mineral acid. Fundamentals of mineral acid technology (using sulfuric acid as an example) What applies to mineral acids

acids called chemical compounds containing in its composition hydrogen atoms that can be replaced by metal atoms. In water, most acids (HA) decompose (dissociate) into hydrogen ions (H +) and an acid residue (A -).

ON H + + A -

According to the degree of dissociation in water, there are strong, almost completely decomposing into ions (nitric, hydrochloric, sulfuric), medium (phosphoric, hydrofluoric) and weak acids (acetic, boric) that practically do not dissociate in water. Acids can be detected by changing the color of certain indicator substances. For example, litmus in acids is red, phenolphthalien is colorless, methyl orange is orange.

Acids have a strong effect on the human body and animals, because. they have a water-removing effect and, by changing the alkaline reaction of the protoplasm of a living cell to an acidic one, they precipitate proteins. The effect of acid on a living organism depends on the type and concentration of the acid. Under the action of acids, irritation and complete destruction of tissues can occur.

In contact with acids, many metals corrode. To protect against destruction, acid-resistant metals, alloys, silicate and polymeric materials are used. For these same purposes, special substances are sometimes introduced into acids - inhibitors, which reduce or eliminate the corrosive effect of the acid. Distinguish between organic and inorganic acids.

The scale of production of inorganic acids significantly exceeds organic ones. They are widely used in many industries. Among inorganic acids, sulfuric acid is the most widely used in the national economy.

Sulphuric acid is one of the main products of the chemical industry and is widely used in many industries. It belongs to the number of strong inorganic acids and is the cheapest of them (more than 2 times cheaper than nitric and hydrochloric acids).

The main amount of sulfuric acid is spent on the production of mineral fertilizers (superphosphate, ammonium sulfate, nitrophos, nitrophoska, etc.). The second largest consumer is oil refining, where sulfuric acid is used to purify petroleum products. Large amounts of acid are used in non-ferrous metallurgy, in electroplating, in the production of other acids (hydrochloric, phosphoric, hydrofluoric, boric, chromic, acetic, citric, etc.), to obtain metal sulfates, ethers and esters, starch, sugar, for for tanning leather, for equipping batteries and for many other purposes. Mixed with nitric acid, sulfuric acid is used to nitrate organic compounds in the production of explosives and dyes.

In the art, sulfuric acid is understood to mean any mixture of sulfur oxide (VI) with water. The composition of such "sulfuric acid" can be reflected by the formula

x H 2 O + y SO 3 (where x, y > 0). If the ratio is > 0, they deal with an aqueous solution of sulfuric acid, if 0 - with oleum, a solution of sulfur oxide (VI) in sulfuric acid.

Anhydrous sulfuric acid or monohydrate at 20 0 C is an oily liquid with a density of 1820 kg/m 3 . Crystallization temperature of monohydrate +10, 45 0 С, boiling point +296.2 0 С at atmospheric pressure.

Sulfuric acid mixes with water and sulfur oxide (VI) in any ratio, forming intermediate compounds of the composition H 2 SO 4 * nH 2 O (where n \u003d 4.2.1) and H 2 SO 4 * mSO 3 (where m \u003d 1.2 ). Considering Chemical properties sulfuric acid, one should distinguish between the behavior of dilute and concentrated acids. Thus, a dilute acid reacts with all (with the exception of lead) metals that are to the right of hydrogen in the activity series.

On the surface of lead, in contact with dilute sulfuric acid, a dense acid-insoluble sulfate film is formed, which prevents further dissolution of the metal.

Concentrated sulfuric acid, having a strong oxidizing effect, reacts with metals not directly, but through an intermediate stage of oxide formation. As a result of the interaction, sulfates of the corresponding metals, sulfur oxide (IV) and water are formed.

Under the action of concentrated acid, such metals that are in the activity series after hydrogen, such as copper, mercury, silver, and others, dissolve easily (especially when heated). At the same time, iron, chromium, aluminum and even calcium are not destroyed by concentrated acid, because. oxide films formed on the surface of these metals have a denser structure and prevent direct contact of the metals with the acid. This phenomenon is called passivation.

Concentrated acid and oleum have a high affinity for water. When mixed with water, a large amount of heat is released. The strong water-removing effect of sulfuric acid is manifested in its ability to absorb water vapor from the air. This is the basis for the use of concentrated sulfuric acid for drying gases.

Many organic compounds in contact with concentrated sulfuric acid, losing water, char.

Resistant to the action of sulfuric acid are enamels (up to the boiling point of solutions of any concentration, vinyl plastic (up to 60 0 С under the action of 80% H 2 SO 4), polyisobutylene (up to 20-60 0 С depending on the acid concentration), polyethylene ( up to 80 0 C under the action of 70% acid), fluoroplastic - 4 (up to 250 0 C).When heated to 400 0 C, sulfuric acid almost completely dissociates into water about sulfur oxide (VI).

Sulfuric acid is currently produced in two ways: contact and nitrous, or tower.

The contact method is based on the oxidation reaction of sulfur oxide (IV) to sulfur oxide (VI) occurring on the surface of a solid catalyst

2 SO 2 + O 2 2 SO 3 + Q 1

The resulting sulfur oxide (VI), absorbed by water, turns into sulfuric acid

SO 3 + H 2 O H 2 SO 4 + Q 2

The essence of the nitrous method is the oxidation of sulfur oxide (IV) with a mixture of nitrogen oxides NO 2 and N 2 O 3 in the presence of water. Without analyzing in detail the mechanism of this complex process, we present it with the following scheme:

SO 2 + NO 2 (N 2 O 3) + H 2 O H 2 SO 4 + NO (2NO)

The nitrous method has a number of disadvantages compared to the contact method: firstly, it does not allow obtaining sulfuric acid with a concentration of more than 75%, secondly, the resulting acid contains many impurities and is suitable only for the production of mineral fertilizers, and finally, the production of acid by the nitrous method is associated with release into the atmosphere of a large amount of nitrogen oxides, which have a harmful effect on the environment. In this regard, the construction of sulfuric acid plants operating on the nitrous method has been stopped in our country, and more than 90% of the sulfuric acid produced is obtained at contact plants.

As a raw material for the production of sulfuric acid, in principle, any substance containing sulfur can be used. The most commonly used sulfur pyrite FeS 2 (about 45% of the produced sulfuric acid), elemental sulfur, waste gases from non-ferrous metallurgy plants and gases from oil production and oil refining. In recent years, there has been a tendency to increase the share of off-gases from non-ferrous metallurgy and associated gases from oil production in the total balance of raw materials for the production of sulfuric acid.

Technological process The production of sulfuric acid by the contact method includes four main stages: roasting of sulfur-containing raw materials, purification of roasting gas, contact oxidation of sulfur oxide (IV) and absorption of sulfur oxide (VI).

Considering that the main source of raw materials for the production of sulfuric acid in our country is sulfur pyrites, the schematic diagram of the contact method for the production of sulfuric acid can be simplified as follows (Fig. 1).

1) firing of sulfur-containing raw materials;

2) purification of roasting gas from impurities;

3) contact oxidation of sulfur oxide (IV) to sulfur oxide (VI);

4) absorption of sulfur oxide VI by water and production of sulfuric acid.

Q Dust Impurities Q Catalyst

SO2 purification

Burning

Air

concentrated sulfuric acid

Rice. 1 Schematic diagram of sulfuric acid production

Roasting sulfur pyrite, proceeding according to the reaction equation 4 FeS 2 + 110 2 = 2 Fe 2 O 3 + 8SO 2 + Q, is a typical heterogeneous process. Three types of kilns are used for its implementation: mechanical shelf kilns, pulverized kilns and fluidized bed kilns (CF). The latter are the most efficient and are gradually becoming the main type of equipment for burning pyrites. The optimal conditions for pyrite firing are selected taking into account the experimentally established dependences of the reaction rate, on the particle size of the fired pyrite, temperature and air flow supplied to the furnace.

At the second stage, the roasting gas is cleaned from mechanical impurities and oxides of selenium and arsenic in scrubbers and electrostatic precipitators (stage 2). Contact oxidation of sulfur oxide (IV) to sulfur oxide (VI) (stage 3) is a reversible, heterogeneous-catalytic, exothermic process that proceeds with a decrease in gas volume. Under real conditions, the process of contact oxidation is carried out in a polythermal mode, starting at relatively high temperatures and ending at relatively low temperatures. Shelf contact devices and devices with a fluidized bed of a catalyst have found distribution in industry. Vanadium contact masses, consisting of vanadium(V) oxide deposited on porous supports, turned out to be the most effective catalysts.

The final stage (stage 4) of the process is carried out in packed scrubbers irrigated first with oleum and then with 98.3% sulfuric acid, which has the highest absorption coefficient of SO 3 . The absorption process is carried out at temperatures of 30 ... 60 0 C at atmospheric pressure. The quality of currently produced sulfuric acid is regulated by four state standards. Table 2.1. some technical requirements for sulfuric acid are given by state standards 2184-77 (technical sulfuric acid), 667-73 (sulfuric battery acid), 4204-77 (sulfuric acid) and 14262-78 (special purity sulfuric acid). Each of the GOSTs describes in detail the methods by which the physicochemical properties of sulfuric acid are determined.

Table 1. - Physical and chemical properties of sulfuric acid

GOST	Indicators Physical and chemical properties of sulfuric acid	Appearance	Mass fraction of monohydrate,%	Mass fraction of free sulfur oxide (VI), %	Mass fraction of iron, %, no more	Mass fraction of residue after calcination, %, no more

2184-77	1. Contact improved (highest grade)	-	92,5-94,0	-	0,007	0,02
2. Contact improved (1st grade)	-	92,5-94,0	-	0,015	0,03
3. Contact technical (1st grade)	-	92,5	-	0,02	0,05
4. Contact technical (2nd grade)	-	92,5	-	0,1	-
5. Oleum improved (highest grade)	There are no mechanical impurities	-		0,007	0,02
6. Oleum improved (1st grade)	Oily liquid with opalescence	-		0,01	0,03
7. Oleum technical	-	-		-	-
8. Tower	-		-	0,05	0,3
9. Regenerated	-		-	0,2	0,4
667-73	10. Rechargeable (top grade)	-	92-94	-	0,005	0,02
11. Rechargeable (1st grade)	-	92-94	-	0,006	0,03
12. Rechargeable (2nd grade)	-	92-94	-	0,012	0,04
4204-77	13. Reactive (h)	-	-	-	-	-
14. Reactive (chemically pure)	-	-	-	-	-
15. Reactive (ch.d.a.)	-	-	-	-	-
14262-78	16. Special purity (high purity 20-4)	Indistinguishable from distilled water in a test tube with a diameter of 20 mm	93,5-95,5	-	2*10 -6	5*10 -4
17. Special purity (high quality 11-5)	93,5-95,5	-	3*10 -6	5*10 -4
18. Special purity (high quality 5-5)	93,5-95,5	-	1*10 -5	5*10 -4

Sulphuric acid. Under normal conditions, concentrated sulfuric acid is a heavy oily liquid, colorless and odorless, with a sour "coppery" taste. Mixes up with water in any ratios with release of heat. Sulfuric acid is low volatile, but at temperatures above 50 0 C it is capable of forming sulfuric anhydride vapors, which are more toxic than the acid itself.

In industry, it is produced in the form of a monohydrate - a 98% solution of sulfuric acid; oleum - 20% solution of sulfuric anhydride SO 3 in sulfuric acid; crude sulfuric acid (vitriol) - 93-97% sulfuric acid solution.

Sulfuric acid is used in almost any area of industry: in the production of mineral fertilizers; as an electrolyte in lead batteries; to obtain various mineral acids and salts; in the production of chemical fibers, dyes, smoke-forming and explosive substances; in the oil, metalworking, textile, leather and other industries; in the food industry (food additive E 513), in industrial organic synthesis (in reactions: dehydration, hydration, sulfonation, alkylation, etc.), for the recovery of resins in filters in the production of distilled water.

The main routes of entry of sulfuric acid into the body are oral, inhalation and percutaneous. The lethal dose is considered to be 5-10 g.

In case of inhalation poisoning, shortness of breath is observed, which is accompanied by cough, hoarseness, the development of laryngitis, bronchitis or tracheitis is possible. When inhaled at high concentrations, swelling of the larynx, lungs develops, asphyxia and shock may develop. The latent period of sulfuric acid poisoning can be up to 90 days.

When sulfuric acid gets on the skin, it quickly penetrates deep into the tissues, forming first white, and, with the passage of time, brown-black scabs.

During the pathoanatomical examination of oral poisoning, traces of a chemical burn around the mouth (brown stripes and spots) are observed. The mucous membranes of the mouth, pharynx, esophagus are colored gray-brown, the gastric mucosa is grayish-red.

Qualitative and quantitative analysis for the presence of sulfuric acid.

When examining dialysate for the presence of sulfuric acid, it is distilled over copper filings and the distillate is collected in a receiver containing a solution of iodine in potassium iodide.

A redox reaction takes place in the flask with the formation of sulfurous acid, and then its decomposition to sulfur oxide (II).

Sulfur oxide with water vapor, entering the receiver, interacts with an iodine solution to form sulfuric acid.

During simple distillation, due to the constant presence of chlorides extracted from the biological object, they react with free sulfuric acid to form hydrogen chloride.

Sulfuric acid formed as a result of distillation is detected by the reactions:

ü The reaction of the formation of barium sulfate. The appearance of a white precipitate upon addition of barium chloride indicates the presence of sulfate ions, but does not prove the presence of free sulfuric acid.

ü Lead sulfate reaction. Precipitation of a white precipitate, insoluble in nitric acid, but soluble in alkali solutions and ammonium acetate solution.

ü Reaction with barium rhodisonate. The reaction is based on the fact that sodium rhodizonate with barium salts forms barium rhodizonate, which has a red color. From the addition of sulfuric acid or barium sulfate ions, rhodizonate decomposes, a white precipitate of barium sulfate forms, and the red color disappears.

The reaction is specific for the sulfate ion. Test for the presence of free sulfuric acid.

quantitation sulfuric acid is carried out by alkalimetry. A 0.1 M sodium hydroxide solution is used as a titrant (methyl orange indicator).

Hydrochloric acid. Colorless (technical hydrochloric acid is yellowish due to impurities of Fe, Cl 2, etc.), caustic liquid with a pungent odor, containing 35 - 38% hydrogen chloride. Easily evaporates in air, "smoke" due to the formation of hydrogen chloride with water vapor mist droplets. Miscible with water in any ratio.

The industry produces "battery" hydrochloric acid containing about 37% hydrogen chloride and concentrated hydrochloric acid containing about 25% hydrogen chloride.

It is used in chemical synthesis, hydrometallurgy and electroforming (for processing ores, pickling metals), for cleaning the surface of metals during soldering and tinning, for obtaining chlorides of zinc, manganese, iron and other metals. In a mixture with a surfactant, it is used to clean ceramic and metal products from contamination and disinfection. Registered in the food industry as an acidity regulator and food additive E 507. Hydrochloric acid is a natural component of human gastric juice. Solutions of hydrochloric acid, 0.3 - 0.5%, usually mixed with the enzyme pepsin, are administered orally to patients with insufficient acidity.

The main route of entry of hydrochloric acid is inhalation, less often percutaneous and oral. A lethal dose is considered to be 10-15 g of hydrochloric acid.

When hydrogen chloride is inhaled, irritation of the upper respiratory tract and lungs is observed, manifested by hoarseness, cough, chest pain. In severe cases, death occurs from asphyxia as a result of laryngeal edema or spasm of the glottis after 3-4 hours.

With percutaneous and oral poisoning, the symptoms are similar to those of sulfuric acid poisoning, but to a lesser extent. Serous inflammation with blisters is observed on the skin, the affected areas have a gray-whitish color, the burns are insignificant. When it comes into contact with the mucous membrane of the eye, it causes conjunctivitis, chemical burns, clouding of the cornea.

At autopsy, a grayish or black color of the mucous membranes of the oral cavity, esophagus, stomach and upper intestine is observed. The contents of the stomach is a brown mass. The liver, kidneys and heart are prone to fatty degeneration. The heart muscle is flabby and has a yellowish color.

Qualitative and quantitative analysis for the presence of hydrochloric acid.

An aqueous extract from biological material, or dialysate, is initially examined for the presence of chloride ions. The formation of a copious white precipitate with silver nitrate indicates the need for further testing for free hydrochloric acid.

Due to the possibility of the formation of hydrochloric acid from chlorides in the presence of free sulfuric acid, a test is first carried out for sulfuric acid, and then for hydrochloric acid.

In the study of dialysate for the presence of hydrochloric acid, it, like hydrochloric acid, is obtained by distillation of the dialysate in a sand bath. Initially, water is distilled from the flask into the receiver, and when hydrogen chloride reaches 10% concentration, it begins to distill into the receiver and dissolves in the water present. If possible, the distillation is carried out until all the liquid from the flask has evaporated.

The distillate is examined for the presence of hydrogen chloride by the reactions:

ü Reaction with silver nitrate. The appearance of a white precipitate, soluble in ammonia solution and re-formed upon addition of nitric acid, indicates the presence of chloride ions.

ü Iodine release reaction. When chlorate is added to potassium distillate with slight heating, free chlorine is released, which is detected by the blue color of starch iodine paper.

Quantitation.

The quantitative determination of hydrogen chloride is important in order to judge whether in a given case (for example, in vomit) the introduced acid is present, and not hydrochloric acid of gastric juice (0.1-0.2%), which is usually already present in the contents of the stomach of a corpse. neutralized.

A certain part of the aqueous extract is subjected to distillation, evaporating the contents of the flask, as described above, to dryness. In the distillate, the amount of hydrogen chloride is determined by Volhard titration or by weight, weighing silver chloride.

The Volhard method is not applicable to the quantitative determination of hydrochloric acid if the biological material is susceptible to decay. The resulting hydrogen sulfide reacts with silver nitrate to form a precipitate of silver sulfide (AgS) and distorts the results of the analysis. Therefore, gravimetry is used to quantify hydrochloric acid in stale biological material.

An excess of silver nitrate is added to the solution, the resulting precipitates of silver chloride and silver sulfide are filtered off and treated with 10% ammonia solution to dissolve silver chloride. The ammonia solution is acidified with nitric acid, and the silver chloride precipitate is filtered off, dried and weighed.

Nitric acid. Colorless transparent liquid. Miscible with water in any ratio. When opened, nitric acid emits heavier vapors that form white smoke. Non-combustible, but has the ability to ignite all combustible substances. Able to explode in the presence of vegetable and mineral oils, alcohol.

In industry, it is produced in the form of 50 - 60% and 96 - 98% solutions.

Industrial Application nitric acid: in the production of mineral fertilizers; in the military industry (in the production of explosives, as an oxidizer for rocket fuel, in the synthesis various substances, including poisonous ones); for etching printing forms; in the production of dyes and drugs (nitroglycerin); in jewelry (the main method for determining gold in a gold alloy).

As with the previous acids, the main routes of nitric acid intake are inhalation, percutaneous and oral. A lethal dose is considered to be 8-10 g of nitric acid.

Irritation of the upper respiratory tract and lung tissue leads to the development of toxic pulmonary edema. The latent period is from 3 to 6 hours. In case of inhalation poisoning, cyanosis of the mucous membranes of the eyelids and lips is observed, a large amount of fine bubble foam accumulates in the trachea and bronchi, the lungs are enlarged in volume, the color of the lungs is bluish-red with a large accumulation of foam on the cut. Internal organs plethoric, there is swelling of the pia mater and brain.

Upon contact with the skin, tissues acquire yellow due to decomposition products and nitration. When ingested, poisoning begins with sharp pains in the mouth, pharynx, esophagus, and stomach. Vomiting brown masses with scraps of mucous membrane. Death occurs due to shock or collapse.

At autopsy, the contents of the stomach have a smell of nitrogen oxides, a yellowish color is observed in the circumference and mucous membrane of the mouth, mucous membrane of the digestive tract. The heart muscle and liver are grayish-red in color with a brown tint, flabby.

Qualitative and quantitative analysis for the presence of nitric acid.

To detect nitric acid, the distillation of the dialysate is carried out, as in the case of sulfuric acid, over copper filings, and water is placed in the receiver to capture the nitric oxide (IV) formed in the flask. When nitric acid interacts with copper filings, nitric oxide (II) is formed, which is oxidized to nitric oxide (IV), which reacts with water, resulting in a mixture of nitric and nitrous acids.

The detection of the resulting nitric and nitrous acids is carried out according to the reactions:

ü Reaction with diphenylamine. The reaction is based on the oxidation of diphenylamine with nitric acid, which initially forms colorless diphenylbenzidine, which, upon further oxidation, turns into a blue compound. The reaction is non-specific. The same coloration is given by salts of nitric and nitrous acids, as well as other oxidizing agents.

ü Reaction with brucine. The appearance of a red color indicates the presence of nitric acid.

BRUCIN

ü Reaction with protein to nitric acid (xanthan protein test). Free nitric acid at a sufficient concentration is able to be fixed by proteins and stain them yellow, turning orange from the addition of ammonia. Woolen and silk threads will change their color as a result of this reaction, unlike cotton threads, which remain white.

Picric acid can also give a similar color (yellowing of the threads), however, the color of the dialysate solution will also be yellow.

reaction to nitrous acid. Green coloration upon addition of phenazone solution in the presence of sulfuric acid indicates the presence of nitrous acid in the dialysate.

quantitation nitric acid is carried out by the method of neutralization. A 0.1M sodium hydroxide solution is used as a titrant, the indicator is phenolphthalein.

II. Caustic alkalis.

Caustic alkalis include sodium hydroxide (caustic soda, NaOH), potassium hydroxide (KOH) and calcium hydroxide Ca (OH) 2. A weak base is a solution of ammonia (NH4OH).

Sodium hydroxide(caustic soda, caustic, caustic soda, caustic alkali). White solid crystalline substance. It melts when exposed to air as it attracts moisture. It dissolves well in water with a large release of heat, forming solutions that are soapy to the touch. Soluble in alcohol and glycerin.

Sodium hydroxide is used in most industries and for domestic needs: in the pulp and paper industry; for saponification of fats in the production of soap, shampoos and other detergents; in chemical industries (for the neutralization of acids and acid oxides, as a reagent or catalyst in chemical reactions, in chemical analysis for titration, for etching aluminum and in the production of pure metals, in oil refining for the production of oils); as an agent for dissolving blockages in sewer pipes; in civil defense for decontamination and neutralization of toxic substances; for purification of exhaled air from carbon dioxide; in cooking (for washing and peeling fruits and vegetables, in the production of chocolate and cocoa, drinks, ice cream, coloring caramel, for softening olives and giving them a black color, in the production of bakery products, as food additive E-524.

Routes of entry into the body: oral, inhalation (in the form of dust). The action is especially pronounced in direct contact with the skin or mucous membranes. A pronounced irritating and cauterizing effect develops, deep necrosis due to the formation of loose soluble protein albuminates. A lethal dose is considered to be 10-20 g of sodium hydroxide.

In case of contact with the skin or mucous membranes, a deep burn is typical with the formation of soft scabs and their subsequent scarring. With inhalation damage, an acute inflammatory process of the respiratory tract occurs; possible pneumonia. When sodium hydroxide is ingested (orally), acute inflammation, small ulcers, burns of the mucous membranes of the lips, mouth, esophagus and stomach are observed. Poisoning is accompanied by intense thirst, salivation, bloody vomiting, and in severe cases, internal bleeding develops. Contact with the mucous membrane of the eye is fraught with severe burns, up to the appearance of blindness.

Qualitative and quantitative analysis for the presence of sodium hydroxide.

Detection of sodium hydroxide is carried out by the Na + cation.

ü Reaction with potassium hydroxystibate. In an acetic acid medium, when a solution of potassium hydroxystibate is added to the dialysate, a white crystalline precipitate appears.

The rediscovery of sodium hydroxide is possible due to the formation of methostimonic acid HSbO 3 in an acidic environment, which will precipitate.

ü Reaction with zinc uranyl acetate. In the presence of sodium ions in neutral and acetic acid media, zinc-uranyl acetate forms a greenish-yellow crystalline precipitate. Crystals have the form of octahedrons or tetrahedra.

quantitation sodium hydroxide is carried out by acidimetry, using a 0.1 M solution of hydrochloric acid as a titrant, the indicator is phenolphthalein.

Potassium hydroxide (caustic potash, caustic potash). Colorless, very hygroscopic crystals, but less hygroscopic than sodium hydroxide. Aqueous solutions are strongly alkaline.

Industrial applications: in the food industry (food additive E525), for the production of methane, the absorption of acid gases and the detection of certain cations in solutions, in the production of liquid soaps, for cleaning stainless steel products from grease and other oily substances, as well as residues from mechanical processing , electrolyte in alkaline (alkaline) batteries.

Routes of entry into the body and symptoms of poisoning are similar to sodium hydroxide. Many reactions to the body are more pronounced than sodium hydroxide. A lethal dose is considered to be 10-20 g of potassium hydroxide.

Qualitative and quantitative analysis for the presence of potassium hydroxide.

A pronounced alkaline reaction of the dialysate medium, the absence of carbonates and the presence of potassium ions indicate the presence of potassium hydroxide in the material.

To detect potassium ions in dialysates, the following reactions are used:

ü Reaction with sodium hydrotartrate(NaHC4H4O6) . The precipitation of a white precipitate indicates the presence of K + .

ü Reaction with sodium cobalt nitrite(Na 3 . In the presence of potassium ions, a yellow crystalline precipitate K 2 Na[Co(NO 2) 6] precipitates.

These reagents give precipitation with potassium ions in neutral or slightly acidic solutions, therefore, dialysates with an alkaline reaction are neutralized or adjusted to a slightly acidic reaction (pH = 3-4) with an acetic acid solution before the start of the study.

quantitation potassium hydroxide is carried out by the method of acidimetry, using a 0.1 M solution of hydrochloric acid as a titrant, the indicator is phenolphthalein.

Ammonia is a colorless gas with a pungent odour. It has high volatility. Very volatile. When ammonia is dissolved in water, ammonium hydroxide is formed. Ammonia water (ammonium hydroxide, ammonia water, caustic ammonium, caustic ammonia). Volatile liquid with a sharp specific odor. Toxicity in the air increases dramatically with increasing temperature and humidity.

A 25% ammonia solution is commercially produced. A saturated solution contains 33% ammonia, and ammonia - 10%. Industrial use: in the food industry (food additive E 527); as a fertilizer.

The main route of ammonia intake is inhalation. A lethal dose is 10 - 15 ml of a 33% solution or 25 - 50 ml of a 10% solution.

At high concentrations in the air, there is profuse lacrimation, pain in the eyes, burns of the conjunctiva and cornea, loss of vision. On the part of the respiratory tract - coughing fits, a sharp swelling of the tongue, burns of the mucous membranes of the upper respiratory tract with necrosis, laryngeal edema, bronchitis, bronchospasm. At very high concentrations, paralysis of the central nervous system and rapid death occurs with asphyxia. Death occurs within 10-15 minutes.

At autopsy, bright red membranes of the mouth, pharynx, esophagus, stomach, pulmonary edema, changes in the kidneys (nephrosis and necrosis of the convoluted tubules), hemorrhage in the brain, and the smell of ammonia from the internal organs are observed.

Qualitative and quantitative analysis for the presence of ammonium hydroxide.

Ammonia analysis is carried out if preliminary tests have indicated its possible presence.

Preliminary tests for ammonia are carried out with three indicator papers: red litmus paper, moistened with a solution of copper sulfate and moistened with a solution of lead acetate. The blue color of red litmus paper and paper soaked in copper sulfate solution indicates the presence of ammonia.

The blackening of the "lead" paper indicates the presence of hydrogen sulfide and, consequently, the process of decay. In this case, testing for the presence of ammonia is impractical. The formation of ammonia can also occur in the presence of alkalis (NaOH, KOH), which release ammonia from its salts and protein substances.

Reaction with Nessler's reagent. The yellow-brown or orange-brown color of the precipitated diiododimercurammonium indicates the presence of ammonia in the dialysate. The reaction is not specific since many ions can precipitate this color in alkaline environment in the presence of iodide ions.

quantitation ammonium hydroxide is carried out by acidimetry, using a 0.1 M hydrochloric acid solution as a titrant, the indicator is methyl orange.

HClO, etc.) cannot be isolated as individual compounds; they exist only in solution.

By chemical composition distinguish between anoxic acids (HCl, H 2 S, HF, HCN) and oxygen-containing (oxo acids) (H 2 SO 4, H 3 PO 4). The composition of oxygen-free acids can be described by the formula: H n X, where X is a chemical element that forms an acid (halogen, chalcogen) or an oxygen-free radical: for example, hydrobromic HBr, hydrocyanic HCN, azidic HN 3 acids. In turn, all oxygen-containing acids have a composition that can be expressed by the formula: H n XO m, where X is the chemical element that forms the acid.

Hydrogen atoms in oxyacids are most commonly bonded to oxygen by a polar covalent bond. Acids with several (usually two) tautomeric or isomeric forms are known, which differ in the position of the hydrogen atom:

Separate classes of inorganic acids form compounds in which the atoms of the acid-forming element form molecular homo- and heterogeneous chain structures. Isopoly acids are acids in which the atoms of the acid-forming element are linked through an oxygen atom (oxygen bridge). Examples are polysulphuric H 2 S 2 O 7 and H 2 S 3 O 10 and polychromic acids H 2 Cr 2 O 7 and H 2 Cr 3 O 10 . Acids with several atoms of different acid-forming elements connected through an oxygen atom are called heteropolyacids. There are acids whose molecular structure is formed by a chain of identical acid-forming atoms, for example, in polythionic acids H 2 S n O 6 or in sulfanes H 2 S n, where n≥2.

texvc not found; See math/README for setup help.): \mathsf(HA + H_2O \rightleftarrows H_3O^+ + A^-) Unable to parse expression (executable file texvc not found; See math/README for setup help.): \mathsf(HA \rightarrow H^+ + A^-)(simplified notation)

Acid	Meaning (m - n)	K a
HClO	0	10 −8
H 3 AsO 3	0	10 −10
H 2 SO 3	1	10 −2
H 3 RO 4	1	10 −2
HNO3	2	10 1
H2SO4	2	10 3
HClO 4	3	10 10

This pattern is due to an increase in polarization N-O connections due to the shift of the electron density from the bond to the electronegative oxygen atom along the mobile π-bonds E=O and the delocalization of the electron density in the anion.

Inorganic acids have properties common to all acids, including: coloring of indicators, dissolution of active metals with evolution of hydrogen (except HNO 3), the ability to react with bases and basic oxides to form salts, for example:

Unable to parse expression (executable file texvc not found; See math/README for setup help.): \mathsf(2HCl + Mg \rightarrow MgCl_2 + H_2\uparrow) Unable to parse expression (executable file texvc not found; See math/README for setup help.): \mathsf(HNO_3 + NaOH \rightarrow NaNO_3 + H_2O) Unable to parse expression (executable file texvc not found; See math/README for setup help.): \mathsf(2HCl + CaO \rightarrow CaCl_2 + H_2O)

The number of hydrogen atoms split off from an acid molecule and capable of being replaced by a metal to form a salt is called the basicity of the acid. Acids can be divided into one-, two- and three-basic. Acids with higher basicity are not known.

Many inorganic acids are monobasic: hydrohalic species HHal, nitric HNO 3, chloric HClO 4, thiocyanate HSCN, etc. Sulfuric H 2 SO 4, chromic H 2 CrO 4 , hydrogen sulfide H 2 S are examples of dibasic acids, etc.

Polybasic acids dissociate in steps, each step has its own acidity constant, and each subsequent K a is always less than the previous one by about five orders of magnitude. The dissociation equations for tribasic phosphoric acid are shown below:

Unable to parse expression (executable file texvc not found; See math/README for setup help.): \mathsf(H_3PO_4 \rightleftarrows H^+ + H_2PO_4^- \ \ K_(a1) = 7\cdot 10^(-3)) Unable to parse expression (executable file texvc not found; See math/README for setup help.): \mathsf(H_2PO_4^- \rightleftarrows H^+ + HPO_4^(2-) \ \ K_(a2) = 6\cdot 10^(-8)) Unable to parse expression (executable file texvc not found; See math/README for setup help.): \mathsf(HPO_4^(2-) \rightleftarrows H^+ + PO_4^(3-) \ \ K_(a3) = 1\cdot 10^(-12))

Basicity determines the number of rows of medium and acid salts - acid derivatives.

Only hydrogen atoms that are part of the hydroxy groups -OH are capable of substitution, therefore, for example, orthophosphoric acid H 3 PO 4 forms medium salts - phosphates of the Na 3 PO 4 type, and two series of acidic ones - Na 2 HPO 4 hydrophosphates and NaH 2 PO dihydrophosphates 4 . Whereas, phosphorous acid H 2 (HPO 3) has only two rows - phosphites and hydrophosphites, and hypophosphorous acid H (H 2 PO 2) has only a series of medium salts - hypophosphites.

General methods for obtaining acids

There are many methods for obtaining acids, including general ones, among which the following can be distinguished in industrial and laboratory practice:

The interaction of acid oxides (anhydrides) with water, for example:

Unable to parse expression (executable file texvc not found; See math/README for setup help.): \mathsf(P_2O_5 + 3H_2O \rightarrow 2H_3PO_4) Unable to parse expression (executable file texvc not found; See math/README for setup help.): \mathsf(2CrO_3 + H_2O \rightarrow H_2Cr_2O_7)

The displacement of a more volatile acid from its salt by a less volatile acid, for example:

Unable to parse expression (executable file texvc not found; See math/README for tuning help.): \mathsf(CaF_2 + H_2SO_4 \rightarrow CaSO_4 + 2HF\uparrow) Unable to parse expression (executable file texvc not found; See math/README for setup help.): \mathsf(KNO_3 + H_2SO_4 \rightarrow KHSO_4 + HNO_3\uparrow)

Hydrolysis of halides or salts, for example:

Unable to parse expression (executable file texvc not found; See math/README for setup help.): \mathsf(PCl_5 + 4H_2O \rightarrow H_3PO_4 + 5HCl) Unable to parse expression (executable file texvc not found; See math/README for setup help.): \mathsf(Al_2Se_3 + 6H_2O \rightarrow 2Al(OH)_3 + 3H_2Se)

Synthesis of oxygen-free acids from simple substances

Unable to parse expression (executable file texvc not found; See math/README for setup help.): \mathsf(H_2 + Cl_2 \rightarrow 2HCl)

Ion exchange reactions on the surface of ion exchange resins: chemisorption of cations of dissolved salts and their replacement by H + .

Application

Mineral acids are widely used in metal and woodworking, textile, paintwork, oil and gas and other industries and in scientific research. Among the substances produced in the largest volume are sulfuric, nitric, phosphoric, hydrochloric acids. The total annual production of these acids in the world amounts to hundreds of millions of tons per year.

In metalworking, they are often used to pickle iron and steel and as cleaning agents before welding, plating, painting, or electroplating.

Sulfuric acid, aptly named by D. I. Mendeleev " bread industry”, is used in the production of mineral fertilizers, for the production of other mineral acids and salts, in the production of chemical fibers, dyes, smoke-generating and explosive substances, in the oil, metalworking, textile, leather, food and other industries, in industrial organic synthesis, etc. . P.

Hydrochloric acid is used for acid treatment, purification of tin and tantalum ores, for the production of molasses from starch, for descaling boilers and heat exchange equipment of thermal power plants. It is also used as a tannin in the leather industry.

Nitric acid is used in the production of ammonium nitrate, which is used as a fertilizer and in the manufacture of explosives. In addition, it is used in organic synthesis processes, in metallurgy, in ore flotation and in the processing of spent nuclear fuel.

Orthophosphoric acid is widely used in the production of mineral fertilizers. It is used in soldering as a flux (on oxidized copper, on ferrous metal, on stainless steel). Included in corrosion inhibitors. It is also used in the composition of freons in industrial freezers as a binder.

Peroxo acids, oxygen-containing acids of chlorine, manganese, chromium are used as strong oxidizing agents.

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Literature

Nekrasov B.V., Fundamentals of General Chemistry, 3rd ed., vol. 1-2. M., 1973;
Campbell J., Contemporary general chemistry, per. from English, vol. 1-3, M., 1975;
Bell R., Proton in chemistry, trans. from English, M., 1977;
Hyun D., Inorganic Chemistry, trans. from English, M., 1987.

Notes

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inorganic acids

An excerpt characterizing inorganic acids

The same little man, Hugues de Arcy, stopped in front of Cathars. Impatiently marking time, apparently wanting to finish as soon as possible, he began the selection in a hoarse, cracked voice...
- What is your name?
“Esclarmonde de Pereille,” came the reply.
“Hugues de Arcy, acting on behalf of the King of France. You are accused of heresy Cathar. You know, in accordance with our agreement, which you accepted 15 days ago, in order to be free and save your life, you must renounce your faith and sincerely swear allegiance to the faith of the Roman Catholic Church. You have to say: "I renounce my religion and accept the Catholic religion!".
– I believe in my religion and will never renounce it... – the answer sounded firmly.
"Throw her into the fire!" - the little man shouted contentedly.
Well that's all. Her fragile and short life came to its terrible end. Two people grabbed her and threw her onto a wooden tower, on which a gloomy, insensitive "executor" was waiting, holding thick ropes in his hands. A fire was burning there... Esclarmonde was badly hurt, but then she smiled bitterly to herself - very soon she would have much more pain...
- What is your name? Arcee's poll continued.
Corba de Pereil...
In a short moment, her poor mother was just as roughly tossed beside her.
So, one by one, the Cathars went through a “selection”, and the number of those sentenced was increasing ... All of them could save their lives. All you had to do was “just” lie and deny what you believed in. But no one agreed to pay such a price ...
The flames of the fire cracked and hissed - the damp tree did not want to burn at full power. But the wind grew stronger and from time to time brought burning tongues of fire to one of the convicts. The clothes on the unfortunate person flared up, turning the person into a burning torch... There were screams - apparently, not everyone could endure such pain.

Esclarmonde trembled with cold and fear... No matter how brave she was, the sight of burning friends caused her a real shock... She was completely exhausted and unhappy. She really wanted to call someone for help... But she knew for sure that no one would help or come.
Little Vidomir appeared before my eyes. She will never see him grow... never know if his life will be happy. She was a mother, just once, for a moment, hugging her child... And she will never give birth to Svetozara other children, because her life was ending right now, on this fire... next to others.
Esclarmonde took a deep breath, ignoring the freezing cold. What a pity that there was no sun!.. She so loved to bask under its gentle rays!.. But that day the sky was gloomy, gray and heavy. It said goodbye to them...
Somehow holding back the bitter tears ready to pour, Esclarmonde raised her head high. She will never show how really bad she was! .. No way!!! She'll get through it somehow. The wait wasn't that long...
The mother was nearby. And just about ready to explode...
Father stood like a stone statue, looking at both of them, and there was not a drop of blood in his frozen face ... It seemed that life had left him, carried away to where they would soon go too.
A heart-rending cry was heard nearby - it was my mother who broke out ...
- Korba! Korba, I'm sorry!!! It was the father's cry.
Suddenly Esclarmonde felt a tender, caressing touch... She knew it was the Light of her Dawn. Svetozar... It was he who extended his hand from afar to say the last goodbye... To say that he is with her, that he knows how scared and hurt she will be... He asked her to be strong...
Wild, sharp pain slashed the body - that's it! It's here!!! Burning, roaring flames touched his face. Hair broke out... In a second, the body was on fire with might and main... A sweet, bright girl, almost a child, accepted her death in silence. For a while, she still heard her father screaming wildly, calling her name. Then everything disappeared... Her pure soul went to a kind and right world. Not giving up and not breaking. Exactly the way she wanted.
Suddenly, completely out of place, singing was heard ... It was the churchmen present at the execution who began to sing in order to drown out the screams of the "convicted" who were burning. With voices hoarse from the cold, they sang psalms about the forgiveness and kindness of the Lord...
Finally, at the walls of Montsegur, evening came.
The terrible fire was dying down, sometimes still flashing in the wind with dying, red coals. During the day, the wind had intensified and was now raging at full speed, carrying black clouds of soot and burning along the valley, seasoned with the sweetish smell of burnt human flesh...
By the funeral pyre, bumping into those nearby, a strange, detached man wandered lostly... From time to time, crying out someone's name, he suddenly clutched his head and began to sob loudly, heartbreakingly. The crowd around him parted, respecting someone else's grief. And the man again slowly wandered, not seeing or noticing anything ... He was gray-haired, hunched and tired. Sharp gusts of wind fluttered his long gray hair, tore thin dark clothes from his body... For a moment the man turned around and - oh, gods! .. He was still quite young!!! The emaciated, thin face breathed pain... And the wide-open grey eyes they looked in surprise, as if not understanding where and why he was. Suddenly, the man screamed wildly and... rushed straight into the fire!.. Or rather, into what was left of him... The people standing nearby tried to grab his hand, but did not have time. The man collapsed on his face on the burning red coals, clutching something colored to his chest...
And he didn't breathe.
Finally, somehow dragging him away from the fire, those around him saw what he was holding tightly in his thin, frozen fist ... It was a bright hairband, which young Occitan brides wore before the wedding ... Which meant - only just a few hours ago, he was still a happy young groom ...
The wind still disturbed his gray long hair during the day, quietly playing in the burnt strands ... But the man no longer felt or heard anything. Having regained his beloved, he walked with her hand in hand along the sparkling star road of Qatar, meeting their new starry future ... He was very happy again.
Still wandering around the fading fire, people with faces frozen in grief were looking for the remains of their relatives and friends ... Likewise, not feeling the piercing wind and cold, they rolled out the dying bones of their sons, daughters, sisters and brothers, wives and husbands from the ashes. ... Or even just friends... From time to time, someone weeping raised a ring blackened in the fire... a half-burnt shoe... and even a doll's head, which, having rolled to the side, did not have time to completely burn out...
The same little man, Hugues de Arcy, was very pleased. It was finally over - the Cathar heretics were dead. Now he could safely go home. Shouting to the knight frozen on guard to bring his horse, Arsi turned to the soldiers sitting by the fire to give them final orders. His mood was joyful and upbeat - the mission, which had dragged on for many months, finally came to a "happy" end... His duty was fulfilled. And he could honestly be proud of himself. In a short moment, the rapid clatter of horse hooves was already heard in the distance - the seneschal of the city of Carcassonne hurried home, where a plentiful hot supper and a warm fireplace were waiting for him to warm his frozen, road-weary body.
On the high mountain of Montsegur, the loud and mournful cry of the eagles was heard - they saw off their faithful friends and owners on their last journey ... The eagles cried very loudly ... In the village of Montsegur, people timidly closed the doors. The cry of the eagles resounded throughout the valley. They mourned...

The terrible end of the wonderful empire of Cathar - the empire of Light and Love, Goodness and Knowledge - has come to an end...
Somewhere in the depths of the Occitan mountains there were still runaway Cathars. They hid with their families in the caves of Lombriv and Ornolak, unable to decide what to do next... Having lost the last Perfect Ones, they felt like children who no longer had support.
They were driven.
They were game, for the capture of which great rewards were given.

And yet, the Cathars did not give up yet ... Having moved to the caves, they felt at home there. They knew every turn, every crevice there, so it was almost impossible to track them down. Although the servants of the king and the church tried with might and main, hoping for the promised rewards. They snooped around in the caves, not knowing exactly where they should look. They got lost and died... And some lost ones went crazy, unable to find their way back to the open and familiar sunny world...
The pursuers were especially afraid of the Sakani cave - it ended with six separate passages, zigzags leading straight down. No one knew the real depth of these moves. There were legends that one of those passages led straight to the underground city of the Gods, into which not a single person dared to descend.
After waiting a little, the Pope became furious. The Cathars did not want to disappear in any way!.. This small group of exhausted and incomprehensible people did not give up!.. Despite the losses, despite the hardships, in spite of everything - they still LIVED. And Papa was afraid of them... He didn't understand them. What motivated these strange, proud, impregnable people?! Why did they not give up, seeing that they had no chance of salvation? .. Dad wanted them to disappear. So that not a single damned Cathar remains on earth! .. Unable to think of anything better, he ordered hordes of dogs to be sent into the caves ...
The knights are alive. Now everything seemed simple and easy - they did not have to come up with plans to capture the "infidels". They went into the caves "armed" with dozens of trained hunting dogs, who were supposed to lead them to the very heart of the refuge of the Qatari fugitives. Everything was simple. It only remained to wait a little. Compared to the siege of Montsegur, it was a trifle ...
The caves accepted Cathars, opening their dark, wet embraces for them... The life of the fugitives became difficult and lonely. Rather, it was like survival ... Although there were still very, very many who wanted to help the fugitives. In the small towns of Occitania, such as the principality de Foix (de Foix), Castellum de Verdunum (Castellum de Verdunum) and others, the Cathars still lived under the cover of local seniors. Only now they no longer gathered openly, trying to be more careful, because the Pope's bloodhounds did not agree to calm down, wanting at all costs to exterminate this Occitan "heresy" hiding throughout the country ...
“Be diligent in exterminating heresy by any means! God will inspire you!” - the call of the Pope to the crusaders sounded. And the messengers of the church really tried...
- Tell me, Sever, of those who went into the caves, did anyone live to see the day when it was possible, without fear, to go to the surface? Has anyone managed to save their lives?
– Unfortunately, no, Isidora. The Montsegur Cathars did not survive... Although, as I just told you, there were other Cathars that existed in Occitania for quite a long time. Only a century later the last Qatar was destroyed there. But their life was already completely different, much more secretive and dangerous. Frightened by the Inquisition, people betrayed them, wanting to save their lives. Therefore, some of the remaining Cathars moved to the caves. Someone settled in the woods. But it was already later, and they were much more prepared for such a life. Those whose relatives and friends died in Montsegur did not want to live long with their pain ... Deeply grieving for the dead, tired of hatred and persecution, they finally decided to reunite with them in that other, much kinder and purer life . There were about five hundred of them, including several old people and children. And there were four Perfect Ones with them, who came to the rescue from a neighboring town.
On the night of their voluntarily "departure" from the unjust and evil material world, all the Cathars went outside to breathe in the wonderful spring air for the last time, to once again look at the familiar radiance of the distant stars they loved so much... where their tired ones will fly away very soon, tormented Qatari soul.
The night was sweet, quiet and warm. The earth was fragrant with the smells of acacias, blossoming cherries and thyme... People inhaled the intoxicating aroma, experiencing the most real childish pleasure!.. For almost three long months they did not see a clear night sky, they did not breathe real air. After all, in spite of everything, no matter what happened on it, it was their land! .. Their dear and beloved Occitania. Only now it was filled with the hordes of the Devil, from which there was no escape.
Without saying a word, the Cathars turned towards Montsegur. They wanted to take one last look at their HOUSE. To the sacred Temple of the Sun for each of them. A strange, long procession of thin, emaciated people rose unexpectedly easily to the highest of the Cathar castles. It was as if nature itself helped them!.. Or perhaps they were the souls of those with whom they were going to meet very soon?
At the foot of Montsegur, a small part of the crusader army was located. Apparently, the holy fathers were still afraid that the crazy Cathars might return. And they were guarding... A sad column, silent ghosts, passed next to the sleeping guards - no one even moved...
“They used the opaque, didn’t they?” I asked in surprise. – Did all the Cathars know how to do this? ..
No, Isidora. You forgot that the Perfect Ones were with them,” Sever replied and calmly continued on.
When they reached the top, people stopped. In the light of the moon, the ruins of Montsegur looked ominous and unusual. It was as if every stone, soaked in the blood and pain of the dead Qatar, called for revenge on the newcomers ... And although there was dead silence around, it seemed to people that they still heard the death cries of their relatives and friends, who were burning in the flames of the terrifying "cleansing" papal fire . Montsegur towered over them, formidable and ... useless to anyone, like a wounded beast left to die alone ...
The walls of the castle still remembered Svetodar and Magdalena, the children's laughter of Beloyar and the golden-haired Vesta... The castle remembered the wonderful years of Qatar, filled with joy and love. He remembered the kind and bright people who came here under his protection. Now it was no more. The walls stood bare and alien, as if the big, kind soul of Montsegur had flown away with the souls of the burned Cathars ...

The Cathars looked at the familiar stars – from here they seemed so big and close!.. And they knew that very soon these stars would become their new Home. And the stars looked down on their lost children and smiled affectionately, preparing to receive their lonely souls.
In the morning, all the Cathars gathered in a huge, low cave, which was located directly above their beloved - the “cathedral” ... There, once upon a time, Golden Mary taught KNOWLEDGE ... New Perfect Ones gathered there ... There the Light and Good Peace Qatar.
And now, when they returned here only as "fragments" of this wonderful world, they wanted to be closer to the past, which was no longer possible to return... The Perfect Ones quietly gave Purification (consolementum) to each of those present, affectionately laying their magic hands on their tired , drooping heads. Until all the "leaving" were finally ready.
In complete silence, people in turn lay down directly on the stone floor, crossing their thin arms over their chests, and quite calmly closed their eyes, as if they were just going to sleep ... Mothers hugged their children, not wanting to part with them. In another moment, the entire huge hall turned into a quiet tomb of five hundred good people who fell asleep forever... Qatar. Faithful and Bright followers of Radomir and Magdalene.
Their souls amicably flew away to where their proud, courageous "brothers" were waiting. Where the world was gentle and kind. Where you no longer had to be afraid that, by someone’s evil, bloodthirsty will, your throat would be cut or simply thrown into the “cleansing” papal fire.
A sharp pain squeezed my heart ... Tears flowed down my cheeks in hot streams, but I did not even notice them. Bright, beautiful and pure people passed away... of their own free will. They left so as not to surrender to the killers. To leave the way they wanted to. In order not to drag out a miserable, wandering life in their own proud and native land - Occitania.
“Why did they do it, Sever? Why didn't they fight?
- Fought - with what, Isidora? Their fight was completely lost. They simply chose HOW they wanted to leave.
– But they left by suicide!.. Isn't that punishable by karma? Didn't that make them suffer the same there in that other world?
– No, Isidora... They just “left”, taking their souls out of the physical body. And this is the most natural process. They did not use violence. They just "left".
With deep sadness, I looked at this terrible tomb, in the cold, perfect silence of which falling drops rang from time to time. It was nature that began to slowly create its eternal shroud - a tribute to the dead ... So, in years, drop by drop, each body will gradually turn into a stone tomb, not allowing anyone to mock the dead ...

MINERAL ACID

MINERAL ACID, a strong inorganic acid, such as hydrochloric (HCl), NITRIC (HNO 3) or SULFURIC ACID (H 2 SO 4).

Scientific and technical encyclopedic dictionary.

See what "MINERAL ACID" is in other dictionaries:

mineral acid- inorganic acid ...

Corrosive mineral acid HN03; in concentrated form can cause severe skin burns. Swallowing acid results in a sharp, burning pain and ulceration of the mouth, pharynx, esophagus, and stomach. For treatment immediately ... ... medical terms

NITRIC ACID- (nitric acid) caustic mineral acid HN03; in concentrated form can cause severe skin burns. Swallowing acid results in a sharp, burning pain and ulceration of the mouth, pharynx, esophagus, and stomach. For treatment... Explanatory Dictionary of Medicine

Mineral water water containing in its composition dissolved salts, trace elements, as well as some biologically active components. Among mineral waters, mineral natural drinking waters are distinguished, mineral waters for outdoor ... ... Wikipedia

inorganic acid- mineral acid... Dictionary of chemical synonyms I

GOST 4640-93: Mineral wool. Specifications- Terminology GOST 4640 93: Mineral wool. Specifications original document: 7.2 Determination of water resistance (pH) 7.2.1 Apparatus, equipment, reagents Chamber electric furnace, providing a heating temperature of up to 600 ° C and automatic ... ... Dictionary-reference book of terms of normative and technical documentation

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MINERAL, mineral, mineral. 1. adj. to the mineral. mineral acid. Mineral wealth of the USSR. mineral kingdom. 2. Containing minerals. Mineral water. Mineral source. mineral salt. || Extracted from minerals. ... ... Explanatory Dictionary of Ushakov

Asian, or Indian (cholera asiatica, ch. indica), is an acute contagious contagious disease. As can be seen from the name, the birthplace of X. is Asia; here it dominates endemically in Bengal on the lower reaches of the Ganges and the Brahmaputra; ... ...

The general name usually applied to all those chem. reactions in which water is added. These reactions are extremely numerous and varied, they take place everywhere in nature and are constantly used both in the laboratory ... ... encyclopedic Dictionary F. Brockhaus and I.A. Efron

Hydroboric acid is an inorganic acid. The chemical name is hydrogen tetrafluoroborate; formula H.

In production, it is obtained by chemical synthesis of hydrofluoric acid with boron oxide or hydroxide, as well as by dissolving boron trifluoride BF3 in water. In the laboratory, this acid can be obtained by mixing dry boric acid and a 40% hydrofluoric acid solution. The reaction is exothermic. Requires safety measures: the solution is poured into the powder gradually, with constant stirring. For mixing, use a stick made of ebonite or vinyl plastic. The procedure is carried out in a fume hood.

Properties

Under normal conditions, an acid can exist only in solutions (in water, toluene, etc.). miscible with water, soluble in ethyl alcohol. In its pure form, the compound is chemically unstable. Solutions are clear, colorless or may be slightly yellowish. The smell is absent or weak, specific, acidic. Hot solutions decompose to form toxic oxofluoroboric acids. Toxic to humans and the environment. Corrosive to fabrics, corrosive to metals. Does not burn, does not explode.

Chemically, it is a very strong acid. Interacts with metals and alkalis to form salts - tetrafluoroborates. The reaction with alkalis proceeds violently. Easily reacts with metal salts and oxides, cyanides, ammonium salts, urea, with many organic compounds, for example, with diazo compounds (containing an organic radical connected to a nitrogen molecule), propylene, formaldehyde, ammonia. Reacts vigorously with oxidizing agents.

Precautionary measures

The substance belongs to the second hazard class. It is non-flammable, but releases dangerous gases such as hydrogen fluoride and fluorine when heated. Reaction with an oxidizing agent can lead to ignition and even explosion. Interaction with metal leads to the release of flammable hydrogen. Sealed containers with acid can explode when heated due to the gases formed during decomposition.

The fire, in the zone of which there are containers with acid, can be extinguished with water, carbon dioxide, powder fire extinguishers. Every precaution should be taken to prevent leakage of the reagent into the environment.

Being strong acid, hydrogen tetrafluoroborate is dangerous to humans: it irritates the respiratory tract, causes severe, poorly curable chemical burns upon contact with skin and mucous membranes. Swallowing may be fatal. The products of chemical reactions with hydroboric acid are often toxic if inhaled.

The victim from contact with the reagent should be taken out to fresh air, the affected areas should be thoroughly washed with water, and artificial respiration should be performed. Be sure to call an ambulance.

The working room must be equipped with general ventilation. Employees must use a full set of protective equipment: self-contained breathing apparatus with air filtration; clothing recommended for contact with this acid; tight-fitting goggles; corrosion resistant rubber gloves. The use of contact lenses is not recommended.

Can be stored in glass jars at room temperature. Store in warehouses at a temperature not exceeding +30 ° C in sealed plastic containers.

When spilling, the acid is neutralized with calcium carbonate, industrial soda (sodium carbonate), quicklime (calcium oxide).

Waste disposal must be carried out by organizations that have the appropriate license.

Application