SECTION II. INORGANIC CHEMISTRY
9. Non-metallic elements and their connections. Nonmetals
9.2. Halogens
9.2.2. Hydrogen chloride. Chloride acid
Hydrogen chloride (hydrogen chloride)
The hydrogen chloride molecule is covalent, linear, polar, with one a - communication. The electronegative Chlorine atom displaces the joint electron cloud in its direction:
Molecular crystal lattices of solid hydrogen chloride. The oxidation state of Chlorine is the lowest (-1).
Physical properties of hydrogen chloride
NS l - a colorless gas with an unpleasant pungent odor, heavier than air, highly soluble in water. It smokes in the air because droplets of acid are formed with water vapor, which is in humid air. Up to 500 volumes of NS are dissolved in one volume of water l , in this case chloride acid is formed with maximum mass fraction hydrogen chloride 38- 40%. Chlorine water is a rather toxic substance and irritates the respiratory tract.
Extraction of hydrogen chloride
In the laboratory, chlorinated water is produced by the action of concentrated sulfuric acid on solid sodium chloride (when heated):
If an excess of sulfuric acid is used, then acid salt- sodium hydrogen sulfate:
In industry, chlorinated water is produced by burning hydrogen in an atmosphere of chlorine:
Chloride acid
Aqueous solution Hydrogen chloride is called chloric acid. In the human body, chloride acid is secreted by the cells of the gastric mucosa and promotes the digestion of proteins by pepsin (creates an acidic environment necessary for the functioning of the enzyme).
It is a colorless, volatile liquid. Concentrated chloric acid “smoke” in air because hydrogen chloride molecules are released from the solution. Chloride acid is a strong, monobasic acid. The degree of its dissociation in dilute solutions exceeds 90%:
Chemical properties
1. Chloride acid exhibits general properties acids: reacts with metals that are located in the vitiscuval series to hydrogen, interacts with basic and amphoteric oxides, with grounds and amphoteric hydroxides, with salts:
When an acid interacts with rich acid bases, the formation of basic salts is possible:
A white cheesy precipitate appears AgCl. This qualitative reaction to chloride ion C l - . Argentum chloride, unlike other insoluble salts AgBr, Agl (yellow and yellow in color, respectively), dissolves in excess NH3:
Perchloric acid(formula HClO4) is a monobasic anhydrous acid. Contains chlorine (Cl) in highest degree oxidation, for this reason it is the strongest oxidizing agent. Explosive.
Properties of perchloric acid
1. It is a volatile liquid without color, smokes strongly in the air, and is monomeric in vapor. Unstable and very reactionary. This acid is characterized by autodehydration:
3HClO4 = H3O+ (cation) + ClO- (anion) + Cl2O7 (chlorine oxide)
2. This substance is highly soluble in chlorine and organofluorine solvents, such as CH2Cl2 (methylene chloride), CHCl3 (chloroform) and others. Miscible with other solvents, exhibits restorative properties, if handled carelessly, may cause an explosion or fire.
3. Mixes well with water (H2O) in any ratio. Forms several hydrates. Concentrated solutions of this acid have a slightly oily consistency. Aqueous solutions of this acid have good stability and low oxidizing ability. With water, the substance we are considering forms an azeotropic mixture, which boils at a temperature of 203 degrees and contains 72 percent HClO4.
4. Perchloric acid (formula HClO4) is one of the Because of this, in its environment, some acidic compounds behave like bases.
5. Under conditions of reduced pressure at low heat a mixture of perchloric acid and phosphoric anhydride forms an oily, colorless liquid - perchloric anhydride:
2HClO4 (perchloric acid) + P4O10 (phosphoric anhydride) = Cl2O7 (perchloric anhydride) + H2P4O11
Methods of obtaining
1. Aqueous solutions of this substance can be obtained in two ways. The first is the electrochemical oxidation of chlorine or hydrochloric acid in concentrated hydrochloric acid, and the second - in the exchange decomposition of sodium or potassium perchlorates with inorganic strong acids.
2. Anhydrous perchloric acid can also be obtained in two ways. The first is the interaction of potassium (K) or sodium (Na) perchlorates with sulfuric acid in concentrated form, and the second is the interaction of oleum with an aqueous solution of perchloric acid:
KClO4 (aqueous solution of perchloric acid) + H2SO4 = KHSO4 (potassium hydrogen sulfate) + HClO4 (perchloric acid)
Application of perchloric acid
Concentrated solutions are widely used to obtain perchlorates (salts of this acid) and in analytical chemistry;
Perchloric acid is used in the decomposition of ores, as a catalyst, and in the analysis of minerals;
Potassium perchlorate (formula: KClO4), a salt of this acid, is used in the creation and magnesium perchlorate (anhydrone, Mg(ClO4)2) is used as a desiccant.
Safety at work
Anhydrous perchloric acid cannot be stored or transported for a long time, since under standard conditions it quickly decomposes and can subsequently spontaneously explode.
Other inorganic chlorinated acids:
1. (formula: HCl) is a monobasic, caustic liquid that fumes in air. Used in electroplating (picking, pickling) and in hydrometallurgy, for cleaning metals during tinning and soldering, for producing chlorides of manganese, zinc, iron and other metals. IN food industry this substance is registered as food additives E507.
2. Hypochlorous acid (formula: HClO) - very monobasic weak acid. Can only exist in solutions. Used for sanitary purposes, as well as for bleaching fabrics and pulp.
3. Chlorous acid(HClO2) - monobasic acid medium strength. Unstable in free form, it usually decomposes quickly in a dilute aqueous solution. The anhydride of this acid is still unknown.
4. Hypochlorous acid (HClO3) - monobasic strong acid. Not obtained in free form, as it decomposes in aqueous solutions and exists at concentrations below 30 percent. Quite stable at low temperatures.
Chlorous acid
Chlorous acid- HClO 2, a monobasic acid of medium strength. The corresponding salts are chlorites.
Properties
Chlorous acid HClO 2 in its free form is unstable; even in a dilute aqueous solution it quickly decomposes:
And also for the reaction:
Salts of chlorous acid are called chlorites, they are usually colorless and highly soluble in water. Unlike hypochlorites, chlorites exhibit pronounced oxidizing properties only in an acidic environment. Of the salts, the most widely used is sodium chlorite NaClO 2, used for bleaching fabrics and paper pulp. Sodium chlorite is obtained by the reaction:
Anhydrous NaClO 2 explodes on impact and heat; ignites on contact with organic substances, rubber, paper, etc.
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Literature
- Akhmetov N. S. “General and inorganic chemistry» M.: graduate School, 2001
- Karapetyants M. Kh., Drakin S. I. “General and inorganic chemistry” M.: Chemistry 1994
Links
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Excerpt characterizing Chlorous acid
- How? You with all your weight fell upon the unfortunate Mortier with one division, and this Mortier leaves between your hands? Where is the victory?“However, seriously speaking,” answered Prince Andrei, “we can still say without boasting that this is a little better than Ulm...
- Why didn’t you take us one, at least one marshal?
– Because not everything is done as expected, and not as regularly as at the parade. We expected, as I told you, to reach the rear by seven o'clock in the morning, but did not arrive at five in the evening.
- Why didn’t you come at seven o’clock in the morning? “You should have come at seven o’clock in the morning,” Bilibin said smiling, “you should have come at seven o’clock in the morning.”
– Why didn’t you convince Bonaparte through diplomatic means that it was better for him to leave Genoa? – Prince Andrei said in the same tone.
“I know,” Bilibin interrupted, “you think it’s very easy to take marshals while sitting on the sofa in front of the fireplace.” This is true, but still, why didn’t you take him? And do not be surprised that not only the Minister of War, but also the August Emperor and King Franz will not be very happy with your victory; and I, the unfortunate secretary of the Russian embassy, do not feel any need to give my Franz a thaler as a sign of joy and let him go with his Liebchen [sweetheart] to the Prater... True, there is no Prater here.
He looked straight at Prince Andrei and suddenly pulled the collected skin off his forehead.
“Now it’s my turn to ask you why, my dear,” said Bolkonsky. “I confess to you that I don’t understand, maybe there are diplomatic subtleties here that are beyond my weak mind, but I don’t understand: Mack is losing an entire army, Archduke Ferdinand and Archduke Charles do not show any signs of life and make mistakes after mistakes, finally, alone Kutuzov wins a real victory, destroys the charme [charm] of the French, and the Minister of War is not even interested in knowing the details.
“That’s exactly why, my dear.” Voyez vous, mon cher: [You see, my dear:] hurray! for the Tsar, for Rus', for the faith! Tout ca est bel et bon, [all this is fine and good,] but what do we, I say, the Austrian court, care about your victories? Bring us your good news about the victory of Archduke Charles or Ferdinand - un archiduc vaut l "autre, [one Archduke is worth another,] as you know - even over a company of Bonaparte’s fire brigade, that’s another matter, we’ll thunder into the cannons. Otherwise this , as if on purpose, can only tease us. Archduke Charles does nothing, Archduke Ferdinand is covered in shame, you abandon Vienna, you no longer defend, comme si vous nous disiez: [as if you told us:] God is with us, and God is with us. you, with your capital. One general, whom we all loved, Shmit: you bring him under the bullet and congratulate us on the victory!... Agree that it is impossible to think of anything more irritating than the news that you bring C "est comme un fait expres, Comme un fait expres. [This is as if on purpose, as if on purpose.] Besides, well, if you had definitely won a brilliant victory, even if Archduke Charles had won, what would it have changed in general progress business? It is too late now that Vienna is occupied by French troops.
With the release of hydrogen, it interacts with metal oxides and.
Concentrated hydrochloric acid contains 37% HCl and has a density of 1.19 g/cm3. It has a pungent odor and “smoke” in air due to the release of hydrogen chloride gas. Technical acid has yellow, which is caused by the admixture mainly of iron salts.
1. History of discovery
It is difficult to say who and when first received hydrochloric acid. It is known that already at the end of the 15th century. alchemist Vasily Valentin and in the 16th century. Andreas Libavius, in an executive search for a miraculous vital elixir, calcined table salt with galloon and vitriol in their alchemical instruments and obtained a product that was described as “sour alcohol.” This was the hydrochloric acid we now knew, very unclean.
For the first researchers, it was a completely new substance, with properties that greatly amazed their imagination. Sniffing it, they choked and coughed, “sour alcohol” fumes in the air. When tasted, it burned the tongue and palate, it corroded metals and destroyed tissues.
In 1658, the German chemist I.R. Glauber (1604-1670) found new way obtaining hydrochloric acid, which he called "hydrochloric alcohol". This method is still widely used in laboratories. He heated table salt with concentrated sulfuric acid and the “smoke” that was released was absorbed by water.
In 1772, the English chemist Joseph Priestley (1733-1804) found that the action of sulfuric acid on table salt releases a colorless gas that can be collected over mercury, and this gas has an extremely high ability to dissolve in water. An aqueous solution of this gas was called “hydrochloric acid” (acidum muriaticum), and Priestley called the gas itself “pure gaseous hydrochloric acid.”
In 1774, the Swedish chemist K.V. Scheele (1742-1786), studying the effect of hydrochloric acid (which he also called “hydrochloric alcohol”) on manganese (IV) oxide, found that it dissolves in hydrochloric acid in the cold, forming a dark brown solution, from which, when heated, a yellow-green gas is released, which has a very pungent odor and the ability to destroy vegetable paints and acts on all metals, not excluding gold. Scheele, as a follower of the phlogiston theory that was dominant at that time, believed that the meaning of this reaction was that under the influence of manganese (IV) oxide with hydrochloric acid, phlogiston leaves it, due to which hydrochloric acid turns into a yellow-green gas. Therefore, he called the gas itself “dephlogisticated with hydrochloric acid.”
2. Typical reactions
3. Chemical properties
Sources
- F. A. Derkach "Chemistry" L. 1968
| Basic chlorine-containing inorganic acids | |
|---|---|
| Chloride acid (HCl) ? Hypochloric acid (HClO) ? |
Strong oxidizing agent
Among the huge variety of chemical reagents, acids occupy special place. The importance of their use depends on physical and chemical properties. Depending on the degree of oxidation, they are divided into harmless, such as ascorbic, aminoacetic, and citric acid, which can be bought without a prescription in a regular pharmacy, and dangerous, such as hydrofluoric, sulfuric or perchloric. These acids, unlike the first ones, are sold in specialized pharmacies or stores, one of which is the Moscow retail chemical reagents store "Prime Chemicals Group".
Concept
Perchloric acid is a monobasic anhydrous acid, one of the most powerful, dangerous and common chemicals. The substance contains chlorine with to a large extent oxidation, which makes it the strongest oxidizing agent. Acid salts are also used as an oxidizing agent. In its structure, perchloric acid is a colorless volatile liquid; hygroscopic. Upon contact with air, the chemical absorbs water and begins to smoke (forms monohydrate), gradually darkens and spontaneously explodes. An aqueous solution of perchloric acid has an oily consistency and has a lower oxidizing ability and is highly flammable.
Properties of perchloric acid:
Smokes heavily on contact with air;
- unstable;
- highly soluble in organofluorine and chlorine solvents, ethanol;
- miscibility with water in any ratio;
- capable of dissolving gold, platinum group metals, silver, etc.; does not interact with bromine;
- upon contact with alcohol, paper and charcoal, an explosion occurs.
Receipt
An aqueous solution of this reagent is obtained by electrochemical oxidation of hydrochloric acid or chlorine contained in perchloric acid in high concentration, using special laboratory glassware. An anhydrous chemical reagent is obtained by reacting potassium or sodium perchlorate with a concentrated solution of sulfuric acid. The substance was first obtained using this method at the beginning of the 19th century. It is obtained in the same way today.
Application
The main areas of application of this acid: 
- analytical chemistry(production of perchlorates);
- mining industry (catalyst for the decomposition of ores, as well as for the study of minerals);
- chemical industry(during production explosives and dehumidifiers).
Precautions and operating rules
When working with perchloric acid, as with other aggressive chemicals, the strictest precautions must be observed. To avoid direct contact with the substance, all research, experiments or other forms of work should be carried out in:
- respirators and gas mask (to protect respiratory tract);
- safety glasses;
- nitrile gloves;
- special clothing (apron, shoe covers) and other rubber products.
During transportation and storage, the following recommendations should be adhered to: anhydrous acid has a short shelf life, so it cannot be stored for a long time, since it is unstable and quickly decomposes under normal conditions. This may lead to a spontaneous explosion. Store away from other acids and metals with which it may react. There should be no heat sources in the storage room. It should be protected from sunlight.
Danger to the body
Many acids have a positive effect on the body. They participate in metabolic processes, and their deficiency can cause serious disorders, which cannot be said about this acid. Even with the slightest contact, it causes chemical burns and affects the skin and mucous membranes.
Where to buy chemical reagents with a quality guarantee?
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