Physical properties of nitrogen acid. Nitrogen and nitric acids and their salts

Hno. 2 It has a weak. Very unstable, can only be in diluted solutions:

2 Hno. 2 No. + No. 2 + H. 2 O..

Nitrous acid salts are called nitriteor nitrogenous. Nitrites are much more stable than HNO 2.All of them are toxic.

2hno 2 + 2hi \u003d i 2 + 2no + 2H 2 O,

HNO 2 + H 2 O 2 \u003d HNO 3 + H 2 O,

5Kno 2 + 2kmno 4 + 3H 2 SO 4 \u003d 5KNO 3 + K 2 SO 4 + 2MNSO 4 + 3H 2 O.

The structure of nitrogenic acid.

In the gas phase, the planar molecule of nitrogenous acid exists in the form of two configurations of cis and trans-:

At room temperature, a trans isomer prevails: this structure is more stable. So, for cis - HNO 2.(d) DG ° F. \u003d -42,59 kJ / mol, and for trans HNO 2.(d) DG. \u003d -44.65 kJ / mol.

Chemical properties of nitrogen acid.

In aqueous solutions there is an equilibrium:

Heating, a solution of nitrogen acid decays with highlighting No. and the formation of nitric acid:

HNO 2. in aqueous solutions dissociates ( K D.\u003d 4.6 · 10 -4), slightly stronger acetic acid. Easily displaces stronger salts with stronger acids:

Azobic acid Shows oxidative and rehabilitation properties. With the action of stronger oxidants (hydrogen peroxide, chlorine, potassium permanganate) oxidation occurs in nitric acid:

In addition, it can oxidize substances that possess restorative properties:

Obtaining nitrogenous acid.

Azotic acid is obtained by dissolving nitrogen oxide (III) N 2 O 3 in water:

In addition, it is formed when dissolved in nitrogen oxide (IV) NO 2.:

.

The use of nitrogen acid.

Azobic acid is used to diazotize primary aromatic amines and formation of diazonium salts. Nitrites are used in organic synthesis in the production of organic dyes.

Physiological effect of nitrate acid.

Nitrogenic acid is toxic and has a pronounced mutagenic effect, as it is a deaminting agent.

Azobic acid

If you heat up potassium or sodium nitrate, then they lose part of the oxygen and pass into the nitrogenous acid HNO2 salts. The decomposition is lightering in the presence of lead bonding the released oxygen:

Nitrous acid salts - nitrites - Form crystals well soluble in water (with the exception of silver nitrite). Nitrite sodium Nano 2 is used in the production of various dyes.

Under action on a solution of some nitrite diluted with sulfuric acid, free nitrate acid is obtained:

It belongs to the number of weak acids (K \u003d A-10 ~ 4) and is known only in highly diluted aqueous solutions. When the solution is concentrated or, during its heating, nitrogenous acid disintegrates:

The degree of oxidation of nitrogen in nitrogenous acid is +3, i.e. It is an intermediate between the lowest and highest possible values \u200b\u200bof the degree of nitrogen oxidation. Therefore, HNO 2 shows a redox duality. Under the action of reducing agents, it is restored (usually to NO), and in reactions with oxidizing agents - oxidized to HNO 3. Examples include the following reactions:

Nitric acid

Pure nitric acid HNO3 is a colorless liquid with a density of 1.51 g / cm3, at -42 0C frozen into a transparent crystalline mass. In the air, it, like concentrated hydrochloric acid, "smokes", as the pairs form small droplets of fog with moisture.

Nitric acid does not differ in strength. Already under the influence of light, it gradually decomposes:

The higher the temperature and the concentrate acid, the faster there is decomposition. The released nitrogen dioxide is dissolved in acid and gives it a brown color.

Nitric acid belongs to the number of strongest acids; In dilute solutions, it completely disintegrates on H + and NO 3 ions.

Characteristic property Nitric acid is its pronounced oxidative ability. Nitric acid is one of the most energetic oxidants. Many non-metals are easily oxidized by it, turning into appropriate acids. So, the sulfur when boiling with nitric acid is gradually oxidized in sulfuric acid, phosphorus - in phosphoric. The smoldering corner, immersed in concentrated HNO 3, flared brightly.

Nitric acid is valid for almost all metals (with the exception of gold, platinum, tantalum, rhodium, iridium), turning them into nitrates, and some metals are in oxides.

Concentrated HNO 3 passivates some metals. Another Lomonosov discovered that iron, easily dissolved in dilute nitric acid, does not dissolve in cold concentrated HNO 3. It was later established that a similar effect of nitric acid has on chromium and aluminum. These metals are transferred under the action of concentrated nitric acid into a passive state (see § 100).

The degree of nitrogen oxidation in nitric acid is +5. Speaking as an oxidizing agent, HNO 3 can be recovered to various products:

Which of these substances is formed, i.e. how deeply the nitric acid is restored in one case, depends on the nature of the reducing agent and on the reaction conditions, primarily on the concentration of the acid. The higher the HNO 3 concentration, the less deeply it is restored. In reactions with concentrated acid, NO 2 is most often allocated. In the interaction of dilute nitric acid with low-active metals, for example, NO is allocated. In the case of more active metals - iron, zinc - n 2 o. Highly diluted nitric acid reacts with active metals - zinc, magnesium, aluminum - with the formation of ammonium ion, giving ammonium nitrate. Usually several products are usually formed.

To illustrate the scheme of reactions of oxidation of certain metals with nitric acid:

Under the action of nitric acid to metals, hydrogen, as a rule, is not allocated.

In the oxidation of non-metals, concentrated nitric acid, as in the case of metals, is restored to NO 2, for example:

More diluted acid is usually restored to NO, for example:

The following schemes illustrate the most typical cases of the interaction of nitric acid with metals and non-metals. In general, redox reactions going with the participation of HNO 3 are difficult.

A mixture consisting of 1 volume of nitric and 3-4 volumes concentrated of hydrochloric acid, called royal vodka. The royal vodka dissolves some metals that do not interact with nitric acid, including the "king of metals" - gold. Its effect is explained by the fact that nitric acid oxidizes salt with the release of free chlorine and formation nitroxide nitrogen (Iii), or chloride nitrosil NOCL:

Nitrosil chloride is an intermediate reaction product and decomposes:

Chlorine at the time of isolation consists of atoms, which causes the high oxidative capacity of royal vodka. The oxidation reactions of gold and platinum proceed mainly according to the following equations:

With an excess of hydrochloric acid, gold chloride (III) and platinum chloride (IV) form complex compounds H [AIS1 4] and H 2.

On many organic substances Nitric acid acts so that one or more hydrogen atoms in the organic compound molecule are replaced by nitro groups - NO 2. This process is called nutrovania and has great importance in organic chemistry.

The electronic structure of the HNO 3 molecule is considered in § 44.

Nitric acid is one of the most important nitrogen compounds: in large quantities it is consumed in the production of nitrogen fertilizers, explosives and organic dyes, serves as an oxidizing agent in many chemical processes, is used in the production of sulfuric acid according to the nitrous method, it is used for the manufacture of cellulose varnishes, film.

Nitric acid salts are called nitrates. All of them are well dissolved in water, and when heated is decomposed with the release of oxygen. At the same time, nitrates of the most active metals go to nitrites:

Nitrates of most of the remaining metals during heating decompose on metal oxide, oxygen and nitrogen dioxide. For example:

Finally, the nitrates of the least active metals (for example, silver, gold) decompose when heated to free metal:

Easily cleaving oxygen, nitrates at high temperatures are energetic oxidizers. Their aqueous solutions, on the contrary, almost do not show oxidative properties.

Nitrates of sodium, potassium, ammonium and calcium are most important, which are in practice are called sotitors.

Nitrate sodium Nano 3, or sodium Selitra, Sometimes called the Chilean Selutyra, is found in large quantities in nature only in Chile.

Nitrate potassium KNO 3, or potash SelitraIn small quantities, it is also found in nature, but mainly it turns out artificially in the interaction of sodium nitrate with potassium chloride.

Both of these salts are used as fertilizers, and potassium nitrate contains two element-needed plants: nitrogen and potassium. Sodium and potassium nitrates are also used in glass wool and in food Industry For canning products.

Calcium nitrate CA (NO 3) 2, or calcium Selitra, it turns out in large quantities of nitric acid neutralization with lime; Applied as fertilizer.

Ammonium nitrate NH 4 NO 3.

The student is recommended to draw up complete equations of these reactions.

Three of the five nitrogen oxides react with water, forming nitrogenous H1M0 2 and nitrogen HN0 3 acids.

Azotic acid is weak and unstable. It can only be present in a small concentration in the cooled aqueous solution. It is practically obtained by the action of sulfuric acid per solution of salt (most often Nan0 2) during cooling almost to 0 ° C. When attempting to increase the concentration of nitrogenous acid from the solution to the bottom of the vessel, a blue liquid - nitrogen oxide (W) is released. With an increase in the temperature of nitrogenous acid decomposes but reactions

Nitrogen oxide (1U) reacts with water, giving two acids (see above). But taking into account the decomposition of nitrogen acid, the total reaction N 2 0 4 with water when heated is written as follows:

Nitrous acid salts (nitrites) are sufficiently stable. Potassium or sodium nitrites can be obtained by dissolving nitrogen oxide (1U) in alkali:

The formation of a mixture of salts is quite understandable, since, reacting with water, N 2 0 4 forms two acids. Neutralization by alkali prevents the decomposition of unstable nitrogenous acid and leads to a displacement of the equilibrium of the reaction N 2 0 4 with water completely to the right.

Alkali metal nitrites are also obtained with thermal decomposition of their nitrates:

Nitrous acid salts are well soluble in water. Solubility of some nitrites is exceptionally high. For example, at 25 ° C, potassium nitrite solubility coefficient is 314, i.e. In 100 g of water, 314 g of salts dissolve. Alkali metal nitrites are thermally stable and melted without decomposition.

In the acidic nitrite medium act as rather strong oxidizers. In fact, oxidative properties exhibits the resulting weak nitrate acid. From iodide solutions, iodis is highlighted:

The iodine is detected by color, and nitrogen oxide - by characteristic odor. Nitrogen goes out SO +3 B. SO +2.

Oxidifiers are stronger than nitrate acid, oxidize nitrites to nitrates. In the acidic medium, potassium permanganate solution is discolored when the sodium nitrite is added:

Nitrogen goes out SO +3 B. SO +5. Thus, nitrate acid and nitrites show redox duality.

Nitrites of poisonous, as they are oxidized in hemoglobin iron (P) to iron (H1) and hemoglobin loses the ability to attach and transfer oxygen in the blood. The use of a large number of nitrogen fertilizers significantly accelerates the growth of plants, but they contain nitrates and nitrites at elevated concentrations. The use of thus grown vegetables and berries (watermelons, melons) leads to poisoning.

Huge practical value It has nitric acid. Its properties are combined with acid (almost complete ionization in aqueous solution), strong oxidative properties and the ability to transfer N0 2 + nitro group to other molecules. Nitric acid is used in large quantities for the production of fertilizers. In this case, it serves as a source of nitrogen required for plants. It is used to dissolve metals and obtaining well soluble salts - nitrates.

The extremely important direction of the use of nitric acid is the nitration of organic substances to obtain a variety of organic products containing nitro groups. Among organic nitro compounds there are medicinal substances, dyes, solvents, explosives. Every year, global nitric acid production exceeds 30 million tons.

In the period before the industrial development of the ammonia synthesis and its oxidation, nitric acid was obtained from nitrates, for example, from the Chilean Nan0 3 nitrate. Selitera heated with concentrated sulfuric acid:

The distinguished nitric acid pairs in the cooled receiver are condensed into a high HN0 liquid.

Currently, nitric acid is obtained according to various variants of the method, in which the source substance is nitrogen oxide (P). As follows from the consideration of nitrogen properties, its NO oxide can be obtained from nitrogen and oxygen at a temperature of more than 2000 ° C. Maintaining such high temperatures requires high energy costs. The method was technically implemented in 1905 in Norway. The heated air passed through the combustion zone of the volt arc at a temperature of 3000-3500 ° C. The gases emerging from the device contain only 2-3% nitrogen oxide (H). By 1925, world production of nitrogen fertilizers reached 42,000 tons of nitrogen fertilizers in this method. According to the modern scale of fertilizer production, it is very small. In the future, the expansion of nitric acid production went along the path of ammonia oxidation to nitrogen oxide (s).

With ordinary combustion of ammonia, nitrogen and water are formed. But when carrying out a reaction at a lower temperature using a catalyst, ammonia oxidation ends with the formation of NO. The appearance of NO when the mixture of ammonia and oxygen is passed through the platinum grid, it has long been known, but this catalyst does not give a sufficiently high oxide yield. It was possible to use this process for factory production only in the XX century, when a more efficient catalyst was found - platinum and rhodium alloy. Metal Rhodes, which has been extremely necessary in the production of nitric acid, is approximately 10 times more rare than platinum. With a PT / RH catalyst in a mixture of ammonia and oxygen of a certain composition at 750 ° C reaction

gives an output NO to 98%. This process is thermodynamically less profitable than the combustion of ammonia to nitrogen and water (see above), but the catalyst provides a rapid compound of nitrogen atoms remaining after the hydrogen loss of the ammonia molecule, with oxygen preventing the formation of N 2 molecules.

When cooled a mixture containing nitrogen oxide (P) and oxygen, nitrogen oxide (1U) N0 2 is formed. Next variants of the transformation N0 2 apply in nitric acid. Diluted nitric acid is obtained by dissolving NQ 2 in water at elevated temperature. The reaction is given above (p. 75). Nitric acid with a mass fraction of up to 98% is obtained by reaction in a mixture of liquid N 2 0 4 with water in the presence of gaseous oxygen under greater pressure. Under these conditions, formed simultaneously with nitric acid, nitrogen oxide (P) has time to oxide with oxygen to N0 2, which immediately reacts with water. The following total response is obtained:

The entire chain of consecutive reactions of the conversion of atmospheric nitrogen into nitric acid can be represented as:

The reaction of nitrogen oxide (1U) with water and oxygen is pretty slow, and it is practically unable to achieve its complete transformation into nitric acid. Therefore, in plants producing nitric acid, nitrogen oxides will always be released into the atmosphere. From the factory pipe goes reddish smoke - "Fox Tail". The color of the smoke is due to the presence of N0 2. In a significant space around a large plant from nitrogen oxides, forests die. Especially sensitive to the effects of N0 2 coniferous species of trees.

Anhydrous nitric acid is a colorless liquid with a density of 1.5 g / cm 3, boiling at 83 ° C and freezing at -41, b ° C into a transparent crystalline substance. On the air, nitric acid is similar to concentrated hydrochloric acid, since the acid pairs form with water steam air of the fog droplets. Therefore, nitric acid with a small content of water is called smoking. It, as a rule, has a yellow color, as under the action of light decomposes with the formation of N0 2. Smoking acid is applied relatively rarely.

Usually nitric acid is produced by the industry in the form of an aqueous solution with a mass fraction of 65-68%. Such a solution is called concentrated nitric acid. Solutions with a mass fraction of HN0 3 less than 10% - diluted nitric acid. Solution with a mass fraction of 68.4% (density of 1.41 g / cm 3) is azeotropic mixtureBoiling at 122 ° C. The azeotropic mixture is characterized by the same composition of both liquid and steam above it. Therefore, distillation of the azeotropic mixture does not lead to a change in its composition. In concentrated acid, along with conventional Hn0 3 molecules, there are smallssociation of orthoso-acidic acid molecules H 3 N0 4.

Concentrated nitric acid passivates The surface of some metals, such as iron, aluminum, chromium. When contacting these metals with concentrated HN () 3 chemical reaction Does not go. This means that they cease to react with acid. Nitric acid can be transported in steel tanks.

Both smoking and concentrated nitric acid is a strong oxidizing agent. Glowing coal flashes when contact with nitric acid. Skipidar drops, falling into nitric acid, flames, forming a large flame (Fig. 20.3). Concentrated acid oxidizes when heated sulfur and phosphorus.

Fig. 20.3.

Nitric acid in a mixture with concentrated sulfuric acid manifests basic properties. From the HN0 molecule 3 Hydroxide ion is cleaved, and the nitrole (nitronium) ion is formed:

The equilibrium concentration of nitronium is small, but such a mixture thirs organic substances with the participation of this ion. Of this example It follows that, depending on the nature of the solvent, the behavior of the substance can be radically changed. In water hn0 3 Shows the properties of strong acid, and in sulfuric acid turns out to be the basis.

In dilute aqueous solutions, nitric acid is almost completely ionized.

In concentrated solutions of nitric acid, HN0 3 molecules are used as an oxidizing agent, and in diluted - ions N0 3 with the support of the acidic medium. Therefore, nitrogen depending on the concentration of acid and the nature of the metal is restored to different products. In a neutral medium, i.e., in the salts of nitric acid, ion N0 3 becomes a weak oxidizing agent, but with the addition of severe acid to neutral solutions of nitrates, the latter act as nitric acid. According to the power of oxidative properties in the acidic medium ion N0 3 stronger than H +. Hence the following important consequence.

Under the action of nitric acid to metals, instead of hydrogen, various nitrogen oxides are distinguished, and in reactions with active metals, nitrogen is restored to an NH * ion.

Consider the most important examples of reactions of metals with nitric acid. Copper in the reaction with dilute acid restores nitrogen to NO (see above), and in reaction with concentrated acid - to N0 2:

Iron is passivated by concentrated nitric acid, and an acid of average concentration is oxidized to the degree of oxidation +3:

Aluminum reacts with a strongly diluted nitric acid without gas selection, since nitrogen is restored to SO -3, forming an ammonium salt:

Nitric acid salts, or nitrates, are known for all metals. Often the old name of some nitrates is applied - selitra(Sodium Seliver, Potash Selith). This is the only family of salts in which all salts are soluble in water. Ion n0 3 is not painted. Therefore, nitrates or are colorless salts, or have a color of the cation that is part of them. Most nitrates are allocated from aqueous solutions in the form of crystallohydrates. Anhydrous nitrates are NH 4 N0. 3and alkali metal nitrates except LIN0 3 * 3h. 2 0.

Nitrates are often used to conduct exchange reactions in solutions. Alkali metal nitrates, calcium and ammonium in large quantities are used as fertilizers. For several centuries, potassium nitrate was of great importance in military affairs, as it was a component of the only explosive - powder. It was obtained mainly from the urine of horses. The nitrogen contained in the urine with the participation of bacteria in special saltryproynye piles passed to nitrates. When the resulting fluid is evaporated, first of all crystallized potassium nitrate. This

an example shows how limited by the sources of nitrogen compounds before the development of the ammonia synthesis industry.

The thermal decomposition of nitrates occurs at temperatures below 500 ° C. When heated nitrates of active metals, they turn into nitrites with oxygen release (see above). Nitrates of less active metals with thermal decomposition give metal oxide, nitrogen oxide (1 Y) and oxygen:

Nitrous and nitric acid salts

Nitrogen fertilizers

Grade 9.

Type of lesson - study of a new material.

View of the lesson - Conversation.

Objectives and lesson tasks.

Educational. To introduce students with the methods of obtaining, properties and applications of nitrates and nitrites. Consider the problem of high nitrate content in agricultural products. Give an idea of \u200b\u200bnitrogen fertilizers, their classification and representatives.

Developing. Continue the development of skills: allocate the main thing, to establish causal relationships, to conduct an abstract, to conduct an experiment, apply knowledge in practice.

Educational. Continue the formation of scientific worldview, upbringing a positive attitude to knowledge.

Methods and methodological techniques. Independent work Pupils with research and popular literature, preparation of messages, the performance of laboratory experiments and a demonstration experiment, the dialogic method of presenting knowledge with the elements of the study, the current knowledge control using the test.

The structure of the lesson.

Announcement themes, goals.

Message of homework and comment to it.

The presentation of a new material (heuristicBested with a support for the experiment).

Current control Knowledge using the test.

Summing up the lesson.

Equipment and reagents.Safety poster; Tables "Decomposition of nitrates when heated", "Classification of nitrogen fertilizers", "Claimed row of acids"; Test "Nitrogen and its connections" (two options); Cards with task conditions.

For demonstration experiment: demonstration tripod for test tubes, alcohol, match, holder for test tubes, crucible tongs, iron spoon for burning substances, beaches, iron leaf for burning black powder, large tubes, cotton wool impregnated with concentrated alkali solution, cup with sand, three laboratory tripod; Concentrated solutions of sodium hydroxide and sulfuric acid, crystalline salts - potassium nitrate, copper nitrate (II), silver nitrate; woodcore, copper plate, sulfur, diphenylamine solution in concentrated sulfuric acid (dark flask, 0.1 g of diphenylamine on
10 ml of H 2 SO 4 (conc.); Solutions of potassium iodide, diluted sulfuric acid, potassium nitrite; in demonstration test tubes - vegetable juices cabbage, zucchini, pumpkins; Yodcrachmal paper.

For laboratory experiments: Test tube with two zinc granules, three empty tubes, glass sticks, two test tubes with crystal nitrates (pea volume) - barium nitrate and aluminum nitrate, lactium, copper nitrate solutions (II), silver nitrate, hydrochloric acid, barium chloride, distilled water .

Epigraph. "No science needs an experiment to such an extent as chemistry" (Michael Faraday).

DURING THE CLASSES

Safety Information

All nitrates relate to the freezing substances. Store nitrates are necessary separately from organic and inorganic substances. All experiments with the formation of nitrogen oxide (IV) must be carried out in large tubes, closed with cotton swab, moistened with concentrated alkali solution. Nitric acid should be stored in dark flasks, take care of fire. Especially toxic nitrite.

Homework

Tutorial O.S. Gabrielevina "Chemistry-9", § 26, UPR. 7. Strong students receive individual tasks.

Individual tasks

1. Translate such an entry from the alchemical language: "" Strong vodka "devours" Moon ", releasing" fox tail ". The thickening of the resulting liquid generates "hellish stone", which is ink fabric, paper and hands. So that the "moon" rose again, calcinate the "hellish stone" in the furnace. "

Answer.

"Hell stone" - silver nitrate - when heated is decomposed with the formation of silver - "Moon rose":

2Agno 3 (cr.) 2Ag + 2NO 2 + O 2.

2. In one old scientific treatise, the experience of obtaining a "red precipitate" *: "Mercury is dissolved in nitric acid, the solution is evaporated and the residue is heated until it is made" red "." What is a "red precipitate"? Write the equations of reactions leading to its formation, considering that mercury in the resulting compounds has the degree of oxidation +2 and that, under the action of nitric acid, gas is released on mercury.

Answer. Equations reactions:

Mercury oxide (II) HGO. depending on the method of obtaining is red or yellow (HG 2 O - black color). In the air, mercury is not oxidized at room temperature. With long-term heating, mercury is combined with air oxygen, forming a red mercury oxide (II) - NGO, Which with stronger heating again decomposes on mercury and oxygen:

2NGO \u003d 2NG + O 2.

Studying a new material

Composition and nomenclature of nitric acid salts

Teacher. What do the Latin name "nitrogenium" and the Greek "nitrate" mean?

Student. "Nitrogenium" means "referring to Selitra", and "nitrate" means "Selith".

Teacher. Nitrates of potassium, sodium, calcium and ammonium are called Selitors. For example, Selitras:KNO 3 - nitrate potassium (Indian Selith), NAno 3 - sodium Nitrate (Chilean Seliver), CA (NO 3) 2 - calcium nitrate (Norwegian Selith), NH 4 NO 3 - ammonium nitrate (ammonium or ammonium nitrate, no fields in nature). The German industry is considered the first in the world who received salt NH 4 NO 3 from nitrogen N 2. air and hydrogen water suitable for plant nutrition.

Physical properties of nitrates

Teacher. About what relationship exists between the structure of the substance and its properties, we will learn from laboratory experience.

Physical properties of nitrates

The task. Two test tubes contain crystalline nitrates: VA (NO 3) 2 and Al (NO 3) 3. In each tube, pour 2 ml of distilled water, mix the glass wand. Observe the process of dissolving salts. Solutions Store to the nature of the environment.

Teacher. What is called salts?

Student. Salts are complex substances consisting of metal ions and acid residual ions.

Teacher. Need to build a logical chain: View chemical bond - The type of crystal lattice - the strength of the interaction between particles in the nodes of the lattice - the physical properties of substances.

Student. Nitrates relate to salts, so they are characterized by ionic communication and an ionic crystal lattice in which ions are held by electrostatic forces. Nitrates - solid crystalline substances, refractors, soluble in water, strong electrolytes.

Obtaining nitrates and nitrites

Teacher. Name ten ways to produce salts based on the chemical properties of the most important classes of inorganic compounds.

Student.

1) Metal + non-metall \u003d salt;

2) metal + acid \u003d salt + hydrogen;

3) metal oxide + acid \u003d salt + water;

4) metal hydroxide + acid \u003d salt + water;

5) metal hydroxide + acid oxide \u003d salt + water;

6) metal oxide + non-metal oxide \u003d salt;

7) Salt 1 + metal hydroxide (alkali) \u003d salt 2 + metal hydroxide (insoluble base);

8) Salt 1 + acid (severe) \u003d salt 2 + acid (weak);

10) Salt 1 + Metal (Active) \u003d Salt 2 + Metal (less active).

Specific methods for obtaining salts:

12) Salt 1 + non-metall (active) \u003d salt 2 + non-metal (less active);

13) amphoter metal + spin \u003d salt + hydrogen;

14) non-metall + alkali \u003d salt + hydrogen.

Specific method of obtaining nitrates and nitrites:

nitrogen oxide (IV) + spin \u003d Sol1 + Sol2 + water, for example (writes on the board):

This is a redox reaction, its type is dumitation, or disproportionation.

In the presence of oxygen from NO 2 andNaoh. It turns out not two salts, but one:

The type of redox reaction is intermolecular.

Teacher. Why are the experiments with the formation of nitrogen oxide (IV) should be carried out in large tubes, closed with cotton swab, moistened with water alkali?

Student. Nitrogen oxide (IV) is a poisonous gas, it interacts with alkali and neutralizes.

Chemical properties of nitrates

Students perform laboratory experiments along the printed technique.

Properties of nitrates common with other salts

Interaction of nitrates with metals,
acids, alkalis, salts

The task. Note the signs of each reaction, write molecular and ionic equations corresponding to the schemes:

CU (NO 3) 2 + Zn ...

AGNO 3 + HCL ...

CU (NO 3) 2 + NaOH ...

AGNO 3 + BACL 2 ...

Hydrolysis nitrates

The task. Determine the reaction of the proposed saline solutions: VA (NO 3) 2 and Al (NO 3) 3. Write molecular and ionic equations possible reactions With an indication of the solution environment.

Specific properties of nitrates and nitrites

Teacher. All nitrates are thermally unstable. When heatedthey are decomposewith the formation of oxygen. The nature of other reaction products depends on the position of the metal forming the nitrate, in the electrochemical row of stresses:

Special position occupies ammonium nitrate, decomposing without a solid residue:

NH 4 NO 3 (cr.) N 2 O + 2H 2 O.

The teacher makes demonstration experiences.

Experience 1. Depaction of the Nitrate of Potassium. In a large test tube, placing 2-3 g of potassium crystalline nitrate, heat before moltening the salt. In the melt throw a wooden corner preheated in an iron span. Students observe a bright outbreak and coal burning. Under the tube it is necessary to substitute a cup with sand.

Teacher. Why is the corner, lowered to the molten potash salter, burns instantly?

Student. The nitrate decomposes with the formation of oxygen gas, so the preheated corner is instantly burns in it:

C + O 2 \u003d CO 2.

Experience 2. Depaction of copper nitrate (II). In a large tube, placing the crystalline nitrate of copper (II) (volume with a pea), a test tube to close with a cotton swab, moistened with concentrated alkali solution. Secure the test tube in the tripod horizontally and heat.

Teacher. Pay attention to the signs of reaction.

Students observe the formation of brown gas NO 2 and black copper oxide (II) Cuo.

The student at the board is the reaction equation:

The type of redox reaction is intramolecular.

Experience 3. Depaction of silver nitrate. Ecruce in a tube closed with a cotton swab, moistened with concentrated alkali solution, several crystals of silver nitrate.

Teacher. What gases are distinguished? What remains in the test tube?

The student at the board responds to questions, constitutes the reaction equation:

The type of redox reaction is intramolecular. The test tube remains a solid residue - silver.

Teacher. Quality reaction to nitrate ion NO 3 - - interaction of nitrates with metallic copper when heated in the presence of concentrated sulfuric acid or with diphenylamine solution in H 2 SO 4 (conc.).

Experience 4. Quality reaction to ion NO 3 -. In a large dry tube, placing a cleaned copper plate, several potassium nitrate crystals, pour a few drops of concentrated sulfuric acid. The tube is closed with a cotton swab, moistened with a concentrated alkali solution and heat.

Teacher. Name signs of reaction.

Student. Brown nitrogen oxide (IV) appear in the tube, which is better to observe on the white screen, and on the border copper - the reaction mixture appears green and copper nitrate crystals (II).

Teacher (Demonstrates a scheme for reducing relative acids of acids). In correspondence with a number of acids, each previous acid can displace the subsequent salt from salt.

The student at the board is the reaction equations:

KNO 3 (cr.) + H 2 SO 4 (conc.) \u003d KNSO 4 + NNO 3,

The type of redox reaction is intermolecular.

Teacher. Second high-quality reaction to nitrate ionNO 3 - Let's spend a little later, when studying the content of nitrates in food.

Quality reaction to nitrite ion NO 2 - - interaction of nitrites with a solution of potassium iodideKi acidified with dilute sulfuric acid.

Experience 5. Quality reaction to ion NO 2 -. Take 2-3 drops of potassium iodide solution, acidified with dilute sulfuric acid, and pour a few drops of potassium nitrite solution. Nitrites in an acidic medium are able to oxidize iodide ion I - to the free I 2, which is found in the iodochermal paper moistened in distilled water.

Teacher. How should Iodkrakhmalny paper under the action of freeI 2?

Student. Simple substanceI 2. Detected by the formation of starch.

The teacher is the reaction equation:

Teacher. In this reactionNO 2 - is an oxidizing agent. However, there are other high-quality reactions to ionNO 2 - in which he is a reducing agent. From here we can conclude that ion NO 3 - exhibits only oxidizing properties, and ion NO 2 - - both oxidative and rehabilitation properties.

Application of nitrates and nitrites

Teacher (Specifies a problematic question). Why nitrogen in nature a lot (it is part of the atmosphere), and plants often give a bad harvest due to nitrogen fasting?

Student. Plants cannot absorb molecular nitrogenN 2. From the air. This is the problem of "associated nitrogen". With a lack of nitrogen, chlorophyll is delayed, so the plants have a pale green color, as a result, the growth and development of the plant is delayed. Nitrogen is a vital element. No protein no life, but no nitrogen no protein.

Teacher. Name Methods for assimilation of atmospheric nitrogen.

Student. Part of the associated nitrogen enters the soil during thunderstorms. The chemistry of the process is as follows:

Teacher. What plants are able to increase soil fertility and what is their feature?

Student. These plants (Lupine, Lucerne, Clover, Pea, Vika) refer to the bean family (moths), on the roots of which nodule bacteria develop, capable of binding atmospheric nitrogen, translating it in compounds available for plants.

Teacher. Having removed yields, a person takes a huge amount of associated nitrogen together with them. This decline he covers not only organic, but also mineral fertilizers (nitrate, ammonium, ammonium). Nitrogen fertilizers contribute under all cultures. Nitrogen is absorbed by plants in the form of an ammonium cation and nitrate anion NO 3 -.

The teacher will demonstrate the scheme "Classification of nitrogen fertilizers".

Scheme

Teacher. One of the important characteristics is the maintenance of the nutrient element in the fertilizer. The calculation of the nutrient element for nitrogen fertilizers is carried out by nitrogen content.

Plants connecting atmospheric nitrogen

A task. What is the mass fraction of nitrogen in liquid ammonia and ammonia nitrate?

Ammonia formula - NH 3.

Mass fraction of nitrogen in ammonia:

(N) \u003d A R.(N) / M R.(NH 3) 100%,

(N) \u003d 14/17 100% \u003d 82%.

Ammonium nitrate formula - NH 4 NO 3.

Mass fraction of nitrogen in ammonia nitrate:

(N) \u003d 2 A R.(N) / M R.(NH 4 NO 3) 100%,

The effect of nitrates on the environment and human body

1st student. Nitrogen as the main nutrient element affects the growth of vegetative organs - green stems and leaves. Nitrogen fertilizers are not recommended to bring in late autumn or early spring, since the mold waters wash off to half fertilizers. It is important to comply with the rules and deadlines for making fertilizers, to make them not immediately, but in several techniques. Use slowly active forms of fertilizers (granules coated with protective film), when landing, use varieties prone to low accumulation of nitrates. The coefficient of use of nitrogen fertilizers is 40-60%. The excessive use of nitrogen fertilizers not only leads to the accumulation of nitrates in plants, but also leads to contamination by them of water bodies and groundwater. Anthropogenic sources of pollution of water bodies nitrates are also metallurgy, chemical, including pulp and paper and food industries. One of the signs of pollution of water bodies is the "flowering" of water caused by the stormy reproduction of the syneselen algae. It is especially intense, it occurs during the melting of snow, summer and autumn rains. The maximum permissible concentration (MPC) of nitrates is governed by GOST. For the sum of nitrate ions in the soil, a value of 130 mg / kg is adopted, in water of different water sources - 45 mg / l.(Pupils are recorded in the notebook: MPC (NO 3 - in the soil) - 130 mg / kg, PDC (NO 3 - in water) - 45 mg / l.)

For the plants themselves, nitrates are harmless, but for humans and herbivores they are dangerous. Mortal dose of nitrates for man - 8-15 g, permissible daily consumption - 5 mg / kg. Many plants are able to accumulate large amounts of nitrates, for example: cabbage, zucchini, parsley, dill, dining room, pumpkin, etc.

Such plants are called nithertonactors. In the human body, 70% of nitrates come with vegetables, 20% - with water, 6% - with meat and fish. Finding into the human body, part of nitrates is absorbed in the gastrointestinal tract unchanged, the other part, depending on the presence of microorganisms, pH values \u200b\u200band other factors, can turn into more poisonous nitrites, ammonia, hydroxylamineNN 2 ON ; In the intestine from nitrates can form secondary nitrosaminesR 2 n-n \u003d o Holding high mutagenic and carcinogenic activity. Signs of small poisoning are weakness, dizziness, nausea, stomach disorder, etc. reduced performance, the loss of consciousness is possible.

In the human body, nitrates interact with hemoglobin blood, turning it into methemoglobin, in which iron oxidized to Fe 3+ and can not serve as an oxygen carrier. That is why one of the signs of acute poisoning nitrates is the sinusiness of the skin. The direct relationship was revealed between cases of the appearance of malignant tumors and the intensity of entering the organism of nitrates during an excess of them in the soil.

Experience. Study of the content of nitrates in food
(High-quality reaction to nitrate ion NO 3 -)

In three large demonstration test tubes, put in 10 ml of vegetable juice cabbage, zucchini, pumpkins (on a white background). In each test tube, pour several drops of diphenylamine solutions in concentrated sulfuric acid.

The blue color of the solution will indicate the presence of nitrate ions:

NO 3 - + diphenylamine substance intense blue.

The blue color was present only in the plant juice of the zucchini, and the color was unanswed-blue. Consequently, the content of nitrates in the zucchka is insignificant, and in the cabbage with a pumpkin - and is less.

First aid for nitrate poisoning

2nd student.First aid for poisoning nitrates is an abundant washing of the stomach, receiving activated carbon, salt laxatives - glauble saltsNa 2 SO 4 10h 2 O and English salts (bitter salt) MgSO 4 7h 2 O , turning air.

Reduce the harmful effect of nitrates on the human body using ascorbic acid (vitamin C); If its ratio with nitrates is 2: 1, then nitrosomins are not formed. It is proved that first of all vitamin C, as well as vitamins E and A are inhibitors - substances that prevent and braking the processes of transformation of nitrates and nitrites in the human body. It is necessary to introduce more black and red currant, other berries and fruits into the diet of the fetus (by the way, there are practically no nitrate in the hanging fruits). And another natural nitrate neutralizer in the human body is green tea.

Causes of nitrate accumulation in vegetables
and methods of growing environmentally friendly
crop production

3rd student. The most intense nitrogen is absorbed during the growth and development of stalks and leaves. In the ripening of seeds, the consumption of nitrogen from the soil is almost terminated. The fruits who have achieved complete maturity no longer contain nitrates - there is a complete transformation of nitrogen compounds in proteins. But many vegetables appreciate precisely immature fruit (cucumbers, zucchini). Fertilizing such cultures with nitrogen fertilizers is preferably no later than 2-3 weeks before harvesting. In addition, the full conversion of nitrates in proteins is hampered by poor lighting, excessive humidity and imbalance of nutrient elements (lack of phosphorus and potassium). Do not be takenlated by promotional greenhouse vegetables. For example, 2 kg of greenhouse cucumbers eaten in one reception can cause life-threatening poisoning with nitrates. It is also necessary to know, mainly in which parts of the plant, the nitrates are accumulated: the cabbage - in the numor, in the carrot - in the core, at zucchini, cucumbers, watermelons, melons, potatoes - in the peel. Melon and watermelon should not have an immature pulp, adjacent to the crust. Cucumbers are better to clean and cut off their attachment to the stalk. In green crops, nitrates accumulate in stems (parsley, salad, dill, celery). The content of nitrates in various parts of plants is uneven: in the cutters of leaves, stem, the root content is 1.5-4.0 times higher than in the leaves. The World Health Organization considers the allowable content of nitrates in dietary products to 300 mgNO 3 - per 1 kg of raw substance.(Pupils are recorded in notebooks: MPC (NO 3 - in dietary products) - 300 mg / kg.)

If the highest content of nitrates is marked in beets, cabbage, salad, green onions, then the lowest content of nitrates is in the onions, tomatoes, garlic, pepper, beans.

To raise environmentally friendly products, first of all, it is necessary to competently make nitrogen fertilizers in the soil: in strictly calculated doses and optimal deadlines. Grow vegetables, especially green crops, it is necessary at a good light, optimal indicators of soil moisture and temperature. And yet, to reduce the content of nitrates, vegetable crops are better to feed organic fertilizers. Incoming fertilizer, especially in excess doses, including organic fertilizer - manure, leads to the fact that nitrogen mineral compounds received in the plant do not fully turn into protein.

4th student. Spring cultures appear on the shelves and markets on the shelves: salad, spinach, green onions, cucumbers grown in a greenhouse in a closed soil. How to reduce the content of nitrates in them? List some of them.

1. Early cultures like parsley, dill, celery, must be put as a bouquet into the water sunlight. In such conditions, nitrates in the leaves for 2-3 hours are fully recycled and then practically not detected. After that, the greens can be used in writing without fears.

2. Beets, zucchini, pumpkin before cooking should be cut into small cubes and pour 2-3 times with warm water, withstanding 5-10 minutes. Nitrates are well soluble in water, especially warm, and washed out with water (look at the solubility table of acids, bases, salts). When washing and cleaning, 10-15% of nitrates are lost.

3. Ward vegetables reduces the content of nitrates by 50-80%.

4. Reduces the number of nitrates in vegetables, pickling, pickling.

5. With a debt of storage, the content of nitrates in vegetables is reduced.

But drying, preparation of juices and mashed potatoes, on the contrary, increase the number of nitrates.

1) cooking vegetables;

2) cleaning from the peel;

3) removal of sections of the greatest cluster of nitrates;

4) soaking.

In order to evaluate how real the danger of poisoning with nitrates, the calculated task is proposed for students.

A task. In the canteen beet, it contains an average of 1200 mg of nitrate ions per 1 kg. When cleaning beets, 10% of nitrates are lost, and during cooking - another 40%. Will the daily rate of nitrate consumption (325 mg) be exceeded, if you eat 200 g of boiled beet every day?

Given:

m (beets) \u003d 1 kg,

from(NO 3 -) \u003d 1200 mg / kg,

m. Max (NO 3 - per day) \u003d 325 mg,

m.(beets) \u003d 200 g (0.2 kg),

(loss with cleaning) \u003d 10%,

(Losses in cooking) \u003d 40%.

__________________________________

To find: m.(NO 3 - 200 g of boiled beet).

Decision

1 kg beets - 1200 mg NO 3 -,

0.2 kg beets - h. MG NO 3 -.

From here h. \u003d 240 mg (NO 3 -).

Overall share of the loss of nitrate ions:

(LOSS NO 3 -) \u003d 10% + 40% \u003d 50%.

Consequently, half of 24 mg or 120 mg NO 3 fall into the body.

Answer.After cleaning and cooking beets, the daily rate of nitrates (325 mg) contained in 200 g of the finished product (120 mg of NO 3 -) is not exceeded, it is possible to eat it.

Nitrates in the production of explosives

Teacher. Many explosive mixtures contain an oxidizing agent (metals or ammonium nitrates, etc.) and fuel (diesel fuel, aluminum, wood flour). Therefore, salts are potassium nitrate, barium nitrate, nitrate strontium and others - apply in pyrotechnics.

What nitrogen fertilizer together with aluminum and charcoal is part of the explosive mixture - ammonale?

Student. Ammonal also contains ammonium nitrate. The main reaction that proceeds with an explosion:

3NN 4 NO 3 + 2AL 3N 2 + 6N 2 O + AL 2 O 3 + Q..

High heat combustion of aluminum increases the energy of the explosion. The use of ammonium nitrate in the ammonal composition is based on its property to decompose during detonation with the formation of gaseous substances:

2NH 4 NO 3 (cr.) \u003d 2n 2 + 4N 2 O + O 2.

In the hands of terrorists, explosives brings peaceful people only suffering.

The sixth centuries continued the domination of black powder in military business. Now it is used as an explosive in highlights, in pyrotechnics (rockets, fireworks), as well as as a hunting gun. Black or smoky powder is a mixture of 75% potassium nitrate, 15% charcoal and 10% sulfur.

Experience. Burning of black or smoky powder

A black powder is prepared by mixing 7.5 g of potassium nitrate, 1 g of sulfur and 1.5 g of charcoal. Before mixing, each substance is crushed in a porcelain mortar. During the demonstration of the experience, the mixture is placed on the iron sheet and ignite the burning rays. The mixture burns, forming a cloud of smoke (thrust).

Teacher. What role does the Selitra play?

Student. Selith acts as an oxidizing agent when heated:

The use of nitrates and nitrites in medicine

5th student. Nitrate of silver AGNO 3, which ink fabric, paper, desks and hands (Lapis) are used as antimicrobial tool for skin treatment, for migrating warts(the teacher demonstrates the technique of causthing warts on his hand) and as an anti-inflammatory agent for chronic gastritis and stomach ulcer: patients prescribe 0.05% solution AGNO 3. Powdered metalsZn, mg, al, mixed with silver nitrate, used in firefall.

Basic nitrate bismuth VI (OH) 2 NO 3 prescribed inside with a stomach ulcer and duodenal ulcer as a binder and antiseptic agent. Outwardly - in ointments, powders in inflammatory skin diseases.

Salt sodium nitrite NANO 2 apply in medicine as an antispasmodic agent.

Application of nitrites in the food industry industry

6th student. Nitrites are used in sausage production: 7 g per 100 kg of minced. Nitrites give the sausage pink color, without them it is gray, like boiled meat, and has no product view. In addition, the presence of nitrites in the sausage is also necessary for another reason: they prevent the development of microorganisms that allocate toxic poisons.

Control of knowledge using the test "Nitrogen and its connections"

Option I.

1. The most durable molecule:

a) H 2; b) f 2; c) about 2; d) N 2.

2. Painting phenolphthalein in ammonia solution:

a) raspberry; b) green;

c) yellow; d) blue.

3. The degree of oxidation is +3 at the nitrogen atom in the connection:

a) NH 4 NO 3; b) Nano 3; c) NO 2; d) KNO 2.

4. With thermal decomposition of copper nitrate (II) formed:

a) nitrite of copper (II) and 2;

b) nitrogen oxide (IV) and 2;

c) copper oxide (II), the brown gas NO 2 and O 2;

d) copper hydroxide (II), N 2 and 2.

5. What ion is formed by a donor-acceptor mechanism?

but) ; b) NO 3 -; c) SL -; d) SO 4 2-.

6. Specify strong electrolytes:

a) nitric acid;

b) nitrate acid;

c) an aqueous solution of ammonia;

d) ammonium nitrate.

7. Hydrogen stands out when interacting:

a) zn + hno 3 (spz.);

b) Cu + HCl (P-P);

c) Al + NaOH + H 2 O;

d) Zn + H 2 SO 4 (RSC);

e) FE + HNO 3 (conc.).

8. Make the zinc reaction equation with a very diluted nitric acid, if one of the reaction products is ammonium nitrate. Specify the coefficient facing the oxidizing agent.

Give the names of substances A, B, C.

Option II.

1. We can not assemble the displacement of water:

a) nitrogen; b) hydrogen;

c) oxygen; d) ammonia.

2. The imminent ion reagent is a solution:

a) potassium sulfate; b) silver nitrate;

c) sodium hydroxide; d) barium chloride.

3. In the interaction of NNO 3 (conc.) With copper chips, gas is formed:

a) N 2 O; b) nn 3; c) NO 2; d) H 2.

4. With thermal decomposition of sodium nitrate formed:

a) sodium oxide, brown gas NO 2, O 2;

b) sodium nitrite and 2;

c) sodium, brown gas NO 2, O 2;

d) sodium hydroxide, N 2, O 2.

5. Azoto oxidation drying in ammonium sulfate:

a) -3; b) -1; c) +1; d) +3.

6. What kind of these substances reacts concentrated HNO 3 under normal conditions?

a) NAON; b) agsl; c) Al; d) Fe; d) Cu.

7. Specify the number of ions in the abbreviated ionic equation for the interaction of sodium sulfate and silver nitrate:

a) 1; b) 2; in 3; d) 4.

8. Make an equation of magnesium interaction with dilute nitric acid, if one of the reaction products is a simple substance. Specify the coefficient factories in the equation before the oxidizing agent.

9. Write the reaction equations for the following transformations:

Give the names of substances A, B, C, D.

Answers to test questions

Option I.

1 - r; 2 - but; 3 - r; 4 - in; 5 - but; 6 - a, g; 7 - in, g; 8 – 10,

9. A - NH 3, B - NH 4 NO 3, C - NO,

Option II.

1 - r; 2 - in; 3 - in; 4 - b; 5 - but; 6 - A, D; 7 - in,

2Ag + + SO 4 2- \u003d AG 2 SO 4;

8 – 12,

9. A - NO, B - NO 2, C - HNO 3, D - NH 4 NO 3,

In the conclusion of the lesson, the teacher expresses his attitude towards the work done by students, assesses their speeches and answers.

LITERATURE

Gabrielyan O.S.. Chemistry-9. M.: Drop, 2001; Gabrielyan O.S, Ostrumov IG. Teacher's desk book. Chemistry. Grade 9. M.: Drop, 2002; Pichugina G.V.. Summarizing knowledge about the transformation of nitrogen compounds in the soil and in plants. Chemistry at school, 1997, № 7; Kharkov N.L..,
Lyashenko L.F., Baranova N.V. Caution - nitrates! Chemistry at school, 1999, No. 1; Zheleznyova Yu.V., Nazarenko V.M.. Educational environmental projects. Chemistry at school, 2000, № 3.

* "Red Precirate" is one of the mercury (II) HGO oxide modifications. ( Approx. Red.)

HNO 2. Physical properties condition solid Molar mass 47.0134 g / mol Density 1.685 (liquid) Thermal properties T. Plave. 42.35 ° C. T. Kip. 158 ° C. Chemical properties pK A. 3.4 Solubility in water 548 g / 100 ml Classification Reg. Cas Data is given for standard conditions (25 ° C, 100 kPa), unless otherwise indicated.

Azobic acid HNO 2 is weak monosocond acid, exists only in dilute aqueous solutions painted into a weak blue color and in the gas phase. Nitrical acid salts are called nitrites or nitrogen-acid. Nitrites are much more resistant than HNO 2, they are all toxic.

Structure

In the gas phase, the planar nitrogenous acid molecule exists in the form of two configurations cis and trance-.


cis-isomer	Trans-Isomer

At room temperature, a trans isomer prevails: this structure is more stable. So, for cis-hno 2 (g) Dg ° F \u003d -42,59 kJ / mol, and for trans-HNO 2 (g) DG \u003d -44.65 kJ / mol.

Chemical properties

In aqueous solutions there is an equilibrium:

$\\ mathsf (2hno_2 \\ rightleftarrows n_2o_3 + h_2o \\ rightleftarrows no \\ Uparrow + No_2 \\ Uparrow + H_2O)$

When the solution is heated, nitrogenous acid decomposes with the release and formation of nitric acid:

$\\ Mathsf (3hno_2 \\ rightleftarrows hno_3 + 2no \\ Uparrow + H_2O)$

HNO 2 is weak acid. In aqueous solutions, dissociates (k d \u003d 4.6 · 10 -4), a little stronger than acetic acid. Easily displaces stronger salts with stronger acids:

$\\ Mathsf (H_2SO_4 + 2Nano_2 \\ Rightarrow NA_2SO_4 + 2HNO_2)$

Nitrogenic acid manifests both oxidative and rehabilitation properties. With the action of stronger oxidants (hydrogen peroxide, chlorine, potassium permanganate) oxidizes to nitric acid:

$\\ MathSF (HNO_2 + H_2O_2 \\ RIGHTARROW HNO_3 + H_2O)$ $\\ MathSF (HNO_2 + CL_2 + H_2O \\ RIGHTARROW HNO_3 + 2HCl)$ $\\ mathsf (5hno_2 + 2kmno_4 + hno_3 \\ rightarrow 2mn (no_3) _2 + 2kno_3 + 3H_2O)$

At the same time, it is capable of oxidizing substances with reducing properties:

\\ Mathsf (2hno_2 + 2hi \\ rightarrow 2no \\ Uparrow + i_2 + 2H_2O)

Obtaining

Nitroxy acid can be obtained when dissolved nitrogen oxide (III) N 2 O 3 in water:

$\\ Mathsf (N_2O_3 + H_2O \\ RIGHTARROW 2HNO_2)$ $\\ Mathsf (2no_2 + h_2o \\ rightarrow hno_3 + hno_2)$

Application

Azobic acid is used to diazotize primary aromatic amines and formation of diazonium salts. Nitrites are used in organic synthesis in the production of organic dyes.

Physiological action

Nitrogenous acid is toxic, and has a pronounced mutagenic effect, since it is a deaminting agent.

Sources

Karapetyanz M. Kh., Drakin S. I. General and inorganic chemistry. M.: Chemistry1994