hcl solution. Characteristics of hydrochloric acid

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 conducted by scientists and how did they add to the list of properties of hydrochloric acid, we will tell 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 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 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, incidentally obtained when working with organic compounds i.e. 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 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 drinking water, bleaching of fabrics, disinfection, production of plastic compounds and.

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 cheaper, purified - 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.

Purchased large enterprises. 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 oxidizers she behaves like a restorer.

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 NaCl). 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 digestion process, it is integral part 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 damage environment . Firstly, this leads to the release of vapors of the substance into 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 chemical properties soil and water.

Secondly, it can seep into groundwater, resulting in pollution. 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 is corrosive to 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

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 control acidity in the production citric acid, gelatin or fructose (E 507).

Do not forget that hydrochloric acid is dangerous for the skin. More great danger she presents 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 electroplating 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 the regeneration of Cl 2 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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Hydrochloric acid is a solution of hydrogen chloride in water. Hydrogen chloride (HCl) under normal conditions is a colorless gas with a specific pungent odor. However, we are dealing with its aqueous solutions, so we will focus only on them.

Hydrochloric acid is a colorless transparent solution with a pungent odor of hydrogen chloride. In the presence of impurities of iron, chlorine or other substances, the acid has a yellowish-green color. The density of a hydrochloric acid solution depends on the concentration of hydrogen chloride in it; some data is given in table 6.9.

Table 6.9. Density of hydrochloric acid solutions of various concentrations at 20°C.

From this table it can be seen that the dependence of the density of a hydrochloric acid solution on its concentration with an accuracy satisfactory for technical calculations can be described by the formula:

d = 1 + 0.5*(%) / 100

When dilute solutions boil, the HCl content in vapors is less than in solution, and when concentrated solutions boil, it is higher than in solution, which is reflected in the figure. rice. 6.12 equilibrium diagram. A constantly boiling mixture (azeotrope) at atmospheric pressure has a composition of 20.22% wt. HCl, boiling point 108.6°C.

Finally, another important advantage of hydrochloric acid is the almost complete independence of the time of its acquisition from the time of year. As seen from rice. No. 6.13, acid of industrial concentration (32-36%) freezes at temperatures that are practically unattainable for the European part of Russia (from -35 to -45 ° C), unlike sulfuric acid, which freezes at positive temperatures, which requires the introduction of a tank heating operation.

Hydrochloric acid does not have the disadvantages of sulfuric acid.

First, ferric chloride has an increased solubility in hydrochloric acid solution. (Fig. 6.14), which allows you to raise the concentration of ferric chloride in the solution to a value of 140 g/l and even more; the risk of sediment formation on the surface disappears.

Work with hydrochloric acid can be carried out at any temperature inside the building (even at 10°C), and this does not cause noticeable changes in the composition of the solution.

Rice. 6.12. Equilibrium diagram liquid - vapor for the system HCl - H 2 O.

Rice. 6.13. Diagram of the state (fusibility) of the HCl–H 2 O system.

Rice. 6.14. Equilibrium in the HCl - FeCl 2 system.

Finally, another very important advantage of hydrochloric acid is its full compatibility with flux, which uses chlorides.

Some disadvantage of hydrochloric acid as a reagent is its high volatility. The standards allow the concentration of 5 mg / m 3 of air volume in the workshop. The dependence of vapor pressure in the equilibrium state over acid of various percentage concentrations is given in table 6.10. In general, when the acid concentration in the bath is less than 15 wt %, this condition is satisfied. However, with an increase in temperatures in the workshop (that is, in the summer), this indicator may be exceeded. Certain information about what acid concentration at a particular shop temperature is acceptable can be determined from rice. 6.15.

The dependence of the etching rate on concentration and temperature is displayed in rice. 6.16.

Pickling deficiencies are usually caused by the following:

• using an acid with a greater or lesser concentration, compared to the optimal;
• short etching duration (the expected etching duration at different concentrations of acid and iron can be estimated from rice. 6.17;
• lower temperature compared to the optimum;
• lack of mixing;
• laminar motion of the pickling solution.

These problems are usually solved with the help of specific technological methods.

Table 6.10. Dependence of the equilibrium concentration of hydrogen chloride on the concentration of acid in the bath.

Acid concentration, %		Acid concentration, %	The concentration of HCl in the air, mg / m 3