Hydrochloric acid (H Cl)hazard class 3

(concentrated hydrochloric acid)

Colorless, transparent, aggressive, non-flammable liquid with a pungent odor of hydrogen chloride. Represents 36% ( concentrated) a solution of hydrogen chloride in water. Heavier than water. It boils at a temperature of +108.6 0 C, and hardens at a temperature of –114.2 0 C. It dissolves well in water in all proportions, “smoke” in air due to the formation of hydrogen chloride with water vapor and fog droplets. Interacts with many metals, metal oxides and hydroxides, phosphates and silicates. When interacting with metals, it releases a flammable gas (hydrogen); when mixed with other acids, it causes spontaneous combustion of some materials. Destroys paper, wood, fabrics. Causes burns upon contact with skin. Exposure to fog hydrochloric acid, formed as a result of the interaction of hydrogen chloride with water vapor in the air, causes poisoning.

Hydrochloric acid is used in chemical synthesis, for processing ores, pickling metals. It is obtained by dissolving hydrogen chloride in water. Technical hydrochloric acid is produced with a strength of 27.5-38% by weight.

Hydrochloric acid is transported and stored in rubberized (coated with a layer of rubber) metal railway and automobile tanks, containers, cylinders, which are its temporary storage. Typically, hydrochloric acid is stored in above-ground cylindrical vertical rubberized tanks (volume 50-5000 m3) at atmospheric pressure and ambient temperature or in 20-liter glass bottles. Maximum storage volumes 370 tons.

Maximum permissible concentration (MPC) in the air inhabited items is 0.2 mg/m 3 in the air of the working area of ​​industrial premises 5 mg/m3. At a concentration of 15 mg/m3, the mucous membranes of the upper respiratory tract and eyes are affected, a sore throat, hoarseness, cough, runny nose, shortness of breath, and difficulty breathing appear. At concentrations of 50 mg/m3 and above, bubbling breathing occurs, sharp pains behind the sternum and in the stomach area, vomiting, spasm and swelling of the larynx, loss of consciousness. Concentrations of 50-75 mg/m 3 are difficult to tolerate. A concentration of 75-100 mg/m3 is intolerable. A concentration of 6400 mg/m 3 within 30 minutes is lethal. The maximum permissible concentration when using industrial and civil gas masks is 16,000 mg/m 3 .

When eliminating accidents, associated with a spill of hydrochloric acid, it is necessary to isolate the danger zone, remove people from it, stay to the windward side, and avoid low places. Directly at the accident site and in contamination zones with high concentrations at a distance of up to 50 m from the spill site, work is carried out in insulating gas masks IP-4M, IP-5 (using chemically bound oxygen) or breathing apparatus ASV-2, DASV (using compressed air ), KIP-8, KIP-9 (on compressed oxygen) and skin protection products (L-1, OZK, KIH-4, KIH-5). At a distance of more than 50 m from the source, where the concentration sharply decreases, skin protective equipment need not be used, and for respiratory protection, industrial gas masks with boxes of brands B, BKF, as well as civilian gas masks GP-5, GP-7, PDF-2D are used , PDF-2Sh complete with an additional cartridge DPG-3 or respirators RPG-67, RU-60M with a box of brand V.

Protective equipment		Time of protective action (hour) at concentrations (mg/m 3)
Name	Brand boxes				5000
Industrial gas masks large size
	BKF
Civilian gas masks GP-5, GP-7, PDF-2D, PDF-2Sh	with DPG-3
Respirators RU-60M, RPG-67

Due to the fact that hydrochloric acid "smoke" in the air with the formation droplets of fog interacting hydrogen chloride with water vapor, the presence in the air is determined hydrogen chloride.

The presence of hydrogen chloride is determined:

In the air of an industrial zone with an OKA-T-N gas analyzer Cl , gas alarm IGS-98-N Cl , universal gas analyzer UG-2 with a measurement range of 0-100 mg/m 3 , gas detector of industrial chemical emissions GPHV-2 in the range of 5-500 mg/m 3 .

In open space – with SIP “CORSAR-X” devices.

Indoors – SIP “VEGA-M”

Neutralizes hydrochloric acid and hydrogen chloride vapors the following alkaline solutions:

5% aqueous solution of caustic soda (for example, 50 kg of caustic soda per 950 liters of water);

5% aqueous solution of soda powder (for example, 50 kg of soda some powder for 950 liters of water);

5% aqueous solution of slaked lime (for example, 50 kg of slaked lime per 950 liters of water);

5% water solution of caustic soda (for example, 50 kg of caustic soda per 950 liters of water);

In the event of a hydrochloric acid spill and the absence of an embankment or pan, the spill site is fenced off with an earthen rampart, hydrogen chloride vapor is precipitated by placing a water curtain (water consumption is not standardized), the spilled acid is neutralized to safe concentrations with water (8 tons of water per 1 ton of acid) in compliance with all measures precautions or a 5% aqueous solution of alkali (3.5 tons of solution per 1 ton of acid) and neutralize 5% aqueous solution of alkali (7.4 tons of solution per 1 ton of acid).

To spray water or solutions, watering and fire trucks, auto-filling stations (ATs, PM-130, ARS-14, ARS-15), as well as hydrants and special systems available at chemically hazardous facilities are used.

To dispose of contaminated soil at the site of a hydrochloric acid spill, the surface layer of soil is cut off to the depth of contamination, collected and transported for disposal using earthmoving vehicles (bulldozers, scrapers, motor graders, dump trucks). The cut areas are covered with a fresh layer of soil and washed with water for control purposes.

Leader actions: isolate the danger zone within a radius of at least 50 meters, remove people from it, stay to the windward side, avoid low places. Enter the accident area only in full protective clothing.

Providing first aid:

In the contaminated area: rinse eyes and face generously with water, put on anti-vogaza, urgent withdrawal (removal) from the outbreak.

After evacuating a contaminated area: warming, rest, washing off the acid from exposed skin and clothing with water, washing the eyes abundantly with water, if breathing is difficult, apply heat to the neck area, subcutaneously - 1 ml. 0.1% atropine sulfate solution. Immediate evacuation to a medical facility.

What is a hydrochloric acid solution? It is a compound of water (H2O) and hydrogen chloride (HCl), which is a colorless thermal gas with a characteristic odor. Chlorides dissolve well and break down into ions. Hydrochloric acid is the most famous compound that forms HCl, so we can talk about it and its features in detail.

Description

A solution of hydrochloric acid belongs to the class of strong. It is colorless, transparent and caustic. Although technical hydrochloric acid has a yellowish color due to the presence of impurities and other elements. The air “smoke”.

It is worth noting that this substance is present in the body of every person. In the stomach, to be more precise, in a concentration of 0.5%. Interestingly, this amount is enough to completely destroy a razor blade. The substance will corrode it in just a week.

Unlike sulfuric acid, by the way, the mass of hydrochloric acid in solution does not exceed 38%. We can say that this indicator is a “critical” point. If you start to increase the concentration, the substance will simply evaporate, as a result of which hydrogen chloride will simply evaporate along with the water. Plus, this concentration is maintained only at 20 °C. The higher the temperature, the faster evaporation occurs.

Interaction with metals

A solution of hydrochloric acid can undergo many reactions. First of all, with metals that come before hydrogen in the series of electrochemical potentials. This is the sequence in which the elements proceed as their inherent measure, the electrochemical potential (φ 0), increases. This indicator is extremely important in half-reactions of cation reduction. In addition, it is this series that demonstrates the activity of metals in redox reactions.

So, interaction with them occurs with the release of hydrogen in the form of gas and the formation of salt. Here is an example of a reaction with sodium, a soft alkali metal: 2Na + 2HCl → 2NaCl +H 2.

With other substances, interactions proceed according to similar formulas. This is what the reaction with aluminum, a light metal, looks like: 2Al + 6HCl → 2AlCl 3 + 3H 2.

Reactions with oxides

Hydrochloric acid solution also interacts well with these substances. Oxides are binary compounds of an element with oxygen that have an oxidation state of -2. Everyone famous examples are sand, water, rust, dyes, carbon dioxide.

Hydrochloric acid does not interact with all compounds, but only with metal oxides. The reaction also produces soluble salt and water. An example is the process that occurs between an acid and magnesium oxide, an alkaline earth metal: MgO + 2HCl → MgCl 2 + H 2 O.

Reactions with hydroxides

This is the name for inorganic compounds that contain a hydroxyl group -OH, in which hydrogen and oxygen atoms are connected covalent bond. And, since a solution of hydrochloric acid reacts only with metal hydroxides, it is worth mentioning that some of them are called alkalis.

So the resulting reaction is called neutralization. Its result is the formation of a weakly dissociating substance (i.e. water) and salt.

An example is the reaction of a small volume of solution of hydrochloric acid and barium hydroxide, a soft alkaline earth malleable metal: Ba(OH) 2 + 2HCl = BaCl 2 + 2H 2 O.

Interaction with other substances

In addition to the above, hydrochloric acid can react with other types of compounds. In particular with:

• Metal salts that are formed by other, weaker acids. Here is an example of one of these reactions: Na 2 Co 3 + 2HCl → 2NaCl + H 2 O + CO 2. Shown here is the interaction with a salt formed by carbonic acid (H 2 CO 3).
• Strong oxidizing agents. With manganese dioxide, for example. Or with potassium permanganate. Such reactions are accompanied by the release of chlorine. Here is one example: 2KMnO 4 +16HCl → 5Cl 2 + 2MnCl 2 + 2KCl + 8H 2 O.
• Ammonia. This is hydrogen nitride with the formula NH 3, which is a colorless but pungent-smelling gas. The consequence of its reaction with a solution of hydrochloric acid is a mass of thick white smoke consisting of small crystals of ammonium chloride. Which, by the way, is known to everyone as ammonia (NH 4 Cl). The interaction formula is as follows: NH 3 + HCl → NH 4 CL.
• Silver nitrate is an inorganic compound (AgNO 3), which is a salt of nitric acid and silver metal. As a result of the contact of a hydrochloric acid solution with it, a qualitative reaction occurs - the formation of a cheesy precipitate of silver chloride. Which does not dissolve in nitrogen. It looks like this: HCL + AgNO 3 → AgCl↓ + HNO 3 .

Obtaining the substance

Now we can talk about what is done to form hydrochloric acid.

First, by burning hydrogen in chlorine, we obtain main component- hydrogen chloride gas. Which is then dissolved in water. The result of this simple reaction is the formation of a synthetic acid.

This substance can also be obtained from exhaust gases. These are chemical waste (by-product) gases. They are formed through a variety of processes. For example, during the chlorination of hydrocarbons. The hydrogen chloride contained in them is called off-gas. And the acid obtained in this way, respectively.

It should be noted that in recent years the share of waste substances in the total volume of its production increases. And the acid formed due to the combustion of hydrogen in chlorine is displaced. However, to be fair, it should be noted that it contains fewer impurities.

Use in everyday life

Many cleaning products that householders use regularly contain a certain proportion of hydrochloric acid solution. 2-3 percent, and sometimes less, but it is there. That is why, when putting the plumbing in order (washing tiles, for example), you need to wear gloves. Highly acidic products can harm the skin.

The solution is also used as a stain remover. It helps remove ink or rust from clothes. But for the effect to be noticeable, you need to use a more concentrated substance. A 10% hydrochloric acid solution is suitable. By the way, it removes scale perfectly.

It is important to store the substance correctly. Keep the acid in glass containers and in places where animals and children cannot reach. Even a weak solution that gets on the skin or mucous membrane can cause a chemical burn. If this happens, it is necessary to immediately rinse the areas with water.

In the field of construction

The use of hydrochloric acid and its solutions is a popular way to improve many construction processes. For example, it is often added to a concrete mixture to increase frost resistance. In addition, this way it hardens faster, and the resistance of the masonry to moisture increases.

Hydrochloric acid is also used as a limestone remover. Its 10% solution is best way fighting dirt and marks on red brick. It is not recommended to use it to clean others. The structure of other bricks is more sensitive to the effects of this substance.

In medicine

In this area under consideration, the substance is also actively used. Dilute hydrochloric acid has the following effects:

• Digests proteins in the stomach.
• Stops the development of malignant tumors.
• Helps in the treatment of cancer.
• Normalizes acid-base balance.
• Serves as an effective remedy for the prevention of hepatitis, diabetes mellitus, psoriasis, eczema, rheumatoid arthritis, cholelithiasis, rosacea, asthma, urticaria and many other ailments.

Did you come up with the idea of ​​diluting the acid and using it internally in this form, and not as part of medications? This is practiced, but it is strictly forbidden to do this without medical advice and instructions. By incorrectly calculating the proportions, you can swallow an excess of hydrochloric acid solution and simply burn your stomach.

By the way, you can still take medications that stimulate the production of this substance. And not only chemical ones. The same calamus peppermint and wormwood contribute to this. You can make decoctions based on them yourself and drink them for prevention.

Burns and poisoning

No matter how effective this remedy is, it is dangerous. Hydrochloric acid, depending on the concentration, can cause four degrees of chemical burns:

1. There is only redness and pain.
2. Blisters with clear liquid and swelling appear.
3. Necrosis forms upper layers skin. The blisters fill with blood or cloudy contents.
4. The lesion reaches the tendons and muscles.

If the substance somehow gets into your eyes, you need to rinse them with water and then with a soda solution. But in any case, the first thing you need to do is call an ambulance.

Getting acid inside can cause sharp pains in the chest and abdomen, swelling of the larynx, vomiting bloody masses. As a result - severe pathologies of the liver and kidneys.

And the first signs of vapor poisoning include a dry, frequent cough, choking, damage to teeth, burning in the mucous membranes and abdominal pain. The first emergency aid is washing and rinsing the mouth with water, as well as access to fresh air. Only a toxicologist can provide real help.

It is what helps digest food. Normally, acid in the stomach 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 and would not stay in the stomach for 7 days.

We will tell you further what other experiments the scientists performed and how they added to the list of properties of hydrochloric acid.

Properties of hydrochloric acid

Hydrochloric acid formula is a mixture of water and hydrogen chloride. Accordingly, the liquid is caustic, which allows it to destroy most substances.

The reagent is colorless in appearance. Its smell gives it away. It is sour, suffocating. The aroma is pungent and, rather, is characterized as a stench.

If hydrochloric acid solution technical, it contains impurities of diatomic and. They give the liquid a yellowish tint.

Unlike, for example, mass of hydrochloric acid in solution cannot exceed 38%.

This critical point, in which the substance simply evaporates. Both hydrogen chloride and water evaporate.

Naturally, the solution smokes. The maximum concentration is indicated for 20-degree air temperature. The higher the degrees, the faster the evaporation occurs.

The density of 38 percent acid is slightly more than 1 gram per cubic centimeter.

That is, even a concentrated substance is very watery. If you drink this liquid, you will get burns.

But you can drink a weak 0.4 percent solution. Naturally, in small quantities. Dilute acid has almost no smell, and its taste is tart and sour.

Reaction of hydrochloric acid with other substances, is largely justified by the monobasic composition of the reagent.

This means that the acid formula contains only one hydrogen atom. This means that the reagent dissociates in water, that is, it dissolves completely.

The remaining substances, as a rule, dissolve in the acid itself. Thus, all metals that stand in front of hydrogen in the periodic table disintegrate in it.

When dissolved in acid, they bind with chlorine. As a result, chlorides are obtained, that is, .

Reaction with hydrochloric acid occurs in most metal oxides and hydroxides, as well as in their .

The main thing is that the latter be obtained from weaker acids. Solyannaya is considered one of the strongest, ranked on a par with chamois.

From gases hydrochloric acid Reacts violently with ammonia. In this case, ammonium chloride is formed. It crystallizes.

The particles are so small and the reaction is so active that the chloride rushes upward. Outwardly it is smoke.

The reaction product with nitrate is also white. This interaction is one of the qualitatively determining salt interactions.

The result of the reaction is a cheesy sediment. This is chloride. Unlike ammonium chloride, it rushes down, not up.

The reaction with nitrate is considered qualitative because it is specific, not characteristic of other single-component acids.

They ignore noble metals, which include argentum. As you remember, it is in the chemical series after hydrogen and, in theory, should not interact with hydrogen chloride dissolved in water.

Hydrochloric acid production

Hydrochloric acid is released not only in laboratory conditions, but also in nature. Human body- part of it.

But, hydrochloric acid in the stomach has already been discussed. However, this is not the only one natural spring, 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, sylvite, and halite. All these are minerals.

The word “halite” means ordinary salt that is used in food, that is, sodium chloride.

Silvin is a chloride, its shape resembles dice. Bishofite is a chloride, present in abundance in the Volga region.

All of the listed minerals are suitable for industrial production of the reagent.

But, most often they use chloride sodium Hydrochloric acid is obtained when table salt is exposed to concentrated sulfuric acid.

The essence of the method is to dissolve hydrogen chloride gas in water. Two other approaches are based on this.

The first one is synthetic. Hydrogen is burned in chlorine. The second is off-gas, that is, associated.

Hydrogen chloride is used, which is incidentally obtained when working with organic compounds, that is, hydrocarbons.

Absent 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.

Hydrochloric acid can also be used as a by-product when working with inorganic substances, for example, metal chlorides.

The same sylvite, for example, is used to produce potassium fertilizers. Plants also need magnesium.

Therefore, bischofite does not remain idle. As a result, they produce not only fertilizing, but also hydrochloric acid.

The gas-absorbing method displaces other methods of producing hydrochloric acid. The “by-product” industry accounts for 90% of the reagent produced. Let's find out why it is made and where it is used.

Application of hydrochloric acid

Hydrochloric acid is used by metallurgists. The reagent is needed for pickling metals.

This is the name for the process of removing scale, rust, oxides and just dirt. Accordingly, private craftsmen also use acid when working, for example, with vintage items that contain metal parts.

The reagent will dissolve their surface. There will be no trace left of the problem layer. But, let's return to metallurgy.

In this industry, acid is beginning to be used to extract rare metals from ores.

Old methods are based on the use of their oxides. But, not all of them are easy to process.

Therefore, the oxides began to be converted into chlorides, and then reduced. Now, this is how they get, for example, and.

Since hydrochloric acid is contained in gastric juice, and a low concentration solution can be drunk, this means that the reagent can also be used in food industry.

Did you see the E507 additive on the product packaging? Know that this is hydrochloric acid. It gives that very sourness and tartness to some cakes and sausages.

But most often food emulsifiers are 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 to patients with low stomach acidity.

It is no less dangerous than increased. In particular, the likelihood of stomach cancer increases.

The body does not receive enough useful elements, even if a person takes vitamins and eats right.

The fact is that for adequate, complete absorption of nutrients, 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, fabric bleaching, disinfection, production of plastic compounds, etc.

It turns out that hydrochloric acid, being active and aggressive, is necessary for humanity. There is demand, there is 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 for 20-40 rubles.

Cost depends on concentration. For a liter of purified reagent they cost about 20 rubles more.

The price tag also depends on the container, packaging, and form of sale. Purchasing 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 pay 100-160 rubles. This is the most expensive hydrochloric acid.

Buy Hydrogen chloride solution in a liter container is also not cheap. The packaging is designed for private consumers, so they ask for about 400-500 rubles per bottle.

Technical acid is less common in retail and costs about 100 rubles less. The main one is wholesale.

Large enterprises are being purchased. It is for them that the prices indicated at the beginning of the chapter are relevant. The giants do not sell retail.

Accordingly, the cost of the substance in small stores is a reflection of the “appetites” of the store owners.

By the way, about appetite. If the acidity in the stomach is increased, food is digested faster, and you want to eat more often.

This leads to thinness, gastritis and ulcers. People with low acidity are prone to slagging, because food “ferments” in the stomach for a long time and is poorly digested.

This is reflected on the skin, usually in the form of acne and spots. Is there such a problem?

Think not about expensive cosmetics, but about checking your gastrointestinal tract.

Approximate solutions. In most cases, the laboratory has to use hydrochloric, sulfuric and nitric acids. Acids are commercially available in the form of concentrated solutions, the percentage of which is determined by their density.

Acids used in the laboratory are technical and pure. Technical acids contain impurities, and therefore when analytical work are not used.

Concentrated hydrochloric acid smokes in air, so you need to work with it in a fume hood. The most concentrated hydrochloric acid has a density of 1.2 g/cm3 and contains 39.11% hydrogen chloride.

The dilution of the acid is carried out according to the calculation described above.

Example. You need to prepare 1 liter of a 5% solution of hydrochloric acid, using a solution with a density of 1.19 g/cm3. From the reference book we find out that a 5% solution has a density of 1.024 g/cm3; therefore, 1 liter of it will weigh 1.024 * 1000 = 1024 g. This amount should contain pure hydrogen chloride:

An acid with a density of 1.19 g/cm3 contains 37.23% HCl (we also find it from the reference book). To find out how much of this acid should be taken, make up the proportion:

or 137.5/1.19 = 115.5 acid with a density of 1.19 g/cm3. Having measured out 116 ml of acid solution, bring its volume to 1 liter.

Sulfuric acid is also diluted. When diluting it, remember that you need to add acid to the water, and not vice versa. When diluted, strong heating occurs, and if you add water to the acid, it may splash, which is dangerous, since sulfuric acid causes severe burns. If acid gets on clothes or shoes, you should quickly wash the doused area with plenty of water, and then neutralize the acid with sodium carbonate or ammonia solution. In case of contact with the skin of your hands or face, immediately wash the area with plenty of water.

Particular care is required when handling oleum, which is a sulfuric acid monohydrate saturated with sulfuric anhydride SO3. According to the content of the latter, oleum comes in several concentrations.

It should be remembered that with slight cooling, oleum crystallizes and is in a liquid state only when room temperature. In air, it smokes, releasing SO3, which forms sulfuric acid vapor when interacting with air moisture.

It is very difficult to transfer oleum from large to small containers. This operation should be carried out either under draft or in air, but where the resulting sulfuric acid and SO3 cannot have any harmful effect on people and surrounding objects.

If the oleum has hardened, it should first be heated by placing the container with it in a warm room. When the oleum melts and turns into an oily liquid, it must be taken out into the air and then poured into a smaller container, using the method of squeezing with air (dry) or an inert gas (nitrogen).

When nitric acid is mixed with water, heating also occurs (though not as strong as in the case of sulfuric acid), and therefore precautions must be taken when working with it.

Solid organic acids are used in laboratory practice. Handling them is much simpler and more convenient than liquid ones. In this case, care should only be taken to ensure that the acids are not contaminated with anything foreign. If necessary, solid organic acids are purified by recrystallization (see Chapter 15 “Crystallization”),

Precise solutions. Precise acid solutions They are prepared in the same way as approximate ones, with the only difference that at first they strive to obtain a solution of a slightly higher concentration, so that later it can be diluted precisely, according to calculations. For precise solutions, use only chemically pure preparations.

The required amount of concentrated acids is usually taken by volume calculated based on density.

Example. You need to prepare 0.1 and. H2SO4 solution. This means that 1 liter of solution should contain:

An acid with a density of 1.84 g/cmg contains 95.6% H2SO4 n to prepare 1 liter of 0.1 n. of the solution you need to take the following amount (x) of it (in g):

The corresponding volume of acid will be:

Having measured exactly 2.8 ml of acid from the burette, dilute it to 1 liter in a volumetric flask and then titrate with an alkali solution to establish the normality of the resulting solution. If the solution turns out to be more concentrated), the calculated amount of water is added to it from a burette. For example, during titration it was found that 1 ml of 6.1 N. H2SO4 solution contains not 0.0049 g of H2SO4, but 0.0051 g. To calculate the amount of water needed to prepare exactly 0.1 N. solution, make up the proportion:

Calculation shows that this volume is 1041 ml; the solution needs to be added 1041 - 1000 = 41 ml of water. You should also take into account the amount of solution taken for titration. Let 20 ml be taken, which is 20/1000 = 0.02 of the available volume. Therefore, you need to add not 41 ml of water, but less: 41 - (41*0.02) = = 41 -0.8 = 40.2 ml.

* To measure the acid, use a thoroughly dried burette with a ground stopcock. .

The corrected solution should be checked again for the content of the substance taken for dissolution. Accurate solutions of hydrochloric acid are also prepared using the ion exchange method, based on an accurately calculated sample of sodium chloride. The sample calculated and weighed on an analytical balance is dissolved in distilled or demineralized water, and the resulting solution is passed through a chromatographic column filled with a cation exchanger in the H-form. The solution flowing from the column will contain an equivalent amount of HCl.

As a rule, accurate (or titrated) solutions should be stored in tightly closed flasks. A calcium chloride tube must be inserted into the stopper of the vessel, filled with soda lime or ascarite in the case of an alkali solution, and with calcium chloride or simply cotton wool in the case of an acid.

To check the normality of acids, calcined sodium carbonate Na2COs is often used. However, it is hygroscopic and therefore does not fully satisfy the requirements of analysts. It is much more convenient to use acidic potassium carbonate KHCO3 for these purposes, dried in a desiccator over CaCl2.

When titrating, it is useful to use a “witness”, for the preparation of which one drop of acid (if an alkali is being titrated) or alkali (if an acid is being titrated) and as many drops of an indicator solution as added to the titrated solution are added to distilled or demineralized water.

The preparation of empirical, according to the substance being determined, and standard solutions of acids is carried out by calculation using the formulas given for these and the cases described above.

Hydrochloric acid - inorganic substance, a monoprotic acid, one of the most strong acids. Other names are also used: hydrogen chloride, hydrochloric acid, hydrochloric acid.

Properties

Acid in its pure form is a colorless and odorless liquid. Industrial acid usually contains impurities that give it a slightly yellowish tint. Hydrochloric acid is often called “fuming” because it emits hydrogen chloride vapors, which react with moisture in the air and form acid fog.

Very soluble in water. At room temperature, the maximum possible hydrogen chloride content by weight is 38%. An acid concentration greater than 24% is considered concentrated.

Hydrochloric acid actively reacts with metals, oxides, hydroxides, forming salts - chlorides. HCl reacts 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, which results in the formation of a white cheesy precipitate.

Safety precautions

The substance is very caustic, corrodes skin, organic materials, metals and their oxides. When exposed to air, it releases 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 substances of the 2nd degree of danger (highly dangerous), the maximum permissible concentration of the reagent in the air is 0.005 mg/l. You can work with hydrogen chloride only in filter gas masks and protective clothing, including rubber gloves, an apron, and safety shoes.

When acid spills, wash it off with plenty of water or neutralize it with alkaline solutions. Those affected by acid should be taken out of the danger area, rinse their skin and eyes with water or soda solution, and call a doctor.

The chemical reagent can be transported and stored in glass, plastic containers, as well as in metal containers coated on the inside with a rubber layer. The container must be hermetically sealed.

Receipt

On an industrial scale, hydrochloric acid is produced from hydrogen chloride (HCl) gas. Hydrogen chloride itself is produced in two main ways:
- exothermic reaction of chlorine and hydrogen - thus obtaining a high-purity reagent, for example, for the food industry and pharmaceuticals;
- from related industrial gases— an acid based on such HCl is called abgasic.

This is interesting

It was hydrochloric acid that nature “entrusted” with the process of breaking down 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!

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 renewed daily to restore damaged areas. In addition to participating in the process of digesting 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 insufficiency; for anemia to improve the absorption of iron-containing drugs.
— In the food industry it is a food additive, acidity regulator E507, and also an ingredient in seltzer (soda) water. Used in the production of fructose, gelatin, citric acid.
- In the chemical industry - the basis for the production of chlorine, soda, monosodium glutamate, metal chlorides, for example zinc chloride, manganese chloride, ferric chloride; synthesis of organochlorine substances; catalyst in organic syntheses.
— Most of the hydrochloric acid produced in the world is consumed in metallurgy for cleaning workpieces from oxides. For these purposes, an inhibited industrial acid is used, which contains special reaction inhibitors (moderators), due to which the reagent dissolves oxides, but not the metal itself. Metals are also etched with hydrochloric acid; clean them before tinning, soldering, galvanizing.
— Treat the leather before tanning.
— In the mining industry it is in demand for cleaning boreholes from sediments, for processing ores and rock formations.
— In laboratory practice, hydrochloric acid is used as a popular reagent for analytical research and for cleaning vessels from difficult-to-remove contaminants.
— Used in the rubber, pulp and paper industries, and in ferrous metallurgy; for cleaning boilers, pipes, equipment from complex deposits, scale, rust; for cleaning ceramic and metal products.