Hydrochloric acid - physical properties. Preparation and standardization of hydrochloric acid solution

For safety and ease of use, it is recommended to buy the acid as diluted as possible, but sometimes you have to dilute it even more at home. Don't forget to wear protective equipment for your body and face, as concentrated acids cause severe chemical burns. To calculate the required amount of acid and water, you will need to know the molarity (M) of the acid and the molarity of the solution you need to obtain.

Steps

How to calculate the formula

Explore what you already have. Look for the acid concentration designation on the packaging or in the task description. This value is usually indicated as molarity, or molar concentration (M for short). For example, 6M acid contains 6 moles of acid molecules per liter. Let's call this initial concentration C 1.

• The formula will also use the value V 1. This is the volume of acid we will add to the water. We likely won't need the entire bottle of acid, although we don't know the exact amount yet.

1. Decide what the result should be. The required concentration and volume of acid are usually indicated in the text of the chemistry problem. For example, we need to dilute the acid to 2M, and we will need 0.5 liters of water. Let us denote the required concentration as C 2, and the required volume is as V 2.

   • If you are given other units, first convert them to molarity units (moles per liter) and liters.
   • If you don't know what concentration or volume of acid is needed, ask a teacher or someone knowledgeable about chemistry.

2. Write a formula to calculate the concentration. Each time you dilute an acid, you will use the following formula: C 1 V 1 = C 2 V 2. This means that the original concentration of a solution multiplied by its volume equals the concentration of the diluted solution multiplied by its volume. We know that this is true because the concentration times the volume equals the total amount of acid, and the total amount of acid will remain the same.

   • Using the data from the example, we write this formula as (6M)(V 1)=(2M)(0.5L).

3. Solve equation V 1. The V 1 value will tell us how much concentrated acid we need to get the desired concentration and volume. Let's rewrite the formula as V 1 =(C 2 V 2)/(C 1), then substitute the known numbers.

   • In our example, we get V 1 =((2M)(0.5L))/(6M). This equals approximately 167 milliliters.

4. Calculate the required amount of water. Knowing V 1, that is, the available volume of acid, and V 2, that is, the amount of solution that you will get, you can easily calculate how much water you will need. V 2 - V 1 = required volume of water.

   • In our case, we want to get 0.167 liters of acid per 0.5 liter of water. We need 0.5 liters - 0.167 liters = 0.333 liters, that is, 333 milliliters.

5. Wear safety glasses, gloves and a gown. You will need special glasses that will cover the sides of your eyes as well. To avoid burning your skin or burning through your clothing, wear gloves and a robe or apron.

   Work in a well-ventilated area. If possible, work under a switched-on hood - this will prevent acid vapors from harming you and surrounding objects. If you don't have a hood, open all windows and doors or turn on a fan.

6. Find out where the source of running water is. If the acid gets into your eyes or skin, you will need to rinse the affected area under cool running water for 15-20 minutes. Don't start work until you know where the nearest sink is.

   • When rinsing your eyes, keep them open. Look up, down, to the sides so that your eyes are washed from all sides.

7. Know what to do if you spill acid. You can buy a special kit for collecting spilled acid, which will include everything you need, or purchase neutralizers and absorbents separately. The process described below is applicable to hydrochloric, sulfuric, nitric and phosphoric acids. Other acids may require different handling.

   • Ventilate the room by opening windows and doors and turning on the hood and fan.
   • Apply A little sodium carbonate (soda), sodium bicarbonate, or calcium carbonate onto the outer edges of the puddle, ensuring that the acid does not splash.
   • Gradually pour the entire puddle towards the center until you cover it entirely with the neutralizing substance.
   • Mix thoroughly with a plastic stick. Check the pH value of the puddle with litmus paper. Add more neutralizing agent if the reading is greater than 6-8, then rinse the area with plenty of water.

How to dilute acid

1. Cool the water with luda. This should only be done if you will be working with high concentration acids, for example, 18M sulfuric acid or 12M hydrochloric acid. Pour water into a container and place the container on ice for at least 20 minutes.

   • Most often, water at room temperature is sufficient.

2. Pour distilled water into a large flask. For applications requiring extreme precision (such as titrimetric analysis), use a volumetric flask. For all other purposes, a regular conical flask will do. The container must fit the entire required volume of liquid, and there must also be room so that the liquid does not spill.

   • If the capacity of the container is known, there is no need to accurately measure the amount of water.

3. Add a small amount of acid. If you are working with a small amount of water, use a graduated or measuring pipette with a rubber tip. If the volume is large, insert a funnel into the flask and carefully pour the acid in small portions with a pipette.

   • Do not use pipettes in the chemistry laboratory that require air to be drawn in through the mouth.

Hydrochloric acid is an inorganic substance, a 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. 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 accompanying industrial gases - acid based on such HCl is called exhaust gas.

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 ferrous metallurgy; for cleaning boilers, pipes, equipment from complex deposits, scale, rust; for cleaning ceramic and metal products.

Hydrochloric acid (hydrochloric acid, an aqueous solution of hydrogen chloride), known as HCl, is a caustic chemical compound. Since ancient times, people have been using this colorless liquid for various purposes, which emits a light smoke in the open air.

Properties of a chemical compound

HCl is used in various areas of human activity. It dissolves metals and their oxides, is absorbed in benzene, ether and water, and does not destroy fluoroplastic, glass, ceramics and graphite. Its safe use is possible when stored and operated in the correct conditions, in compliance with all safety standards.

Chemically pure (CP) hydrochloric acid is formed during gaseous synthesis from chlorine and hydrogen, giving hydrogen chloride. It is absorbed in water, resulting in a solution containing 38-39% HCl at +18 C. An aqueous solution of hydrogen chloride is used in various areas of human activity. The price of chemically pure hydrochloric acid is variable and depends on many components.

Areas of application of aqueous hydrogen chloride solution

The use of hydrochloric acid has become widespread due to its chemical and physical properties:

• in metallurgy, in the production of manganese, iron and zinc, technological processes, metal purification;
• in galvanoplasty - during etching and pickling;
• in the production of soda water to regulate acidity, in the production of alcoholic beverages and syrups in the food industry;
• for leather processing in light industry;
• when purifying non-drinking water;
• for optimization of oil wells in the oil industry;
• in radio engineering and electronics.

Hydrochloric acid (HCl) in medicine

The most famous property of hydrochloric acid solution is the equalization of the acid-base balance in the human body. Low stomach acidity is treated with a weak solution or drugs. This optimizes the digestion of food and helps fight germs and bacteria that penetrate from the outside. HCl hydrochloric acid helps normalize low levels of gastric acidity and optimizes protein digestion.

Oncology uses HCl to treat tumors and slow down their progression. Hydrochloric acid preparations are prescribed for the prevention of stomach cancer, rheumatoid arthritis, diabetes, asthma, urticaria, cholelithiasis and others. In folk medicine, hemorrhoids are treated with a weak acid solution.

You can find out more about the properties and types of hydrochloric acid.

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

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

Zn + 2HCl = ZnCl 2 + H 2

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

Application of hydrochloric acid

Hydrochloric acid is widely used in industry for extracting metals from ores, etching metals, etc. It is also used in the manufacture of soldering fluid, in the deposition of silver, and as a component of aqua regia.

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

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

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

Hydrochloric acid poisoning

HCl is poisonous. Poisoning usually occurs through fog formed when gas interacts with water vapor in the air. HCl is also absorbed on the mucous membranes with the formation of acid, causing severe irritation. With prolonged work in an HCl atmosphere, catarrh of the respiratory tract, tooth decay, ulceration of the nasal mucosa, and gastrointestinal disorders are observed. The permissible content of HCl in the air of working premises is no more than 0.005 mg/l. For protection, use a gas mask, safety glasses, rubber gloves, shoes, and an apron.

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

Household use of hydrochloric acid

Concentrated “hodgepodge” is mixed with water in any proportion for household needs. A strong solution of this inorganic acid can easily clean earthenware plumbing fixtures from limescale and rust, while a weaker solution can remove stains of rust, ink, and berry juice from fabrics.

If you look closely, the Toilet Duck toilet cleaner says that it contains hydrochloric acid, so you need to work with it wearing rubber gloves and protecting your eyes from splashes.

In addition, no person’s life is unthinkable without this acid - it is contained in the stomach and it is thanks to it that food that enters the stomach dissolves (digests).

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

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

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

HYDROCHLORIC ACID (hydrochloric acid) - a strong monobasic acid, a solution of hydrogen chloride HCl in water, is one of the most important components of gastric juice; in medicine it is used as a medicine for insufficiency of the secretory function of the stomach. S. to. is one of the most commonly used chemicals. reagents used in biochemical, sanitary and hygienic and clinical diagnostic laboratories. In dentistry, 10% S. solution is used for teeth whitening in case of fluorosis (see Teeth whitening). S. to. is used to produce alcohol, glucose, sugar, organic dyes, chlorides, gelatin and glue, in pharmaceuticals. industry, in tanning and dyeing leather, saponification of fats, in the production of activated carbon, dyeing fabrics, etching and soldering of metals, in hydrometallurgical processes for cleaning boreholes from deposits of carbonates, oxides and other sediments, in electroplating, etc.

S. to. for people who come into contact with it in the production process, represents a significant occupational hazard.

S. k. was known back in the 15th century. Its discovery is attributed to him. alchemist Valentin. For a long time it was believed that S. to. is an oxygen compound of a hypothetical chemical. element muria (hence one of its names - acidum muriaticum). Chem. the structure of the S. k. was finally established only in the first half of the 19th century. Davy (N. Davy) and J. Gay-Lussac.

In nature, free sodium chloride practically does not occur, but its salts sodium chloride (see Table salt), potassium chloride (see), magnesium chloride (see), calcium chloride (see), etc. are very widespread.

Hydrogen chloride HCl under normal conditions is a colorless gas with a specific pungent odor; when released into humid air, it “smoke” strongly, forming tiny droplets of aerosol S. to. Hydrogen chloride is toxic. Weight (mass) of 1 liter of gas at 0° and 760 mm Hg. Art. equal to 1.6391 g, air density 1.268. Liquid hydrogen chloride boils at -84.8° (760 mmHg) and solidifies at -114.2°. Hydrogen chloride dissolves well in water, releasing heat and forming hydrogen chloride; its solubility in water (g/100 g H20): 82.3 (0°), 72.1 (20°), 67.3 (30°), 63.3 (40°), 59.6 (50° ), 56.1 (60°).

S. to. is a colorless transparent liquid with a pungent odor of hydrogen chloride; impurities of iron, chlorine or other substances color the soda yellowish-greenish.

The approximate value of S. concentration as a percentage can be found if the beat. reduce the weight of the S. by one and multiply the resulting number by 200; for example, if ud. S.'s weight is 1.1341, then its concentration is 26.8%, i.e. (1.1341 - 1) 200.

S. K. is chemically very active. It dissolves with the release of hydrogen all metals that have a negative normal potential (see Physical and chemical potentials), converts many metal oxides and hydroxides into chlorides and releases free compounds from salts such as phosphates, silicates, borates, etc.

In a mixture with nitrogen (3:1), the so-called. aqua regia, S. reacts with gold, platinum and other chemically inert metals, forming complex ions (AuCl4, PtCl6, etc.). Under the influence of oxidizing agents, S. is oxidized to chlorine (see).

S. to. reacts with many organic substances, for example, proteins, carbohydrates, etc. Certain aromatic amines, natural and synthetic alkaloids and other organic compounds of a basic nature form salts with S. to. hydrochlorides. Paper, cotton, linen, and many artificial fibers are destroyed under the influence of synthetic acid.

The main method of producing hydrogen chloride is synthesis from chlorine and hydrogen. The synthesis of hydrogen chloride proceeds in accordance with the reaction H2 + 2C1-^2HCl + 44.126 kcal. Other methods for producing hydrogen chloride are the chlorination of organic compounds, dehydrochlorination of organic chlorine derivatives and the hydrolysis of certain inorganic compounds with the elimination of hydrogen chloride. Less often, in the lab. In practice, they use the old method of producing hydrogen chloride by reacting table salt with sulfuric acid.

A characteristic reaction to S. and its salts is the formation of a white cheesy precipitate of silver chloride AgCl, soluble in an excess of aqueous ammonia solution:

HCl + AgN03 - AgCl + HN03; AgCl + 2NH4OH - [Ag (NHs)2] Cl + + 2H20.

Store S. to. in glass containers with ground-in stoppers in a cool room.

In 1897, I. P. Pavlov established that the parietal cells of the gastric glands of humans and other mammals secrete S. to a constant concentration. It is assumed that the mechanism of S.'s secretion consists of the transfer of H+ ions by a specific carrier to the outer surface of the apical membrane of the intracellular tubules of the parietal cells and their entry after additional conversion into gastric juice (see). C1~ ions from the blood penetrate into the parietal cell while simultaneously transporting the bicarbonate ion HCO in the opposite direction. Due to this, C1~ ions enter the parietal cell against the concentration gradient and from it into the gastric juice. Parietal cells secrete solution

S. to., the concentration of which is approx. 160 mmol!l.

Bibliography: Volfkovich S.I., Egorov A.P. and Epstein D.A. General chemical technology, vol. 1, p. 491 and others, M.-L., 1952; Harmful substances in industry, ed. N.V. Lazarev and I.D. Gadaskina, vol. 3, p. 41, L., 1977; Nekrasov B.V. Fundamentals of general chemistry, vol. 1 - 2, M., 1973; Emergency care for acute poisoning, Handbook of toxicology, ed. S. N. Golikova, p. 197, M., 1977; Fundamentals of Forensic Medicine, ed. N.V. Popova, p. 380, M.-L., 1938; Radbil O. S. Pharmacological basis for the treatment of diseases of the digestive system, p. 232, M., 1976; Rem and G. Course of inorganic chemistry, trans. with German, vol. 1, p. 844, M., 1963; Guide to forensic medical examination of poisonings, ed. R.V. Berezhny et al., p. 63, M., 1980.

N. G. Budkovskaya; N. V. Korobov (pharm.), A. F. Rubtsov (judgment).