The use of hydrochloric acid. How to prepare a solution of hydrochloric acid

Hydrochloric (Hydrochloric) acid - a very strong, dangerous chemical that has quite wide application in many areas of human life.

Brine is hydrogen chloride (HCL, an odorless thermal gas) combined with water (H2O). The boiling point depends on the concentration of the solution. The substance is flammable, storage conditions: only in dry rooms.

Used in medicine, dentistry, and for teeth whitening. If the stomach secretes insufficient amount of juice (enzyme), a hydrochloric acid solution is used as aid. In chemical laboratories, chlorine is a popular reagent for biochemistry experiments, sanitary standards and diagnostics.

Hydrochloric acid has become widely known in industry: dyeing fabrics, leather, soldering metal, removing scale, oxides, and is included in the manufacture of pharmaceuticals, as an oxidizing agent, etc.

Chemical Spectrum Properties

Acid interacts with many metals and salts. It is considered quite strong and is on a par with chamois. The main reaction manifests itself to all groups of metals located to the left of hydrogen (magnesium, iron, zinc - electrical potentials).

As a result of such exposure, salts are formed with the release of H into the air.

A diluted hydrochloric solution reacts with salts, but only with those formed by less strong acids. The well-known sodium and calcium carbonate, after interacting with it, disintegrate into water and carbon monoxide.

Nitric acid– qualitative response to saline solution. To obtain it, it is necessary to add silver nitrate to this reagent, as a result, a precipitate will form white, from which nitrogen substance is obtained

Using this mixture of water and hydrogen, many interesting experiments. For example, they dilute it with ammonia. As a result, you will get white smoke, thick, with the consistency of small crystals. Methylamine, aniline, manganese dioxide, potassium carbonate are reagents that are also susceptible to the influence of acid.

How is hydrochloric acid produced in the laboratory?

The production of the substance is large-scale, sale is free. In laboratory experiments, a solution is extracted by exposure to sulfuric acid. high concentration for regular kitchen salt (sodium chloride).

There are 2 methods for dissolving hydrogen chloride in water:

Hydrogen is burned in chlorine (synthetic).
Associated (absorbed). Its essence is to carry out organic chlorination, dehydrochlorination.

Chemical properties of hydrochloric acid quite high.

The substance is easily synthesized by pyrolysis of organochlorine waste. This happens as a result of the breakdown of hydrocarbons with a complete lack of oxygen. You can also use metal chlorides, which are raw materials for inorganic substances. If there is no concentrated sulfuric acid (electrolyte), take diluted one.

Potassium permanganate is another way to make a salt solution.

Regarding the extraction of the reagent in natural conditions, then most often this chemical mixture can be found in the waters of volcanic waste. Hydrogen chloride is a component of the minerals sylvite (potassium chloride, similar in appearance to game dice), bischofite. All these are methods of extracting the substance in industry.

In the human body, this enzyme is found in the stomach. A solution can be either an acid or a base. One of the common extraction methods is called sulfate.

How and why they are used

Perhaps this is rightfully one of the important substances that is found and necessary in almost all sectors of human life.

Localization of application:

Metallurgy. Cleaning surfaces from oxidized areas, dissolving rust, processing before soldering, tinning. Hydrochloric acid helps to extract small inclusions of metals from ores. Zirconium and titanium are obtained using a method of converting oxides into chlorides.
Food technology industry. A low concentration solution is used as a food additive. Gelatin and fructose for diabetics contain a pure emulsifier. Regular soda also has a high content of this substance. On the product packaging you will see it called E507.
Field of medicine. In case of insufficient acidity in the stomach and problems with the intestines. Low Ph levels lead to cancer. Even with proper nutrition and plenty of vitamins, the danger does not disappear; tests must be carried out to obtain juice from gastric tract, because in an insufficiently acidic environment, beneficial substances are practically not absorbed, and digestion is impaired.
The salt solution is used as an inhibitor - protection against dirt and infections, antiseptic effect. For the manufacture of adhesive mixtures, ceramic products. Heat exchangers are washed with it.
The procedure for purifying drinking water is also not complete without the participation of chlorine.
Production of rubber, bleaching of fabric bases.
You can care for your lenses using this solution.
Mouth rinse at home
The substance conducts electricity well.

Instructions for use

Hydrochloric acid can be used internally in medicine only as prescribed by a doctor. You cannot self-medicate.

The instructions are simple: The usual way to prepare a solution as a drug is to stir before use until it completely disappears in water. For half a 200 gram glass, 15 drops of medicine are prescribed. Take only during meals, 4 times a day.

Do not overdo it, this is not a panacea for diseases, consultation with a specialist is important. In case of overdose, ulcerative formations occur on the mucous membrane of the esophagus.

Side effects and contraindications

Refrain from taking if you are in a mood to allergic reactions, this may have a bad effect on general functions body.

Severe poisoning and burns

If the product comes into contact with the skin in concentrated form, you can get a severe toxicological burn. Penetration of excess steam into the respiratory tract (larynx, throat) contributes to causing poisoning.

A severe suffocating cough appears, the sputum may contain blood. Vision becomes cloudy, you want to constantly rub your eyes, the mucous membranes are irritated. The iris does not respond to bright light.

Getting burned by hydrochloric acid is not as scary as sulfuric acid, but the vapors that can enter the gastrointestinal tract can lead to serious consequences of alkali intoxication.

The first sign (symptom) is the presence of elevated body temperature. The characteristics of the action of this substance on the esophagus are visible in the following: wheezing in the lungs, vomiting, physical weakness, inability to take a deep breath, swelling of the respiratory tract.

When hit large quantity Inside, the toxicological picture is terrible: the volume of vomit increases, facial cyanosis and arrhythmia develop. Rib cage is compressed (asphyxia), followed by swelling of the larynx and death from painful shock.

For the listed symptoms, there is a certain classification of first aid actions.

It is very important to distinguish the stages of intoxication:

If a person is poisoned by vapors, it is necessary to urgently take him to fresh air. Wash your throat with sodium bicarbonate solution and apply a compress to your eyes. Go to the hospital immediately.
If the action of the acid is directed on the skin of a child or adult, it is important to properly treat the burned area. Rinse the skin for 15 minutes and apply burn ointment.
If damage is caused by the solution internal organs, urgent cleansing of the stomach by intubation and hospitalization is necessary.

Analogues of hydrochloric acid in preparations

Because the, permissible norm substances are used in medicine, they are contained in the following medications:

Magnesium Sulfate.
Calcium chloride.
Reamberin.

Remember that for human consumption, hydrogen chloride acid is used only in diluted form.

Structural formula

True, empirical, or gross formula: HCl

Chemical composition of hydrochloric acid

Molecular weight: 36.461

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

Physical properties

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

Chemical properties

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

Receipt

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

Application

Industry

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

Medicine

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

Features of treatment

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

Tank with hydrochloric acid

One of the strong monobasic acids and is formed when gas dissolves hydrogen chloride(HCl) in water is a clear, colorless liquid with a characteristic odor of chlorine. Dilute hydrochloric acid(as well as phosphorus) is often used to remove oxides when soldering metals.

Sometimes the gaseous compound HCl is mistakenly called hydrochloric acid. HCl is a gas that, when dissolved in water, forms hydrochloric acid.

Hydrogen chloride- a colorless gas with a sharp suffocating odor of chlorine. It turns into a liquid state at -84 0 C, and at -112 0 C it turns into a solid state.

Hydrogen chloride very soluble in water. So at 0 0 C, 500 liters of hydrogen chloride dissolve in 1 liter of water.
In a dry state, hydrogen chloride gas is quite inert, but can already interact with some organic substances, for example with acetylene (a gas that is released when carbide is lowered into water).

Chemical properties of hydrochloric acid

Chemical reaction with metals:
2HCl + Zn = ZnCl 2 + H 2 - salt is formed (in this case, a clear solution of zinc chloride) and hydrogen
- chemical reaction with metal oxides:
2HCl + CuO = CuCl 2 + H 2 O - salt is formed (in this case, a solution of green copper chloride salt) and water
- chemical reaction with bases and alkalis (or neutralization reaction)
HCl + NaOH = NaCl + H 2 O - neutralization reaction - salt is formed (in this case, a clear solution of sodium chloride) and water.
- chemical reaction with salts (for example, with chalk CaCO 3):
HCl + CaCO 3 = CaCl 2 + CO 2 + H 2 O - is formed carbon dioxide, water and a clear solution of calcium chloride CaCl 2.

Obtaining hydrochloric acid

Hydrochloric acid are obtained using a chemical reaction of the compound:

H 2 + Cl 2 = HCl - the reaction occurs at elevated temperatures

And also in the interaction of table salt and concentrated sulfuric acid:

H 2 SO 4 (conc.) + NaCl = NaHSO 4 + HCl

In this reaction, if the substance NaCl is in solid form, then HCl is a gas hydrogen chloride, which when dissolved in water forms hydrochloric acid

There are complex chemical substances that are similar in chemical structure to hydrochloric acid, but contain from one to four oxygen atoms in the molecule. These substances can be called oxygen-containing acids. With an increase in the number of oxygen atoms, the stability of the acid and its oxidizing ability increase.

TO oxygen-containing acids the following:

hypochlorous (HClO),
chloride (HClO 2),
chloric acid (HClO 3),
chlorine (HClO 4).

Each of these chemical complexes has all properties of acids and is capable of forming salts. Hypochlorous acid(HClO) forms hypochlorites, for example, the compound NaClO is sodium hypochlorite. Hypochlorous acid itself is formed when chlorine dissolves in cold water By chemical reaction:

H 2 O + Cl 2 = HCl + HClO,

As you can see, in this reaction two acids are formed at once - salt HCl and hypochlorous HClO. But the latter is an unstable chemical compound and gradually turns into hydrochloric acid;

Chloride HClO2 forms chlorites, salt NaClO 2 - sodium chlorite;
hypochlorous(HClO3) - chlorates, compound KClO 3, - potassium chlorate (or Berthollet's salt) - by the way, this substance is widely used in the manufacture of matches.

And finally, the strongest known monobasic acid - chlorine(HClO 4) - colorless, fuming in air, highly hygroscopic liquid - forms perchlorates, for example, KClO 4 - potassium perchlorate.

Salts formed hypochlorous HClO and chloride HClO 2 acids are unstable in the free state and are strong oxidizing agents in aqueous solutions. But the salts formed hypochlorous HClO 3 and chlorine HClO 4 acids based alkali metals(for example, also Berthollet salt KClO 3) are quite stable and do not exhibit oxidizing properties.

AlexBr 07-02-2010 09:30

There are two blades from our blacksmiths, shx 15 (bearing), I want to etch them with hydrochloric acid, I heard about the interesting results of this process.
They brought me acid, they said it was concentrated.
Now the question is how can I bring it up to 5-10% as needed for etching. Those. should I pour water there or into water and how much if the acid is 100 ml?
I understand the question is a loser, but I finished school and college a long time ago, and I don’t want to learn from my mistakes.

serber 07-02-2010 10:09

Only acid in water! In 1 liter of water 100 ml of HCl, we get a 10% solution

chief 07-02-2010 10:19

quote: Originally posted by serber:
Only acid in water! In 1 liter of water 100 ml of HCl, we get a 10% solution

We won’t get 10%!
Concentrated hydrochloric acid is not sulfuric acid; by definition it cannot be 100 percent, because hydrogen chloride is a gas.
Concentrated HCl - about 35-38 percent. Therefore, it is necessary to dilute approximately three times, and not ten times. If you need to be precise - by density:
http://ru.wikipedia.org/wiki/Hydrochloric acid

hunter1957 07-02-2010 10:29

The maximum achievable concentration of hydrochloric acid is 38-39%; then do the math yourself to get 5% acid. Regarding the etching of steel, there is such a thing that concentrated acids passivate the surface of the steel and the oxide film does not allow further etching.

pereira71 07-02-2010 11:41

Hello!
Now I’ll try to post a table with which you can calculate the percentage dilution of acids. Thanks to our Estonian colleagues.
Damn, it doesn't work...
If possible, then let me send it to someone for soap, and you can attach it. Excel file.

Nestor74 07-02-2010 12:55

pereira71
so put it somewhere on any file hosting service, and here it is, using cntrl-C cntrl-V, and that’s fine.

Kerogen 07-02-2010 13:32

quote: Originally posted by AleksBr:
Now the question is how can I bring it up to 5-10% as needed for etching. Those. should I pour water there or into water and how much if the acid is 100 ml?

Dilution calculator

pereira71 07-02-2010 13:54

While I was calving it was already done)))
Thanks Kerogen!

07-02-2010 16:28

Dilute 3-4 times, you will get what you need. What about

quote: Only acid in water!

I beg to differ, SALT can be stirred in any way you like. And SULFURIC acid is really only added to the water in a thin stream while stirring, and certainly in a container that will not crack due to strong heating of the mixture.
And to prepare solutions of other concentrations, I advise you to use the rule of the cross, look here for example

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 can be described with an accuracy satisfactory for technical calculations by the formula:

d = 1 + 0.5*(%) / 100

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

Finally one more thing important advantage hydrochloric acid is almost completely independent of the time of its acquisition from the time of year. As can be 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.

Firstly, ferric chloride has increased solubility in hydrochloric acid solution (Fig. 6.14), which allows you to increase the concentration of ferric chloride in the solution to 140 g/l and even more; the danger of sediment formation on the surface disappears.

Working 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. Liquid – vapor equilibrium diagram for the HCl – H 2 O system.

Rice. 6.13. State diagram (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 full compatibility with a flux that uses chlorides.

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

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

Etching defects are usually caused by the following:

using an acid with a higher or lower concentration compared to the optimal one;
short etching duration (the expected etching duration at different acid and iron concentrations can be estimated from rice. 6.17;
reduced temperature compared to optimal;
lack of mixing;
laminar movement of the etching solution.

These problems are usually solved using specific technological techniques.

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