General characteristics of hydrochloric acid. Hydrochloric acid structural chemical formula

Structural formula

True, empirical, or gross formula: HCl

Chemical composition of hydrochloric acid

Molecular weight: 36.461

Hydrochloric acid(also hydrochloric, hydrochloric acid, hydrogen chloride) - a solution of hydrogen chloride (HCl) in water, a strong monobasic acid. Colorless, transparent, caustic liquid, "fuming" in air (technical hydrochloric acid is yellowish due to impurities of iron, chlorine, etc.). At a concentration of about 0.5%, it is present 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. salt of hydrochloric acid called chlorides.

Physical properties

The physical properties of hydrochloric acid are highly dependent on the concentration of dissolved hydrogen chloride. When solidified, it gives crystalline 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 standing in a series of electrochemical potentials up to hydrogen, with the formation of a salt and the release of gaseous hydrogen.
Interaction with metal oxides to form a soluble salt and water.
Interaction with metal hydroxides to form a soluble salt and water (neutralization reaction).
Interaction with metal salts formed by weaker acids, such as carbonic.
Interaction with strong oxidizing agents (potassium permanganate, manganese dioxide) with the release of gaseous chlorine.
Interaction with ammonia with the formation of thick white smoke, consisting of the smallest crystals of ammonium chloride.
A qualitative reaction to hydrochloric acid and its salts is its interaction with silver nitrate, which forms a curd precipitate of silver chloride, insoluble in nitric acid.

Receipt

Hydrochloric acid is produced by dissolving hydrogen chloride gas in water. Hydrogen chloride is obtained by burning hydrogen in chlorine, the acid obtained in this way is called synthetic. Hydrochloric acid is also obtained from off-gases - by-product gases generated during various processes, for example, during the chlorination of hydrocarbons. The hydrogen chloride contained in these gases is called off-gas, and the acid thus obtained is called off-gas. In recent decades, the share of waste hydrochloric acid in the production volume has been gradually increasing, displacing the acid obtained 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 in the action of concentrated sulfuric acid on table salt. At temperatures above 550 °C and an excess of table salt, interaction is possible. It is possible to obtain by hydrolysis of chlorides of magnesium, aluminum (hydrated salt is heated). These reactions may not go to completion with the formation of basic chlorides (oxychlorides) of variable composition, for example. Hydrogen chloride is highly soluble in water. So, at 0 °C, 1 volume of water can absorb 507 volumes of HCl, which corresponds to an acid concentration of 45%. However, when room temperature the solubility of HCl is lower, so 36% hydrochloric acid is usually used in practice.

Application

Industry

It is used in hydrometallurgy and electroforming (etching, pickling), for cleaning the surface of metals during soldering and tinning, for obtaining chlorides of zinc, manganese, iron, and other metals. Mixed with surfactants, it is used to clean ceramic and metal products(inhibited acid is needed here) from contamination and disinfection.
AT Food Industry registered as an acidity regulator (food additive E507). It is used to make seltzer (soda) water.

The medicine

Natural component human gastric juice. At a concentration of 0.3-0.5%, usually mixed with the enzyme pepsin, it is administered orally with insufficient acidity.

Features of circulation

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

Like acids. The education program provides for the memorization by students of 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, in the classroom at school, neither the property nor any other information about it is studied. Therefore, those who are eager to gain knowledge outside the school curriculum are looking for additional information in all sorts of sources. But often, many do not find the information they need. And so the topic of today's article is dedicated to this particular acid.

Definition

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

Physical properties

It is a colorless and fuming caustic liquid in the air (photo on the right). However, technical acid has a yellowish color due to the presence of iron, chlorine and other additives in it. Its largest concentration at a temperature of 20 ° C is 38%. The density of hydrochloric acid with such parameters is 1.19 g/cm 3 . But this compound in varying degrees of saturation has completely different data. With a decrease in concentration, the numerical value of molarity, viscosity and melting point decrease, but the specific heat capacity and boiling point increase. 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 interact with this compound, forming salts and releasing hydrogen gas. If they are replaced by metal oxides, then the reaction products will be soluble salt and water. The same effect will be in the interaction of hydrochloric acid with hydroxides. If, however, any salt of metals (for example, sodium carbonate) is added to it, the residue of which was taken from a weaker acid (carbonic), then chloride of this metal (sodium), water and gas corresponding to the acid residue (in this case, carbon dioxide) are formed. .

Receipt

The compound now discussed is formed when hydrogen chloride gas, which can be obtained by burning hydrogen in chlorine, is dissolved in water. Hydrochloric acid, which was obtained using this method, is called synthetic. Off-gases can also serve as a source for obtaining this substance. And such hydrochloric acid will be called off-gas. AT recent times the level of production of hydrochloric acid by this method is much higher than its production by the synthetic method, although the latter gives the compound in a purer form. These are all ways of getting it in industry. However, in laboratories, hydrochloric acid is obtained in three ways (the first two differ only in temperature and reaction products) using various kinds interactions chemical substances, such as:

Effect of saturated sulfuric acid on sodium chloride at 150°C.
The interaction of the above substances under conditions with a temperature of 550 ° C and above.
Hydrolysis of aluminum or magnesium chlorides.

Application

Hydrometallurgy and electroforming cannot do without the use of hydrochloric acid, where it is needed, in order 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 supplement E507 - there it is an acidity regulator, necessary in order to make seltzer (soda) water. Concentrated hydrochloric acid is also found in the gastric juice of any person and helps to 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. Its contact with the skin leads to the appearance of 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 in

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 to-t. The 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 electronic configuration of these molecules, it can be noted that the compounds take part in the formation of molecular orbitals 1s-hydrogen orbitals and both 3s and 3p-orbitals of an atom 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 binding. There is a shift of the electron density to 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 smokes when exposed to air. Molar mass of a chemical compound = 36.6 grams per mole. At 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. On the whole, 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 table of densities. For example, the density of Hydrochloric Acid 10% = 1.048 kg per liter. When solidified, the substance forms crystalline hydrates different compositions.

Chemical properties of hydrochloric acid. What does hydrochloric acid react with? The substance interacts with metals that stand in front of hydrogen in a series of electrochemical potentials (iron, magnesium, zinc, and others). In this case, salts are formed and gaseous 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 producing water and a soluble salt. Sodium hydroxide under the action of to-you forms and water. The neutralization reaction is characteristic of this compound.

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

For a chemical compound, reactions with strong oxidizing agents are characteristic, with manganese dioxide , potassium permanganate : 2KMnO4 + 16HCl = 5Cl2 + 2MnCl2 + 2KCl + 8H2O. The substance reacts with ammonia , which produces thick white smoke, which consists of very fine crystals of ammonium chloride. The mineral pyrolusite also reacts with hydrochloric acid, as 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 falls out white precipitate silver chloride and formed nitric acid . Interaction reaction equation methylamine with hydrogen chloride looks like this: HCl + CH3NH2 = (CH3NH3)Cl.

A substance reacts with a weak base aniline . After dissolving aniline in water, hydrochloric acid is added to the mixture. As a result, the base dissolves and forms aniline hydrochloride (phenylammonium chloride ): (С6Н5NH3)Cl. The reaction of interaction of aluminum carbide with hydrochloric acid: Al4C3+12HCL=3CH4+4AlCl3. Reaction equation potassium carbonate with which it looks like this: K2CO3 + 2HCl = 2KCl + H2O + CO2.

Getting hydrochloric acid

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

In the laboratory, you can use a long-standing method in which table salt is exposed to concentrated sulfuric acid. Also, the agent can be obtained using the hydrolysis reaction aluminum chloride or magnesium . During the reaction, oxychlorides variable composition. To determine the concentration of a substance, standard titers are used, which are available in sealed ampoules, so that later it is possible to obtain a standard solution of a known concentration and use it to determine the quality of another titrant.

The substance has a fairly wide scope:

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 manufacture 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 high class hazard - 2 (according to GOST 12L.005). When working with acid, special skin and eye protection. Sufficiently caustic substance in contact with the skin or inhalation causes chemical burns. To neutralize it, alkali solutions are used, most often - drinking soda. Hydrogen chloride vapor forms a corrosive 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, then a toxic gas, chlorine, is formed. 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 Active participation in the processes of digestion. Formula of hydrochloric acid: HCl. It is produced by parietal cells located in the fundic glands, with the participation of H+/K+-ATPase . 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. Concentration produced to - you are stable and equal to 160 mmol/l. At healthy person normally, no more than 7 and at least 5 mmol of the substance per hour should be produced.

With insufficient or excessive production of Hydrochloric Acid, diseases of the digestive tract occur, the ability to absorb certain microelements, such as iron, deteriorates. The drug 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, slows down the transition of incompletely digested food into the intestines. The processes of fermentation of the contents of the digestive tract slow down, pain and belching disappear, iron is better absorbed.

After oral administration, the drug is partially metabolized by saliva and gastric mucus, the contents of the duodenum 12. The unbound substance penetrates into the duodenum, where it is completely neutralized by its alkaline contents.

Indications for use

The substance is part of the synthetic detergents, rinse concentrate oral cavity contact lens care. Diluted Hydrochloric Acid is prescribed for diseases of the stomach, accompanied by low acidity, with hypochromic anemia in combination with iron preparations.

Contraindications

The medicine should not be used for allergies on a synthetic substance, in diseases of the digestive tract associated with hyperacidity, at .

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 prolonged use of large dosages, a deterioration in the condition of tooth enamel may occur.

Instructions for use (Method and dosage)

Hydrochloric acid is used in accordance with the instructions.

Inside the medicine is prescribed, previously dissolved in water. Usually use 10-15 drops of the drug in half a 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 are not described. With uncontrolled ingestion of a substance in large quantities ulcers and erosion occur in digestive tract. You should seek help from a doctor.

Interaction

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

special instructions

When treating with hydrochloric acid preparations, it is necessary to strictly adhere to the recommendations in the instructions.

Preparations containing (Analogues)

Coincidence in the ATX code of the 4th level:

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

Hydrochloric acid is a clear, colorless or yellowish liquid without suspended or emulsified particles.

Hydrochloric acid is a solution of gaseous hydrogen chloride HCl in water. The latter is a hygroscopic colorless gas with a pungent odor. The commonly used concentrated hydrochloric acid contains 36-38% hydrogen chloride and has a density of 1.19 g/cm3. Such an acid smokes in air, as gaseous HCl is released from it; when combined with air moisture, tiny droplets of hydrochloric acid are formed. It is a strong acid and reacts vigorously with most metals. However, metals such as gold, platinum, silver, tungsten and lead are practically not etched with hydrochloric acid. Many base metals dissolve in acid to form chlorides, such as zinc:

Zn + 2HCl \u003d ZnCl 2 + H 2

Pure acid is colorless, while technical acid has a yellowish tint caused by traces of compounds of iron, chlorine and other elements (FeCl3). Often a dilute acid containing 10% or less hydrogen chloride is used. Diluted solutions do not emit gaseous HCl and do not smoke in either dry or humid air.

The use of hydrochloric acid

Hydrochloric acid is widely used in industry for extracting metals from ores, pickling metals, etc. It is also used in the manufacture of soldering liquid, in the deposition of silver, and as an integral part of aqua regia.

The scale of the use of hydrochloric acid in industry is less than that of nitric acid. This is due to the fact that hydrochloric acid causes corrosion of steel equipment. In addition, its volatile vapors are quite harmful and also cause corrosion of metal products. This must be taken into account when storing hydrochloric acid. Hydrochloric acid is stored and transported in rubber-lined tanks and barrels, i.e. in the vessels inner surface which is covered with acid-resistant rubber, as well as in glass bottles and polyethylene utensils.

Hydrochloric acid is used to produce chlorides of zinc, manganese, iron and other metals, as well as ammonium chloride. Hydrochloric acid is used to clean the surfaces of metals, vessels, wells from carbonates, oxides and other sediments and contaminants. In this case, special additives are used - inhibitors that protect the metal from dissolution and corrosion, but do not delay the dissolution of oxides, carbonates and other similar compounds.

HCl is used in the industrial production of synthetic resins, rubbers. It is used as a raw material in the production of methyl chloride from methyl alcohol, ethyl chloride from ethylene, and vinyl chloride from acetylene.

Hydrochloric acid poisoning

HCl is poisonous. Poisoning usually occurs by mist formed when the gas interacts with water vapor in the air. HCl is also absorbed on the mucous membranes with the formation of acid, which causes severe irritation. At long work in an atmosphere of HCl, catarrhs of the respiratory tract, tooth decay, ulceration of the nasal mucosa, and gastrointestinal disorders are observed. Permissible content of HCl in the air of working premises is not more than 0.005 mg/l. For protection use a gas mask, goggles, rubber gloves, shoes, apron.

At the same time, our digestion is impossible without hydrochloric acid, its concentration in gastric juice is quite high. If the acidity in the body is lowered, then digestion is disturbed, and doctors prescribe such patients to take hydrochloric acid before eating.

The use of hydrochloric acid in everyday life

Concentrated "hodgepodge" is mixed with water in any proportion for domestic needs. A strong solution of this inorganic acid easily cleans faience plumbing from limescale and rust, and weaker ones can remove stains of rust, ink, berry juice from fabrics.

If you look closely, the toilet duck cleaner says that hydrochloric acid comes into the composition, so you need to work with it in rubber gloves and protect your eyes from splashing into them.

In addition, the life of no person is unthinkable without this acid - it is contained in the stomach and it is thanks to it that the food that has entered the stomach is dissolved (digested).

In addition, this acid serves as the first barrier against pathogenic bacteria that enter the stomach - they die in an acidic environment.

Well, people suffering from gastritis with high acidity, this acid is also well known. They even reduce its effect so that it does not destroy the walls of the stomach, with the help of special drugs that interact with it and reduce its concentration.

The most popular are preparations containing magnesium and aluminum oxides, for example, Maalox. However, there are extreme people who drink baking soda, although it has already been proven that this leads to only temporary relief.

Hydrochloric acid is a solution of gaseous hydrogen chloride HCl in water. The latter is a hygroscopic colorless gas with a pungent odor. Commonly consumed concentrated hydrochloric acid contains 36-38% hydrogen chloride and has a density 1.19 g/cm3. Such an acid smokes in air, since gaseous HCl; when combined with air moisture, tiny droplets of hydrochloric acid are formed.

Pure acid is colorless, while technical acid has a yellowish tint caused by traces of compounds of iron, chlorine and other elements ( FeCl 3 ).

Often a dilute acid containing 10% and less hydrogen chloride. Dilute solutions do not emit gaseous HCl and do not smoke in dry or humid air.

Hydrochloric acid is a volatile compound, as it evaporates when heated. It is a strong acid and reacts vigorously with most metals. However, metals such as gold, platinum, silver, tungsten and lead , hydrochloric acid is practically not etched. Many base metals, when dissolved in acid, form chlorides, for example zinc :

Zn + 2HCl \u003d ZnCl 2 + H 2.

Hydrochloric acid is widely used in industry for extracting metals from ores, pickling metals, etc. It is also used in the manufacture of soldering liquid, in the deposition silver and as part of royal vodka.

The scale of the use of hydrochloric acid in industry is less than nitric . This is due to the fact that hydrochloric acid causes corrosion of steel equipment. In addition, its volatile vapors are quite harmful and also cause corrosion of metal products. This must be taken into account when storing hydrochloric acid. Hydrochloric acid is stored and transported in rubber-lined tanks and barrels, i.e. in vessels, the inner surface of which is covered with acid-resistant rubber, as well as in glass bottles and polyethylene utensils.

Hydrochloric acid is used to produce chlorides zinc, manganese , iron and other metals, as well as ammonium chloride. Hydrochloric acid is used to clean the surfaces of metals, vessels, wells from carbonates, oxides and other sediments and contaminants. In this case, special additives are used - inhibitors that protect the metal from dissolution and corrosion, but do not delay the dissolution of oxides, carbonates and other similar compounds.

HCl used in the industrial production of synthetic resins, rubbers. It is used as a raw material in the production of methyl chloride from methyl alcohol, ethyl chloride from ethylene, and vinyl chloride from acetylene.

HCl poisonous. Poisoning usually occurs by mist formed when the gas interacts with water vapor in the air. HCl it is also absorbed on the mucous membranes with the formation of an acid that causes severe irritation. During prolonged work in the atmosphere HCl there are catarrhs of the respiratory tract, tooth decay, ulceration of the nasal mucosa, gastrointestinal disorders. Permissible content HCl in the air of working premises, no more 0 , 005 mg/l. For protection use a gas mask, goggles, rubber gloves, shoes, apron.