The acid is called hcl. Preparation of hydrochloric acid solution
In water it is called hydrochloric acid ( HCl).
Physical properties of hydrochloric acid
Under normal conditions, hydrochloric acid is a clear, colorless liquid with a sharp, unpleasant odor.
Concentrated hydrochloric acid contains 37% hydrogen chloride. Such an acid "smokes" in air. Hydrogen chloride is released from it, which, with water vapor in the air, forms a "fog" consisting of small droplets of hydrochloric acid. Hydrochloric acid is slightly heavier than water (the specific gravity of 37% hydrochloric acid is 1.19).
School laboratories use mostly dilute hydrochloric acid.
Chemical properties of hydrochloric acid
Hydrochloric acid solution has a sour taste. Litmus in this solution is red, while phenolphthalein remains colorless.
Substances whose color changes from the action of alkalis and acids are called indicators.
Litmus, phenolphthalein - indicators for acids and alkalis. With the help of indicators, you can determine whether there is acid or alkali in the solution.
Hydrochloric acid reacts with many metals. The interaction of hydrochloric acid with sodium occurs especially rapidly. This can be easily seen from the experiment that can be carried out in the device.
Concentrated hydrochloric acid is poured into a test tube up to about 1/4 of its volume, fixed in a tripod and a small piece of sodium (the size of a pea) is lowered into it. Hydrogen is released from the test tube, which can be set on fire, and small crystals of common salt settle to the bottom of the test tube.
From this experience it follows that sodium displaces hydrogen from the acid and combines with the rest of its molecule:
2Na + 2HCl \u003d 2NaCl + H 2?
Under the action of hydrochloric acid on zinc, hydrogen is released, and the substance zinc chloride ZnCl 2 remains in the solution.
Since zinc is divalent, each zinc atom replaces two hydrogen atoms in two hydrochloric acid molecules:
Zn + 2HCl \u003d ZnCl 2 + H 2?
Hydrochloric acid also acts on iron, aluminum and many other metals.
As a result of these reactions, hydrogen is released, and metal chlorides remain in the solutions: ferric chloride FeCl 2, aluminum chloride AlCl 3, etc.
These metal chlorides are the products of substitution of hydrogen in hydrochloric acid by metals.
Compound substances that can be considered as products of substitution of hydrogen in an acid by a metal are called salts.
Metal chlorides are salts of hydrochloric acid.
Neutralization reaction (equation)
A very important chemical property of hydrochloric acid is its interaction with bases. Consider first its interaction with alkalis, for example with caustic soda.
To this end, pour a small amount of dilute sodium hydroxide solution into a glass cup and add a few drops of litmus solution to it.
The liquid will turn blue. Then we will pour in small portions into the same glass a solution of hydrochloric acid from a graduated tube (burette) until the color of the liquid in the glass changes to violet. Violet litmus indicates that the solution contains neither acid nor alkali.
Such a solution is called neutral. After boiling water out of it, table salt NaCl will remain. Based on this experience, it can be concluded that when solutions of caustic soda and hydrochloric acid are poured, water and sodium chloride are obtained. Water molecules were formed from the combination of hydrogen atoms (from acid molecules) with hydroxyl groups (from alkali molecules). Molecules of sodium chloride were formed from sodium atoms (from alkali molecules) and chlorine atoms - acid residues. The equation for this reaction can be written as follows:
Na |OH + H| Cl \u003d NaCl + H 2 O
Other alkalis also react with hydrochloric acid - caustic potash, caustic calcium.
Let's get acquainted with how hydrochloric acid reacts with insoluble bases, for example, with copper oxide hydrate. To this end, we will place a certain amount of this base in a glass and carefully add hydrochloric acid to it until the copper oxide hydrate is completely dissolved.
After evaporation of the blue solution thus obtained, crystals of copper chloride CuCl 2 are obtained. Based on this, the following equation can be written:
And in this case, a reaction occurred similar to the interaction of this acid with alkalis: hydrogen atoms from acid molecules combined with hydroxyl groups from base molecules, water molecules were formed. Copper atoms combined with chlorine atoms (residues from acid molecules) and formed salt molecules - copper chloride.
Hydrochloric acid reacts in the same way with other insoluble bases, for example, with iron oxide hydrate:
Fe(OH) 3 + 3HCl = 3H 2 O + FeCl 3
The reaction of an acid with a base to form a salt and water is called neutralization.
Hydrochloric acid is found in small amounts in the gastric juice of humans and animals and plays an important role in digestion.
Hydrochloric acid is used to neutralize alkalis, to obtain chloride salts. It also finds application in the production of some plastics, medicines.
The use of hydrochloric acid
Hydrochloric acid has a wide range of uses in the national economy, and you will often meet it when studying chemistry.
Large amounts of hydrochloric acid are used to pickle steel. Nickel-plated, zinc-plated, tin-plated (tin-plated), chrome-plated products are widely used in everyday life. To cover steel products and sheet iron with a layer of protective metal, the film of iron oxides must first be removed from the surface, otherwise the metal will not stick to it. Removal of oxides is achieved by etching the product with hydrochloric or sulfuric acid. The disadvantage of etching is that the acid reacts not only with the oxide, but also with the metal. To avoid this, a small amount of an inhibitor is added to the acid. Inhibitors are substances that slow down an unwanted reaction. Inhibited hydrochloric acid can be stored in steel containers and transported in steel tanks.
A solution of hydrochloric acid can also be bought at a pharmacy. Doctors prescribe a dilute solution of her patients with low acidity of gastric juice.
Hydrochloric acid is an inorganic substance, 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. Technical acid usually contains impurities that give it a slightly yellowish tint. Hydrochloric acid is often referred to as "fuming" because it releases hydrogen chloride vapor, which reacts with atmospheric moisture to form an acid mist.
It dissolves very well in water. At room temperature, the maximum possible mass content of hydrogen chloride is 38%. An acid concentration greater than 24% is considered concentrated.
Hydrochloric acid actively reacts with metals, oxides, hydroxides, forming salts - chlorides. HCl interacts 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, as a result of which a white cheesy precipitate precipitates.
Safety
The substance is very caustic, corrosive to skin, organic materials, metals and their oxides. In the air, it emits 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 the substances of the 2nd degree of danger (highly dangerous), the MPC of the reagent in the air is 0.005 mg/l. It is possible to work with hydrogen chloride only in filtering gas masks and protective clothing, including rubber gloves, an apron, safety shoes.
If acid is spilled, it is washed off with large amounts of water or neutralized with alkaline solutions. Victims of acid should be taken out of the danger zone, rinse the skin and eyes with water or soda solution, call a doctor.
It is allowed to transport and store a chemical reagent in a glass, plastic container, as well as in a metal container, covered from the inside with a rubber layer. The container must be hermetically sealed.
Receipt
Commercially, hydrochloric acid is produced from hydrogen chloride (HCl) gas. Hydrogen chloride itself is produced in two main ways:
- exothermic reaction of chlorine and hydrogen - in this way a high purity reagent is obtained, for example, for the food industry and pharmaceuticals;
- from accompanying industrial gases - an acid based on such HCl is called off-gas.
It's curious
It is to hydrochloric acid that nature "entrusted" the process of splitting 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!
The 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 updated daily to repair damaged areas. In addition to participating in the process of digestion of 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 its insufficiency; with anemia to improve the absorption of iron-containing drugs.
- In the food industry, this is a food additive, acidity regulator E507, as well as an ingredient in seltzer (soda) water. Used in the manufacture of fructose, gelatin, citric acid.
- In the chemical industry - the basis for the production of chlorine, soda, 
sodium glutamate, metal chlorides, for example zinc chloride, manganese chloride, iron chloride; synthesis of organochlorine substances; catalyst in organic synthesis.
- Most of the hydrochloric acid produced in the world is used in metallurgy to clean workpieces from oxides. For these purposes, an inhibited technical acid is used, which contains special inhibitors (retarders) of the reaction, due to which the reagent dissolves oxides, but not the metal itself. Metals are also poisoned with hydrochloric acid; clean them before tinning, soldering, galvanizing.
— Treat the skin before tanning.
- In the mining industry, it is in demand for cleaning boreholes from deposits, for processing ores and rock formations.
— In laboratory practice, hydrochloric acid is used as a popular reagent for analytical studies, for cleaning vessels from hard-to-remove contaminants.
– It is used in the rubber, pulp and paper industry, in ferrous metallurgy; for cleaning boilers, pipes, equipment from complex deposits, scale, rust; for cleaning ceramic and metal products.
Receipt. Hydrochloric acid is produced by dissolving hydrogen chloride in water.
Pay attention to the device shown in the figure on the left. It is used to produce hydrochloric acid. During the process of obtaining hydrochloric acid, monitor the gas outlet tube, it should be near the water level, and not be immersed in it. If this is not followed, then due to the high solubility of hydrogen chloride, water will enter the test tube with sulfuric acid and an explosion may occur.
In industry, hydrochloric acid is usually produced by burning hydrogen in chlorine and dissolving the reaction product in water.
physical properties. By dissolving hydrogen chloride in water, even a 40% hydrochloric acid solution with a density of 1.19 g/cm 3 can be obtained. However, commercially available concentrated hydrochloric acid contains about 0.37 mass fractions, or about 37% hydrogen chloride. The density of this solution is approximately 1.19 g/cm 3 . When an acid is diluted, the density of its solution decreases.
Concentrated hydrochloric acid is an invaluable solution, highly fuming in moist air, with a pungent odor due to the release of hydrogen chloride.
Chemical properties. Hydrochloric acid has a number of common properties that are characteristic of most acids. In addition, it has some specific properties.
Properties of HCL in common with other acids: 1) Color change of indicators 2) interaction with metals 2HCL + Zn → ZnCL 2 + H 2 3) Interaction with basic and amphoteric oxides: 2HCL + CaO → CaCl 2 + H 2 O; 2HCL + ZnO → ZnHCL 2 + H 2 O 4) Interaction with bases: 2HCL + Cu (OH) 2 → CuCl 2 + 2H 2 O 5) Interaction with salts: 2HCL + CaCO 3 → H 2 O + CO 2 + CaCL 2
Specific properties of HCL: 1) Interaction with silver nitrate (silver nitrate is a reagent for hydrochloric acid and its salts); a white precipitate will form, which does not dissolve in water or acids: HCL + AgNO3 → AgCL↓ + HNO 3 2O+3CL2
Application. A huge amount of hydrochloric acid is consumed to remove iron oxides before coating products from this metal with other metals (tin, chromium, nickel). In order for hydrochloric acid to react only with oxides, but not with metal, special substances are added to it, which are called inhibitors. Inhibitors- Substances that slow down reactions.
Hydrochloric acid is used to obtain various chlorides. It is used to produce chlorine. Very often, a solution of hydrochloric acid is prescribed to patients with low acidity of gastric juice. Hydrochloric acid is found in everyone in the body, it is part of the gastric juice, which is necessary for digestion.
In the food industry, hydrochloric acid is used only in the form of a solution. It is used to regulate acidity in the production of citric acid, gelatin or fructose (E 507).
Do not forget that hydrochloric acid is dangerous for the skin. It poses an even greater danger to the eyes. Influencing a person, it can cause tooth decay, irritation of mucous membranes, and suffocation.
In addition, hydrochloric acid is actively used in electroforming and hydrometallurgy (scale removal, rust removal, leather treatment, chemical reagents, as a rock solvent in oil production, in the production of rubbers, sodium glutamate, soda, Cl 2). Hydrochloric acid is used for Cl 2 regeneration, in organic synthesis (to obtain vinyl chloride, alkyl chlorides, etc.) It can be used as a catalyst in the production of diphenylolpropane, benzene alkylation.
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It is he who helps digest food. Normally, stomach acid is 0.3%.
This is enough to destroy a razor blade. It only takes about a week. The experiments, of course, were carried out outside the human body.
A dangerous object would damage the esophagus, would not stay in the stomach for 7 days.
What other experiments were carried out by scientists and how they added to the list of properties of hydrochloric acid, we will describe further.
Properties of hydrochloric acid
Hydrochloric acid formula It is a mixture of water and hydrogen chloride. Accordingly, the liquid is caustic, which allows it to destroy most substances.
The reagent is colorless. It gives off its scent. It is sour, suffocating. The aroma is sharp and, rather, is characterized as a stink.
If a hydrochloric acid solution technical, it contains impurities of the diatomic and. They give the liquid a yellowish tint.
Unlike, for example, mass of hydrochloric acid in solution cannot exceed 38%.
This is the critical point at which the substance simply evaporates. Both hydrogen chloride and water escape.
In this case, of course, the solution smokes. The maximum concentration is indicated for 20-degree air temperature. The higher the degrees, the faster the evaporation.
The density of 38% acid is just over 1 gram per cubic centimeter.
That is, even a concentrated substance is very watery. If you take a sip of this liquid, you will get burns.
But a weak 0.4% solution can be drunk. Naturally, in small quantities. Diluted acid has almost no smell, and it tastes tart and sour.
Hydrochloric acid interaction with other substances, largely justified by the monobasic composition of the reagent.
This means that only one hydrogen atom is included in the acid formula. This means that the reagent dissociates in water, that is, it dissolves completely.
The remaining substances, as a rule, dissolve already in the acid itself. So, in it all the metals that stand in front of hydrogen in the periodic system decay.
Dissolving in acid, they bind with chlorine. As a result, chlorides are obtained, that is,.
Reaction with hydrochloric acid will take place in most oxides and hydroxides of metals, as well as in them.
The main thing is that the latter are obtained from weaker acids. Salt is considered one of the strongest, put on a par with chamois.
From gases hydrochloric acid reacts violently with ammonia. This produces ammonium chloride. It crystallizes.
The particles are so small, and the reaction is so active, that the chloride rushes up. Outwardly it is smoke.
The reaction product with nitrate is also white. This interaction refers to the qualitatively determining hydrochloric.
The result of the reaction is a curdled precipitate. This is chloride. Unlike ammonium chloride, it rushes down, not up.
The reaction with nitrate is considered qualitative, since it is specific, not characteristic of other one-component acids.
They ignore the noble metals, of which the Argentum belongs. As you remember, it stands in the chemical series after hydrogen and, in theory, should not interact with hydrogen chloride dissolved in water.
Production of hydrochloric acid
hydrochloric acid is released not only in laboratory conditions, but also in nature. The human body is part of it.
But, hydrochloric acid in the stomach has already been discussed. However, this is not the only natural source, and, in the literal sense.
The reagent is found in some geysers and other water outlets of volcanic origin.
As for hydrogen chloride separately, it is part of bischofite, sylvin, halite. All of these are minerals.
Under the word "halite" is hidden ordinary salt, which is eaten, that is, sodium chloride.
Sylvin is chloride, its shape is reminiscent of dice. Bischofite - chloride, is present in abundance on the lands of the Volga region.
All of the listed minerals are suitable for industrial production of the reagent.
However, the most commonly used chloride sodium. Hydrochloric acid obtained when table salt is treated with concentrated sulfuric acid.
The essence of the method is reduced to the dissolution of gaseous hydrogen chloride in water. Two more approaches are based on this.
The first is synthetic. Hydrogen is burned in chlorine. The second is off-gas, that is, passing.
Hydrogen chloride is used, which is simultaneously obtained when working with organic compounds, that is, hydrocarbons.
Off-gas hydrogen chloride is formed during dehydrochlorination and chlorination of organic matter.
The substance is also synthesized during the pyrolysis of organochlorine waste. Chemists call pyrolysis the decomposition of hydrocarbons under conditions of oxygen deficiency.
Associated raw materials for hydrochloric acid can also be used when working with inorganic substances, for example, metal chlorides.
The same sylvin, for example, goes to the production of potash fertilizers. Plants also need magnesium.
Therefore, bischofite does not remain idle. As a result, they produce not only top dressing, but also hydrochloric acid.
The off-gas method displaces other methods for producing hydrochloric acid. The "side" industry accounts for 90% of the produced reagent. We will find out why it is made, where it is used.
The use of hydrochloric acid
Hydrochloric acid is used by metallurgists. The reagent is needed for decapitation of metals.
This is the name of the process of removing scale, rust, oxides and just dirt. Accordingly, private craftsmen also use acid, working, for example, with vintage items that have metal parts.
The reagent will dissolve their surface. There will be no trace of the problematic layer. But back to metallurgy.
In this industry, acid is beginning to be used to extract rare metals from ores.
The old methods are based on the use of their oxides. But, not all of them are easy to handle.
Therefore, the oxides began to be converted into chlorides, and then restored. Now, this is how they get, for example, and.
Since hydrochloric acid is contained in gastric juice, and a solution of low concentration can be drunk, it means that the reagent can also be used in the food industry.
Did you see the E507 additive on the product packaging? Know it's hydrochloric acid. It gives the very sourness and astringency to some cakes, sausages.
But, most often, a food emulsifier is added to fructose, gelatin and citric acid.
E507 is needed not only for taste, but also as an acidity regulator, that is, the Ph of the product.
Hydrochloric acid can be used in medicine. A weak solution of hydrochloric acid is prescribed for patients with low stomach acidity.
It is no less dangerous than elevated. In particular, the likelihood of stomach cancer increases.
The body does not receive useful elements, even if a person takes vitamins and eats properly.
The fact is that for adequate, full-fledged absorption of useful substances, standard acidity is needed.
The last use of the reagent is obvious. Chlorine is obtained from acid. It is enough to evaporate the solution.
Chlorine is used for purification of drinking water, bleaching of fabrics, disinfection, production of plastic compounds, etc.
It turns out, being active and aggressive, hydrochloric acid is necessary for mankind. There is a demand, there is a supply. Let's find out the price of the issue.
hydrochloric acid price
Price product depends on the type. Technical acid is cheaper, purified acid is more expensive. For a liter of the first they ask 20-40 rubles.
The cost depends on the concentration. For a liter of purified reagent they give about 20 rubles more.
The price tag also depends on the container, packaging, form of sale. Acquisition of acid in plastic canisters of 25-40 liters is more profitable.
In the medical field, in retail, the substance is offered in glass.
For 50 milliliters you will give 100-160 rubles. This is the most expensive hydrochloric acid.
Buy a solution of hydrogen chloride in a liter container is also not cheap. The packaging is designed for a private consumer, therefore, they ask for about 400-500 rubles per bottle.
Technical acid in retail is less common, it costs about 100 rubles cheaper. The main one is wholesale.
Buying big companies. It is for them that the prices indicated at the beginning of the chapter are relevant. The giants do not sell at retail.
Accordingly, the cost of a substance in small shops is a reflection of the “appetites” of shop owners.
By the way, about appetite. If the acidity in the stomach is increased, food is digested faster, you want to eat more often.
This leads to thinness, gastritis and ulcers. People with low acidity are prone to slagging, because food “roams” in the stomach for a long time, is poorly absorbed.
This is reflected on the skin, usually in the form of acne and dots. Is there such a problem?
Think not about expensive cosmetics, but about checking the gastrointestinal tract.
Hydrochloric acid (hydrochloric acid) - an aqueous solution of hydrogen chloride HCl, is a clear, colorless liquid with a pungent odor of hydrogen chloride. Technical acid has a yellowish-green color due to impurities of chlorine and iron salts. The maximum concentration of hydrochloric acid is about 36% HCl; such a solution has a density of 1.18 g/cm3. Concentrated acid "smokes" in air, since the escaping gaseous HCl forms tiny droplets of hydrochloric acid with water vapor.
Hydrochloric acid is not flammable, not explosive. It is one of the strongest acids, dissolves (with the release of hydrogen and the formation of salts - chlorides) all metals in the series of voltages up to hydrogen. Chlorides are also formed during the interaction of hydrochloric acid with metal oxides and hydroxides. With strong oxidizing agents, it behaves like a reducing agent.
Salts of hydrochloric acid - chlorides, with the exception of AgCl, Hg2Cl2, are highly soluble in water. Glass, ceramics, porcelain, graphite, fluoroplast are resistant to it.
Hydrochloric acid is obtained by dissolving hydrogen chloride in water, which is synthesized either directly from hydrogen and chlorine or obtained by the action of sulfuric acid on sodium chloride.
Produced technical hydrochloric acid has a strength of at least 31% HCl (synthetic) and 27.5% HCl (from NaCI). Commercial acid is called concentrated if it contains 24% or more HCl, if the HCl content is less, then the acid is called dilute.
Hydrochloric acid is used to obtain chlorides of various metals, organic intermediates and synthetic dyes, acetic acid, activated carbon, various adhesives, hydrolytic alcohol, and in electroforming. It is used for etching metals, for cleaning various vessels, casing pipes of boreholes from carbonates, oxides and other sediments and contaminants. In metallurgy, ores are treated with acid, in the leather industry - leather before tanning and dyeing. Hydrochloric acid is used in the textile, food industry, medicine, etc.
Hydrochloric acid plays an important role in the processes of digestion, it is an integral part of gastric juice. Diluted hydrochloric acid is prescribed orally mainly for diseases associated with insufficient acidity of gastric juice.
Hydrochloric acid is transported in glass bottles or gummed (coated with a layer of rubber) metal vessels, as well as in plastic containers.
Hydrochloric acid very dangerous for human health. Causes severe burns on contact with skin. Eye contact is especially dangerous.
If hydrochloric acid gets on the skin, it must be washed off immediately with a plentiful stream of water.
The mist and vapors of hydrogen chloride formed when concentrated acid interacts with air are very dangerous. They irritate mucous membranes and the respiratory tract. Prolonged work in an atmosphere of HCl causes catarrh of the respiratory tract, tooth decay, clouding of the cornea of the eyes, ulceration of the nasal mucosa, and gastrointestinal disorders.
Acute poisoning is accompanied by hoarseness, suffocation, runny nose, cough.
In the event of a leak or spill, hydrochloric acid can cause significant environmental damage. Firstly, this leads to the release of vapors of the substance into the atmospheric air in quantities exceeding sanitary and hygienic standards, which can lead to poisoning of all living things, as well as the appearance of acid precipitation, which can lead to a change in the chemical properties of soil and water.
Secondly, it can seep into groundwater, resulting in pollution of inland waters.
Where the water in rivers and lakes has become quite acidic (pH less than 5), fish disappear. When trophic chains are disturbed, the number of aquatic animal species, algae and bacteria is reduced.
In cities, acid precipitation accelerates the destruction of marble and concrete structures, monuments and sculptures. Hydrochloric acid corrodes metals when it comes in contact with metals, and reacts with substances such as bleach, manganese dioxide, or potassium permanganate to form toxic chlorine gas.
In the event of a spill, hydrochloric acid is washed off surfaces with plenty of water or an alkaline solution that neutralizes the acid.
The material was prepared on the basis of information from open sources