and the polarity of the molecule decreases, but the binding energy of molecular orbitals increases (if we consider it along with other hydrogen halides ).

Physical properties of hydrogen chloride. It is a clear, colorless liquid that has the ability to smoke when exposed to air. Molar mass of chemical compound = 36.6 grams per mole. Under standard conditions, at an air temperature of 20 degrees Celsius, the maximum concentration of the substance is 38% by weight. The density of concentrated hydrochloric acid in this kind of solution is 1.19 g/cm³. In general, physical properties and characteristics such as density, molarity, viscosity, heat capacity, boiling point and pH, strongly depend on the concentration of the solution. These values ​​are discussed in more detail in the density table. For example, the density of Hydrochloric Acid is 10% = 1.048 kg per liter. When solidified, the substance forms crystal hydrates different compositions.

Chemical properties of Hydrochloric Acid. What does Hydrochloric Acid react with? The substance interacts with metals that are in the series of electrochemical potentials in front of hydrogen (iron, magnesium, zinc and others). In this case, salts are formed and gaseous gas is released. H. Lead, copper, gold, silver and other metals to the right of hydrogen do not react with Hydrochloric Acid. The substance reacts with metal oxides, forming water and soluble salt. Sodium hydroxide under the influence of sodium forms water. The neutralization reaction is characteristic of this compound.

Dilute Hydrochloric Acid reacts with metal salts, which are formed by weaker compounds. For example, propionic acid weaker than salt. The substance does not interact with more strong acids. And sodium carbonate will form after reaction with HCl chloride, carbon monoxide and water.

A chemical compound is characterized by reactions with strong oxidizing agents, with manganese dioxide , potassium permanganate : 2KMnO4 + 16HCl = 5Cl2 + 2MnCl2 + 2KCl + 8H2O. The substance reacts with ammonia , this produces thick white smoke, which consists of very small crystals of ammonium chloride. The mineral pyrolusite also reacts with Hydrochloric Acid, since it contains manganese dioxide : MnO2+4HCl=Cl2+MnO2+2H2O(oxidation reaction).

There is a qualitative reaction to hydrochloric acid and its salts. When a substance interacts with silver nitrate a white precipitate appears silver chloride and is formed nitrogen acid . Interaction reaction equation methylamine with hydrogen chloride looks like this: HCl + CH3NH2 = (CH3NH3)Cl.

The substance reacts with a weak base aniline . After aniline is dissolved in water, Hydrochloric Acid is added to the mixture. As a result, the base dissolves and forms aniline hydrochloride (phenylammonium chloride ): (C6H5NH3)Cl. The reaction of aluminum carbide with hydrochloric acid: Al4C3+12HCL=3CH4+4AlCl3. Reaction equation potassium carbonate with it looks like this: K2CO3 + 2HCl = 2KCl + H2O + CO2.

Obtaining hydrochloric acid

To obtain synthetic Hydrochloric Acid, hydrogen is burned in chlorine, and then the resulting hydrogen chloride gas is dissolved in water. It is also common to produce a reagent from exhaust gases, which are formed as by-products during the chlorination of hydrocarbons (exhaust Hydrochloric Acid). In the production of this chemical compound they use GOST 3118 77- for reagents and GOST 857 95– for technical synthetic hydrochloric acid.

In laboratory conditions, you can use an old method in which table salt is exposed to concentrated sulfuric acid. The product can also be obtained using a hydrolysis reaction aluminum chloride or magnesium . During the reaction may form oxychlorides variable composition. To determine the concentration of a substance, standard titers are used, which are produced in sealed ampoules, so that later it is possible to obtain a standard solution of known concentration and use it to determine the quality of another titrant.

The substance has a fairly wide range of applications:

• it is used in hydrometallurgy, pickling and pickling;
• when cleaning metals during tinning and soldering;
• as a reagent for obtaining manganese chloride , zinc, iron and other metals;
• in the preparation of mixtures with surfactants for cleaning metal and ceramic products from infection and dirt (inhibited hydrochloric acid is used);
• as an acidity regulator E507 in the food industry, as part of soda water;
• in medicine with insufficient acidity of gastric juice.

This chemical compound has a high hazard class - 2 (according to GOST 12L.005). When working with acid, special equipment is required. skin and eye protection. A fairly caustic substance that comes into contact with the skin or respiratory tract causes chemical burns. To neutralize it, alkali solutions are used, most often baking soda. Hydrogen chloride vapor forms a caustic mist with water molecules in the air, which irritates the respiratory tract and eyes. If the substance reacts with bleach, potassium permanganate and other oxidizing agents, a toxic gas is formed - chlorine. On the territory of the Russian Federation, the circulation of Hydrochloric Acid with a concentration of more than 15% is limited.

pharmachologic effect

Increases the acidity of gastric juice.

Pharmacodynamics and pharmacokinetics

What is gastric acidity? This is a characteristic of the concentration of Hydrochloric Acid in the stomach. Acidity is expressed in pH. Normally, gastric juice should produce acid and take an active part in the digestive process. Hydrochloric acid formula: HCl. It is produced by parietal cells located in the fundic glands, with the participation H+/K+ ATPases . These cells line the fundus and body of the stomach. The acidity of gastric juice itself is variable and depends on the number of parietal cells and the intensity of the processes of neutralization of the substance by the alkaline components of gastric juice. The concentration of the drug produced is stable and equal to 160 mmol/l. U healthy person Normally, no more than 7 and no less than 5 mmol of the substance should be produced per hour.

With insufficient or excessive production of Hydrochloric Acid, diseases of the digestive tract occur, and the ability to absorb certain microelements, such as iron, deteriorates. The product stimulates the secretion of gastric juice, reduces pH. Activates pepsinogen , converts it into an active enzyme pepsin . The substance has a beneficial effect on the acid reflex of the stomach and slows down the transition of incompletely digested food into the intestines. The fermentation processes of the contents of the digestive tract slow down, pain and belching disappear, and iron is better absorbed.

After oral administration, the drug is partially metabolized by saliva and gastric mucus, the contents of the duodenum. The unbound substance penetrates the duodenum, where it is completely neutralized by its alkaline contents.

Indications for use

The substance is part of synthetic detergents, concentrate for rinsing the mouth and caring for contact lenses. Dilute Hydrochloric Acid is prescribed for stomach diseases accompanied by low acidity, with hypochromic anemia in combination with iron supplements.

Contraindications

The medicine should not be used if allergies on a synthetic substance, for diseases of the digestive tract associated with high acidity, with.

Side effects

Concentrated Hydrochloric Acid can cause severe burns if it comes into contact with the skin, eyes or respiratory tract. As part of various lek. drugs use a diluted substance; with long-term use of large dosages, deterioration of the condition of tooth enamel may occur.

Instructions for use (Method and dosage)

Hydrochloric acid is used in accordance with the instructions.

The medicine is prescribed orally, having previously been dissolved in water. Usually use 10-15 drops of the drug per half glass of liquid. The medicine is taken with meals, 2-4 times a day. The maximum single dosage is 2 ml (about 40 drops). Daily dose – 6 ml (120 drops).

Overdose

Cases of overdose have not been described. With uncontrolled ingestion of the substance in large quantities, ulcers and erosions occur in the digestive tract. You should seek help from a doctor.

Interaction

The substance is often used in combination with pepsin and other medications. drugs. A chemical compound in the digestive tract interacts with bases and certain substances (see chemical properties).

special instructions

When treating with Hydrochloric Acid preparations, you must strictly adhere to the recommendations in the instructions.

Drugs containing (Analogs)

Level 4 ATX code matches:

For industrial purposes, inhibited hydrochloric acid (22-25%) is used. For medical purposes the solution is used: Hydrochloric acid diluted . The substance is also contained in a concentrate for rinsing the mouth. Parontal , in solution for the care of soft contact lenses Biotra .

1.2679; G crit 51.4°C, p crit 8.258 MPa, d crit 0.42 g/cm 3 ; -92.31 kJ/, DH pl 1.9924 kJ/ (-114.22°C), DH isp 16.1421 kJ/ (-8.05°C); 186.79 J/(mol K); (Pa): 133.32 10 -6 (-200.7 °C), 2.775 10 3 (-130.15 °C), 10.0 10 4 (-85.1 °C), 74, 0 10 4 (-40°C), 24.95 10 5 (O °C), 76.9 10 5 (50 °C); level of temperature dependence logp(kPa) = -905.53/T+ 1.75lgT- -500.77·10 -5 T+3.78229 (160-260 K); coefficient 0.00787; g 23 mN/cm (-155°C); r 0.29 10 7 Ohm m (-85°C), 0.59 10 7 (-114.22°C). See also table. 1.

R-value of HC1 at 25 °C and 0.1 MPa (mol %): in pentane - 0.47, hexane - 1.12, heptane - 1.47, octane - 1.63. The P-rhythm of HC1 in alkyl and aryl halides is low, for example. 0.07 / for C 4 H 9 C1. The pH value in the range from -20 to 60° C decreases in the series dichloroethane-tri-chloroethane-tetrachloroethane-trichlorethylene. The pH value at 10°C in a series is approximately 1/, in carbon ethers it is 0.6/, in carbonic compounds it is 0.2/. Stable R 2 O · HCl are formed. The P-rhythm of HC1 in obeys and is for KCl 2.51·10 -4 (800°С), 1.75·10 -4 / (900°С), for NaCl 1.90·10 -4 / (900° WITH).

Salt room. HCl in water is highly exothermic. process, for endless dilution. water solution D H 0 HCl -69.9 kJ/, Cl -- 167.080 kJ/; HC1 is completely ionized. The pH value of HC1 depends on the temperature (Table 2) and the partial HC1 in the gas mixture. Density of salt decomposition. and h at 20 °C are presented in table. 3 and 4. With increasing temperature, h hydrochloric acid decreases, for example: for 23.05% hydrochloric acid at 25 ° C h 1364 mPa s, at 35 ° C 1.170 mPa s hydrochloric acid containing h per 1 HC1, is [kJ/(kg K)]: 3.136 (n = 10), 3.580 (n = 20), 3.902 (n = 50), 4.036 (n = 100), 4.061 (n = 200).

HCl forms c (Table 5). In the HCl-water system there are three eutectics. points: - 74.7 °C (23.0% by weight HCl); -73.0°C (26.5% HCl); -87.5°C (24.8% HC1, metastable phase). Known HCl nH 2 O, where n = 8. 6 (mp. -40 ° C), 4. 3 (mp. -24.4 ° C), 2 (mp. -17.7 °C) and 1 (mp -15.35°C). crystallizes from 10% hydrochloric acid at -20, from 15% at -30, from 20% at -60 and from 24% at -80°C. The P-value of halides decreases with increasing HCl in hydrochloric acid, which is used for their.

Chemical properties. Pure dry HCl begins to dissociate above 1500°C and is chemically passive. Mn. , C, S, P do not interact. even with liquid HCl. C, reacts above 650 °C, with Si, Ge and B-c present. AlCl 3, with transition metals - at 300 °C and above. It is oxidized by O 2 and HNO 3 to Cl 2, with SO 3 it gives C1SO 3 H. About the solutions with org. connections see .

WITH Olina is chemically very active. Dissolves with the release of H 2 everything that has a negative. ,with me. and forms, releases free. who are you from people like , etc.

Receipt. In the HCl industry, the following is obtained. methods - sulfate, synthetic. and from exhaust gases (by-products) of a number of processes. The first two methods lose their meaning. Thus, in the USA in 1965 the share of waste hydrochloric acid was 77.6% of the total production volume, and in 1982 - 94%.

The production of hydrochloric acid (reactive, obtained by the sulfate method, synthetic, waste gas) is to obtain HCl from the last. his . Depending on the method of heat removal (reaches 72.8 kJ/), processes are divided into isothermal, adiabatic. and combined.

The sulfate method is based on interaction. NaCl with conc. H 2 SO 4 at 500-550 ° C. Reaction contain from 50-65% HCl (muffle) to 5% HCl (reactor with). It is proposed to replace H 2 SO 4 with a mixture of SO 2 and O 2 (process temperature approx. 540 °C, cat. Fe 2 O 3).

The direct synthesis of HCl is based on a chain reaction: H 2 + Cl 2 2HCl + 184.7 kJ K p is calculated by the equation: logK p = 9554/T- 0.5331g T+ 2.42.

The reaction is initiated by light, moisture, solid porous (, porous Pt) and certain minerals. in-you ( , ). Synthesis is carried out with an excess of H 2 (5-10%) in combustion chambers made of steel and refractory bricks. Naib. modern material that prevents HCl contamination - graphite, impregnated phenol-formal. resins. To prevent explosiveness, mix directly in the burner flame. To the top. the combustion chamber area is installed to cool the reaction. up to 150-160°C. Power modern graphite reaches 65 tons/day (in terms of 35% salt). In case of H2 deficiency, dil. is used. process modifications; for example, pass a mixture of Cl 2 and water through a layer of porous hot water:

2Cl 2 + 2H 2 O + C: 4HCl + CO 2 + 288.9 kJ

The temperature of the process (1000-1600 °C) depends on the type and presence of impurities in it, which are (for example, Fe 2 O 3). It is promising to use a mixture of CO with:

CO + H 2 O + Cl 2: 2HCl + CO 2

More than 90% of hydrochloric acid in developed countries is obtained from waste HCl, formed during dehydrochlorination of org. compounds, chlororg. waste, obtaining non-chlorinated potash. etc. Abgases contain various. quantity of HC1, inert impurities (N 2, H 2, CH 4), poorly soluble in org. substances (,), water-soluble substances (acetic acid), acidic impurities (Cl 2, HF, O 2) and. Application of isothermal advisable when the content of HC1 in exhaust gases is low (but when the content of inert impurities is less than 40%). Naib. Film ones are promising, making it possible to extract from 65 to 85% HCl from the initial exhaust gas.

Naib. Adiabatic schemes are widely used. . Abgases are introduced into the lower part, and (or diluted salt) - countercurrent to the upper one. The salt water is heated to temperature due to the heat of HCl. The change in temperature and HCl is shown in Fig. 1. The temperature is determined by the temperature corresponding to the temperature (max. boiling point of the azeotropic mixture - approx. 110°C).

In Fig. 2 shows a typical adiabatic circuit. HCl from exhaust gases formed during (eg, production). HCl is absorbed in 1, and the residues are poorly soluble in org. the substances are separated from the after in apparatus 2, further purified in the tail column 4 and separators 3, 5 and commercial salt is obtained.

Rice. 1. T-p distribution diagram (curve 1) and

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 State Committee 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 individual means protection, 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 are 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, filter it through a dense ashless filter, thoroughly washed 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.

Danger signs are applied to the container in accordance with GOST 19433-88 (class 8, subclass 8.1, drawing 8, classification code 8172) serial number UN 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

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 acid solution in the house is not limited to this: the material is used to clean plumbing fixtures from rust and limescale, removing stubborn stains from fabrics and even descaling 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.