The use of ammonium chloride in pharmacy

Ammonium chloride has a diuretic effect; however, as an acid-forming agent, ammonium chloride is an effective agent for correcting alkalosis.

As a diuretic, ammonium chloride is sometimes prescribed for edema of cardiac origin.

Ammonium chloride also has an expectorant effect and is used for bronchitis, pneumonia, etc.

Gravimetric analysis

Work sequence: 1. Precipitation: 1. FeCl3 solution is taken for analysis into a clean beaker. 2. Acidify it with 3-5 ml of 2N. HNO3 solution and heat gently without boiling. 3...

Iron in soils. Methods for the determination of iron

A 5 g sample of air-dry soil, sifted through a sieve with 1 mm holes, is placed in a flask and 250 ml of 0.2 N HCL solution is added, mixed and infused for a day. Suspensions are filtered...

Determination of diacetyl and acetoin in alcoholic beverages

To standardize the iron (III) chloride solution, complexometric titration was carried out. An aliquot of 1.00 of the prepared solution of iron (III) chloride was placed in a volumetric flask with a capacity of 100.0...

Complex (coordination) compounds are extremely widespread in animate and inanimate nature and are used in industry, agriculture, science, and medicine. So, chlorophyll is a complex compound of magnesium with porphyrins ...

Preparation of ammonium tetrachlorozincate and study of its properties

ammonium tetrachlorozincate chemical preparation Ammonium tetrachlorozincate is used in electroplating and soldering, is part of fluxes. Soldering is a technological operation...

Preparation of ammonium tetrachlorozincate and study of its properties

There are several ways to obtain ammonium tetrachlorozincate. 1. The first method is based on the initial production of zinc chloride and its further interaction with ammonium chloride, until the precipitate dissolves ...

The alkylation process on the example of obtaining ethylbenzene in the presence of an aluminum chloride catalyst

The performance of the alkylation stage for 100% ethylbenzene is: or where 10000 is the performance based on 100% ethylbenzene, t/year; 8000 - number of working hours; 4 - loss of ethylbenzene at the stages of isolation, %; 106 is the molar mass of ethylbenzene...

The production of commercial calcium chloride from the still liquid of soda production consists in the sequential evaporation of the still liquid from a concentration of ~ 10% CaCl2 to 67%, required by the GOST conditions for the melted product ...

Properties and production of calcium chloride

The production of fused calcium chloride from the mother liquor of chlorate production, which contains 4–5 times more CaCl2 than the still liquid, is much more economical. Here, however...

Properties and production of calcium chloride

Calcium hydroxide is formed by mixing calcium chloride, ground lime and water in a stoichiometric ratio. It can be isolated from the distillation liquid without evaporating it, or at a certain stage of evaporating it ...

Properties and production of calcium chloride

Obtaining calcium chloride by this method consists in the dissolution of limestone in hydrochloric acid, in the purification of the resulting "raw" (crude) CaCl2 solution from impurities and in its dehydration. The product is cleaner...

§5. And for salts, the traditional one is an ionic bond

What form will a chemical bond have if it is formed by atoms of elements that are very different in electronegativity - for example, an alkali metal sodium and halogen chlorine?

atom electron sodium Na, located on the outer valence level, is a big fan of walking around the neighborhood and often even forgets to return home, to his native atomic nucleus. And then the sodium atom is left without its non-traveling electron and turns into cation Na+:

Na 0 − 1 e− = Na +

Seven electrons of an atom chlorine Cl On the contrary, they are incorrigible stay-at-homes; they do not like to visit, but they welcome guests with pleasure. If some neighboring electron turns towards them, then the atom chlorine will turn into anion Cl¯, which is called chloride-ion:

Cl 0 + 1 e− = Cl −

Ions of opposite charge will attract; it is formed ionic bond Na+ ~~~~ Cl-. So it turns out sodium chloride NaCl, known to all salt.

Natural table salt is a mineral.
In nature, this mineral is formed from salty sea or lake water. When it is cooled under a layer of salt solution, its crystals are found - transparent cubes sodium chloride. The ions that make up sodium chloride, form ionic crystal, consisting of cations sodium Na+ and chloride anion Cl-.

When a solid is formed from dissolved ions, cations and anions do not fit in the crystal randomly, but in such a way that positive and negative charges alternate with each other. Then you get a solid crystal cell salt NaCl consisting of ions.

Crystals of other salts are built in a similar way - sodium carbonate Na2CO3 (soda), ammonium chloride NH4Cl (ammonia), silver nitrate AgNO3 (lapis) and many others.

Is it true that all salts are built from individual ions that exist one by one? True, but there is a small "but" ...

The salt cation has some of the electron cloud left over, because even the most naughty naughty electron comes home from time to time. But a very large part of this cloud is shifted towards the salt anion. Therefore, an ionic bond is considered limiting case of a covalent polar bond.

Chemical bond. Crystal cell

The answers to the tasks are a word, a phrase, a number or a sequence of words, numbers. Write your answer without spaces, commas, or other extra characters.

Form start

1 Ammonium chloride contains chemical bonds:

1. ionic 2. covalent polar 3. covalent non-polar 4. hydrogen 5. metallic

2 Intermolecular hydrogen bonds in the liquid state are characteristic of:

1. hydrogen 2. water 3. ammonia 4. acetaldehyde 5. isobutane

3 Covalent non-polar chemical bonds are found in substances:

1. white phosphorus 2. phosphoric acid 3. ammonia

4. ethyl alcohol 5. rhombic sulfur

4 From the proposed list, select two compounds in which there is an ionic chemical bond.

1. Ca(ClO 2 ) 2 2. HClO 3 3.NH 4 Cl 4. HClO 4 5.C l2O 7

5 From the proposed list, select two compounds in which there is

covalent non-polar chemical bond.

1. Ca 2. H 2 3. AlCl 3 4. HClO 4 5.Cl 2

6 Chemical bonds are present in potassium sulfate:

1. ionic 2. covalent non-polar 3. covalent polar

4. hydrogen 5. metal

7 Both ionic and covalent chemical bonds exist in matter:

1. HCl 2. H 2 SO 4 3. NaOH 4. NH 4 Br 5. C 2 H 5 HE

8 From the proposed list, select two compounds between the molecules of which is formed

hydrogen bond.

1. phenol 2. diethyl ether 3. ethyl acetate 4. formic aldehyde 5. formic acid

9 From the proposed list, select two compounds in which there is a covalent

polar chemical bond.

1. CaCl 2 2. HCl 3. BaO 4. KSO 4 5. Сl 2

10 Non-molecular structure have:

1. potassium hydroxide 2. ammonia 3. acetic acid 4. nitric acid 5. graphite

11 Ionic bonds are realized in each of two substances:

1. BUTl 2 O 3 andFeCl 3 2. K 2 SandNaNO 3 3. KNO 2 and NO 2 4. HF and HCl 5. NaBr and NH 4 F

12 The atomic crystal lattice in the solid state has:

1. oxygen 2. white phosphorus 3. red phosphorus 4. diamond 5. sodium chloride

13 From the proposed list, select two compounds in which a chemical bond is formed

through a shared pair of electrons.

1. Ca 2. H 2 O 3. NaCl 4. CaO 5. Cl 2

14 The molecular structure is:

1. propanol-2 2. potassium acetate 3. carbon dioxide 4. sodium methoxide 5. calcium carbonate

15 All substances with ionic crystal lattices

1. hard 2. plastic 3. relatively volatile

4. highly soluble in water 5. have high melting points

16 From the proposed list, select two compounds between the molecules of which a hydrogen bond is formed.

1. Methane 2. Silane 3. Ammonia 4. Phosphine 5. Water

End of form

Task number 1.

Particles have the electronic configuration 1s 2 2s 2 2p 6:

Explanation: the configuration of a particle is given, the second energy level of which is filled (like neon). If a sodium atom gives up 1 electron, it will take on the configuration of neon, and if fluorine takes one electron, it will also become neon. The correct answer is 34.

Task number 2.

Arrange the elements in order of increasing atomic radius

Explanation: The atomic radius increases in the group from top to bottom and in the period from right to left, so the radius of sodium will be greater than the radius of magnesium, and the radius of potassium will be greater than that of sodium. The correct answer is 213.

Task number 3.

+2 oxidation state can exhibit both elements

Explanation: The oxidation state +2 is usually shown by metals (alkaline earth or transition), since metals are good reducing agents (that is, they donate electrons), so we will choose magnesium and chromium (MgO, CrSO4). And non-metals that have many oxidation states, for example, carbon and nitrogen (CO, NO), can also exhibit such an oxidation state. The correct answer is 13.

Task number 4.

Ammonium chloride contains chemical bonds

2. Covalent polar

3. Covalent non-polar

4. Hydrogen

5. Metal

Explanation: ammonium chloride - NH4Cl. Hydrogen and nitrogen are connected using a covalent polar bond, and the ammonium ion with the chlorine ion is connected using an ionic bond (an ionic bond connects metal and non-metal ions, but here the ammonium ion behaves like a metal). The correct answer is 12.

Task number 5.

Establish a correspondence between the formula of a substance and the class to which this substance belongs.

Substance formula

1. Salt medium

2. Acid oxide

3. Non-salt forming oxide

4. Sour salt

Explanation: NH4HSO4 - ammonium hydrogen sulfate, acid salt

KClO4 - potassium perchlorate - medium salt

N2O is a non-salt-forming oxide (because it does not have a corresponding acid)

The correct answer is 413.

Task number 6.

From the proposed list of substances, select two substances, with each of which copper reacts

1. Zinc chloride (solution)

2. Sodium sulfate (solution)

3. Diluted nitric acid

4. Concentrated sulfuric acid

5. Aluminum oxide

Explanation: copper is in the series of metal voltages after hydrogen, therefore it cannot displace zinc and sodium from their salts and aluminum from oxide. But copper reacts with acids:

1. With dilute nitric acid

3Сu+8HNO3 → 3Cu(NO3)2 + 4H2O + 2NO

2. With concentrated sulfuric acid

Cu + 2H2SO4 (conc) → CuSO4 + SO2 + 2H2O

The correct answer is 34.

Task number 7.

From the proposed list of substances, select two substances, with each of which carbon dioxide reacts

1. Iron oxide (III)

2. Calcium oxide

3. Concentrated nitric acid

4. Chromium (III) hydroxide

5. Potassium hydroxide

Explanation: CO2 is a salt-forming oxide, which means it reacts with alkaline earth metal oxides to form salts:

CaO + CO2 → CaCO3

and with alkali metal hydroxides to form salt and water:

CO2 + 2KOH → K2CO3 + H2O

The correct answer is 25.

Task number 8.

Aluminum hydroxide reacts with

Explanation: Al (OH) 3 is an insoluble base, it has amphoteric properties, which means it reacts like with acids:

2Al(OH)3 + 3H2SO4 → Al2(SO4)3 + 6H2O

so with the bases:

2Al(OH)3 + Sr(OH)2(s) → Sr(AlO2)2 + 4H2O

The correct answer is 14.

Task number 9.

In a given transformation scheme

N2 → Ca3N2 → NH3

Explanation: in order to obtain calcium nitride from molecular nitrogen, we will carry out a reaction with calcium

3Ca + N2 → Ca3N2

now add water to get ammonia

Ca3N2 + 6H2O → 3Ca(OH)2 + 2NH3

The correct answer is 13.

Task number 10.

Establish a correspondence between the formula of a substance and the degree of oxidation of nitrogen in it

Substance formula

Nitrogen oxidation state

Explanation: in the ammonium ion, as in ammonia, nitrogen has an oxidation state of -3, in NO2F - +5, in NOCl - +3, BaN2O2 - +2. The correct answer is 1654.

Task number 11.

Establish a correspondence between simple substances and formulas of reagents with which they can interact

Reagent formulas

1. H2SO4(dil), Al

6. H2SO4(razb), S

Explanation: Br2 is a non-metal and from the list presented reacts with potassium hydroxide:

6KOH+3Br2 → 5KBr+KBrO3+3H2O

and displaces iodine from its salt:

Br2 + 2KI → 2KBr + I2

Hydrogen reacts with ethylene:

С2Н4 + Н2 → С2Н6

and with oxygen (with explosion):

2H2 + O2 → 2H2O

Sulfur reacts with oxygen:

and with aluminum:

3S + 2Al → Al2S3

Sodium reacts with dilute sulfuric acid:

Na + H2SO4(razb) → Na2SO4 + H2

and with gray:

2Na + S → Na2S

The correct answer is 2356.

Task number 12.

Establish a correspondence between the name of the compound and the general formula of the homologous series to which it belongs.

Connection name

A. Isobutane

B. Buten-2

V. Pentin-1

G. Trans-pentene-2

General formula

Explanation: isobutane (like butane itself) belongs to alkanes, they have the general formula CnH2n + 2.

Butene-2 ​​is an alkene, the general formula is CnH2n.

Pentyne-1 is an alkyne, the general formula is CnH2n-2.

Trans-pentene-2 ​​- (pentene-2 ​​isomer) refers to alkenes, they have the general formula - CnH2n.

The correct answer is 1232.

Task number 13.

The isomers of pentene-2 ​​are

1. Penten-1

2. Cyclopentane

3. Pentin-2

4. 2-methylpentene-2

5. Methylcyclopentane

Explanation: pentene-2 ​​is an alkene, CH3-CH=CH-CH2-CH3.

We can solve this problem in two ways:

1. Let's write the structural formulas of all answer options and analyze them

2. Let's write down the gross formulas of all answer options, because isomers have the same formula, but different structures.

The correct answer is 12.

Task number 14.

Cyclopropane, unlike propane, reacts with

1. Hydrogen

2. Oxygen

5. Hydrogen bromide

Explanation: cycloalkanes, unlike alkanes, enter into addition reactions, for example, with hydrogen or hydrogen bromide. Alkanes, on the other hand, are characterized by substitution reactions. The correct answer is 15.

Task number 15.

From the proposed list of substances, select two substances with which propanol-1 reacts.

1. Sodium hydroxide (solution)

2. 2-methylbutane

4. Carbon monoxide (IV)

5. Hydrobromic acid

Explanation: Propanol-1 is an alcohol. Alcohols react with metals:

2CH3-CH2-CH2-OH + 2K → 2CH3-CH2-CH2-OK + H2

And with hydrogen halides:

С3Н7OH + HBr → C3H7Br + H2O

The correct answer is 35.

Task number 16.

From the proposed list, select two substances with which methylamine reacts.

2. Hydrogen

3. Oxygen

4. Hydrogen bromide

5. Aluminum

Explanation: Methylamine is an amine. Amines are oxidized by oxygen (like all organic substances):

2CH3NH2 + 9/2O2 → N2 + 2CO2 + 5H2O

The amino group has basic properties and can attach hydrogen halides:

CH3NH2 + HBr → CH3NH3 + Br -

The correct answer is 34.

Task number 17.

In a given transformation scheme

HCOOH → CH3OH → CH3OCH3

substances X and Y, respectively, are:

Explanation: in the first reaction, methyl alcohol is formed from acetaldehyde, that is, the aldehyde is reduced to the corresponding alcohol. This can happen when interacting with hydrogen:

CHOH + H2 → CH3OH

In the second reaction, dimethyl ether is formed from methyl alcohol - this is a dehydration reaction (water detachment) occurs in the presence of a strong water-removing agent: 2CH3OH (H2SO4) → CH3OCH3 + H2O.

The correct answer is 15.

Task number 18.

Establish a correspondence between the reacting substances and the organic product, which is mainly formed during the interaction of these substances.

Reactive Substances

A. Methane (ex.) and chlorine

B. Acetylene and hydrogen

B. Propane and bromine

D. Cyclopropane and hydrogen

interaction product

1. Tetrachloromethane

2. Chloromethane

4. 1-bromopropane

5. 2-bromopropane

Explanation:

A - methane reacts with chlorine in the light, and chloromethane is obtained:

CH4 + Cl2 (hν) → CH3Cl + HCl

B - acetylene adds hydrogen to obtain ethane

CHΞCH + H2 → CH3-CH3

B - propane enters into a halogenation reaction with bromine, while bromine attaches to the second carbon atom (according to Markovnikov's rule)

CH3-CH2-CH3 + Br2 (hν) → CH3-CH(Br)-CH3 + HBr

G - cyclopropane reacts with hydrogen, while the cycle is broken and propane is formed

С3Н6 + Н2 → С3Н8

The correct answer is 2356.

Task number 19.

Establish a correspondence between the reacting substances and the carbon-containing product that is formed during the interaction of these substances.

Reactive Substances

A. Ethanol and sodium

B. Ethanol and hydrogen bromide

B. Ethane and bromine

D. Ethanol and methanol

interaction product

1. Ethyl sodium

2. Sodium ethylate

3. Bromoethane

4. Bromothene

5. Methylethanol

6. Methyl ethyl ether

Explanation: In the reaction of ethanol with sodium, sodium ethoxide is obtained:

2C2H5OH + 2Na → 2C2H5ONa + H2

When ethanol reacts with hydrogen bromide, bromoethane and water are obtained

C2H5OH + HBr → C2H5Br + H2O

When ethane reacts with bromine in the presence of light, bromoethane and hydrogen bromide are produced.

C2H6 + Br2 (hν) → C2H5Br + HBr

When alcohols interact with each other in the presence of a strong water-removing agent - sulfuric acid - ethers are obtained (in this case, methyl ethyl ether)

C2H5OH + CH3OH (H2SO4) → C2H5OCH3 + H2O

The correct answer is 2336.

Task number 20.

The interaction of sodium with water refers to reactions

1. catalytic

2. Homogeneous

3. Virtually irreversible

4. Redox

Explanation: we write the equation for the interaction of sodium with water:

2Na + 2H2O → 2NaOH + H2

In this reaction, hydrogen is released from the reaction mixture (and flies away forever), that is, the reaction cannot go in the opposite direction, that is, it is practically irreversible. Sodium changes the oxidation state from 0 to +1, and hydrogen, on the contrary, takes electrons (+1 → 0), which means this is a redox reaction.

The correct answer is 34.

Task number 21.

Reaction rate 2NO + O2 = 2NO2 + Q

decrease at

1. Catalyst application

2. Decrease in NO2 concentration

3. Increasing NO2 concentration

4. Reducing the pressure in the system

5. Decreased oxygen concentration

Explanation: when the pressure in the system decreases, the particles collide less often with each other, which reduces the reaction rate. With a decrease in the oxygen concentration, not all molecules of nitric oxide (II) can react with oxygen molecules (because there are fewer of them), this also contributes to a decrease in the reaction rate. The correct answer is 45.

Task number 22.

Establish a correspondence between the salt formula and the product released at the anode during the electrolysis of an aqueous solution of this substance.

Salt formula

Anode product

1. Oxygen

2. Halogen

3. Hydrogen

Explanation: before solving this task, we recommend repeating the topic "Electrolysis". Anions settle on the anode. During the electrolysis of aqueous solutions of phosphates, oxygen is obtained at the anode, as in the electrolysis of aqueous solutions of fluorides. And during the electrolysis of aqueous solutions of halides (except for fluorine), the halogen itself precipitates. The correct answer is 1212.

Task number 23.

Establish a correspondence between the name of the salt and the environment of its aqueous solution.

Salt name

A. Potassium hydrosulfide

B. Sodium hydrosulfite

B. Potassium orthophosphate

D. Chromium(III) chloride

Solution medium

1. Neutral

3. Alkaline

Explanation: potassium hydrosulfide is formed by alkali - potassium hydroxide and weak hydrosulfide acid, and although it is an acidic salt, due to the strength of the hydroxide, its aqueous solution has an alkaline environment. The same can be said about potassium orthophosphate. In an aqueous solution of sodium hydrosulfite, the dissociation constant is greater than the hydrolysis constant, which means that the sodium hydrosulfite solution has an acidic environment, like a solution of chromium chloride (due to strong hydrochloric acid and a weak insoluble base). The correct answer is 3232.

Task number 24.

Establish a correspondence between the equation of a chemical reaction and the direction of displacement of chemical equilibrium with increasing pressure in the system:

Reaction equation

A. N2(g) + 3H2(g) ↔ 2NH3(g)

B. 2H2(g) + O2(g) ↔ 2H2O(g)

B. H2(g) + Cl2(g) ↔ 2HCl(g)

D. SO2(g) + Cl2(g) ↔ SO2Cl2(g)

Direction of displacement of chemical equilibrium

1. Towards the reaction products

2. Towards the starting materials

3. Practically does not move

Explanation: with an increase in pressure, the equilibrium shifts towards a decrease in the amount of gaseous substances, that is, towards a decrease in pressure; when pressure decreases, the equilibrium shifts in the direction of increasing amounts of gaseous substances, that is, in the direction of increasing pressure. If the reaction proceeds without changing the number of molecules of gaseous substances, then the pressure does not affect the equilibrium position in this system.

This means that in the first reaction, the equilibrium will shift towards the reaction products, as in the second. In the third reaction, the number of molecules on the right and left is the same, so the equilibrium is practically not shifted, and in the last reaction, the equilibrium is shifted to the right.

The correct answer is 1131.

Task number 25.

Establish a correspondence between substances and a reagent with which they can be distinguished from each other.

Substances

A. Acetylene and ethylene

B. Ethylene and ethane

B. Ethandiol-1,2 and ethanol

D. Phenol and ethanol

4. H2SO4 (solution)

Explanation: An ammonia solution of silver oxide reacts with alkynes (acetylene), but not with alkenes (ethylene). Alkenes are characterized by addition reactions (since they have unsaturated bonds), unlike alkanes. Distinguish ethylene and ethane using bromine water. Polyhydric alcohols react with copper hydroxide, unlike monohydric alcohols (such a reaction is qualitative for polyhydric alcohols). Phenol and ethanol are distinguished by bromine water, with which phenol reacts. The correct answer is 2151.

Task number 26.

The most toxic ions for a living organism are:

Explanation:

Mercury toxic in any form. Mercury under natural conditions rather quickly turns into a volatile toxic compound - methylmercury chloride. In the body, methylmercury ions quickly enter the erythrocytes, liver and kidneys, settle in the brain, causing serious irreversible cumulative disorders of the central nervous system. This eventually leads to general and cerebral palsy, deformities of the limbs, especially fingers, difficulty swallowing, convulsions and death. Mercury blocks the activity of a number of important enzymes, in particular carbonic anhydrase, carboxypeptidase, alkaline phosphatase. Easily replaces cobalt in corrinoids, perverting metabolic reactions associated with vitamin B12. Damage to the mechanism of DNA biosynthesis due to vitamin B12 deficiency is the cause of megaloblastic anemia and the most common form, pernicious anemia, which leads to degenerative changes in the nervous system. (Source - http://www.forens-med.ru/book.php?id=1839)

Copper is a necessary cofactor for several important enzymes that catalyze a variety of redox reactions, without which normal life is impossible. Copper is included as a necessary element in the composition of cytochrome oxidase, tyronase and other proteins. Their biological role is associated with the processes of hydroxylation, oxygen and electron transfer, and oxidative catalysis. In the tissues of a healthy body, the concentration of copper throughout life is maintained strictly constant. Normally, there is a system that prevents the continuous accumulation of honey in tissues by limiting its absorption or stimulating its excretion. Chronic excess of copper in tissues In case of corresponding diseases, they cause toxicosis: it leads to stunting, hemolysis, decrease in hemoglobin content, degradation of liver, kidney, and brain tissues. About 95% of copper in the body is present in the blood glycoprotein ceruloplasmin. The fact of the lack of this protein is known. In Wilson-Konovalov's disease - an inborn deficiency of metabolism (hepatolenticular degeneration). Due to a genetic defect in the synthesis of ceruloplasmin, its content in the blood is sharply reduced. As a result, copper does not bind into a complex with a stability constant that is normal for the organism. This leads to a deficiency in honey and in chain and metabolic reactions, leading to a natural for a healthy body synthesis in connective tissue. To carry out the normal process of cross-linking of elastin and collagen monomers, there is not enough active Si-lysole oxidase. On the other hand, the “released” copper ions, having lost essentially the only normal consumer, are deposited in specific tissues (liver, brain nuclei, kidneys, endocrine glands, iris), where they have a direct toxic effect. A paradoxical situation is created of an excess of copper in specific tissues with its deficiency in the normal metabolic chain. (Source - http://www.forens-med.ru/book.php?id=1839).

The correct answer is 13.

Task number 27.

To 200 g of a 5% ammonium chloride solution, 15 g of the same salt and the same number of grams of water were added. What is the mass fraction of ammonium chloride in the resulting solution?

Explanation: find the mass of pure ammonium chloride

m (pure water) \u003d 200 x 0.05 \u003d 10 g

Find the mass fraction of ammonium chloride in the resulting solution:

ω(NH4Cl) = 25/230 x 100% = 11%

Answer: 11%.

Task number 28.

What volume of nitrogen (N.O.) is formed during the complete combustion of 20 liters of ammonia in excess oxygen?

Explanation: write the reaction equation

4NH3 + 3O2 →2N2 + 6H2O

Find the amount of ammonia substance:

n(NH3) = 20/22.4 = 0.9 mol

The amount of nitrogen substance is two times less than the amount of ammonia substance (we look at the coefficients: 4 and 2)

Now we find the volume of the resulting nitrogen:

V(N2) = 0.45 x 22.4 = 10 l

Answer: 10 l.

Task number 29.

Calculate the mass of aluminum chloride formed by the action of excess chlorine on 2.7 g of aluminum.

Explanation: write the reaction equation:

2Al + 3Cl2 → 2AlCl3

Find the amount of aluminum substance that reacted:

n(Al) = 2.7/27 = 0.1 mol

The amount of aluminum chloride substance is equal to the amount of aluminum substance, since the coefficients are the same.

n(AlCl3) = n(Al) = 0.1 mol

Now we find the mass of the resulting aluminum chloride:

m (AlCl3) \u003d 0.1 x (27 + 106.5) \u003d 13.35 g

Answer: 13.35 g.

Task number 30.

Using the electron balance method, write the equation for the reaction

K2S + ... + KBrO4 → S + KBr + ...

Determine the oxidizing agent and reducing agent.

Explanation:

The environment in this solution is alkaline (due to potassium), but potassium hydroxide is obtained in the reaction, then the hydrogen on the left will be in the form of water.

K2S + H2O + KBrO4 → S + KBr + KOH

Bromine and sulfur change their oxidation states. Let's write the balance.

S -2 -2e → S 0 | four

Br +7 +8e → Br -1 | one

Let's set up the coefficients.

4K2S + 4Н2О + KBrO4 → 4S + KBr + 8KOH

Task number 31.

Aluminum oxide was fused with sodium hydroxide. The reaction product was added to an ammonium chloride solution. The released gas with a pungent odor is absorbed by sulfuric acid. The middle salt thus formed was calcined.

Write down the equations of the described reactions.

Explanation: aluminum oxide reacts with sodium hydroxide

Al2O3 + 2NaOH (t) → 2NaAlO2 + H2O

Sodium aluminate reacts with ammonium chloride in solution (additional water is added)

NaAlO2 + NH4Cl +H2O → NaCl + Al(OH)3↓ + NH3

The released gas - ammonia, reacts with sulfuric acid to form ammonium sulfate

NH3 + H2SO4 → (NH4)2SO4

Now the resulting ammonium sulfate is subjected to thermal decomposition

(NH4)2SO4 (t) → NH3 + NH4HSO4

Task number 32.

Write the reaction equations that can be used to carry out the following transformations?

Methane → X1 → X2 → ethene → ethanal → ethanol

When writing reaction equations, use the structural formulas of organic compounds.

Explanation: methane reacts with bromine in the light by a radical substitution reaction

CH4 + Br2 (hν) → CH3Br + HBr

Then we write down the Wurtz reaction (doubling of alkanes) - we get ethane

CH3-CH (Ni, t) → CH2=CH2 + H2

Oxidize ethene with oxygen in the presence of a catalyst

2СH2=CH2 + O2 (kat) → 2CH3CHO

Hydrogenate ethanol to get ethanol

CH3CH=O + H2 → CH3-CH2-OH

Task 33.

Calculate the mass fraction of sulfuric acid in a solution obtained by mixing 200 ml of a 15% solution of sulfuric acid with a density of 1.2 g/ml and 150 ml of a 10% solution of barium nitrate with a density of 1.04 g/ml.

170133 0

Each atom has a certain number of electrons.

Entering into chemical reactions, atoms donate, acquire, or socialize electrons, reaching the most stable electronic configuration. The configuration with the lowest energy is the most stable (as in noble gas atoms). This pattern is called the "octet rule" (Fig. 1).

Rice. one.

This rule applies to all connection types. Electronic bonds between atoms allow them to form stable structures, from the simplest crystals to complex biomolecules that eventually form living systems. They differ from crystals in their continuous metabolism. However, many chemical reactions proceed according to the mechanisms electronic transfer, which play an important role in the energy processes in the body.

A chemical bond is a force that holds together two or more atoms, ions, molecules, or any combination of them..

The nature of the chemical bond is universal: it is an electrostatic force of attraction between negatively charged electrons and positively charged nuclei, determined by the configuration of the electrons in the outer shell of atoms. The ability of an atom to form chemical bonds is called valency, or oxidation state. The concept of valence electrons- electrons that form chemical bonds, that is, those located in the most high-energy orbitals. Accordingly, the outer shell of an atom containing these orbitals is called valence shell. At present, it is not enough to indicate the presence of a chemical bond, but it is necessary to clarify its type: ionic, covalent, dipole-dipole, metallic.

The first type of connection isionic connection

According to Lewis and Kossel's electronic theory of valency, atoms can achieve a stable electronic configuration in two ways: first, by losing electrons, becoming cations, secondly, acquiring them, turning into anions. As a result of electron transfer, due to the electrostatic force of attraction between ions with charges of the opposite sign, a chemical bond is formed, called Kossel " electrovalent(now called ionic).

In this case, anions and cations form a stable electronic configuration with a filled outer electron shell. Typical ionic bonds are formed from cations of T and II groups of the periodic system and anions of non-metallic elements of groups VI and VII (16 and 17 subgroups - respectively, chalcogens and halogens). The bonds in ionic compounds are unsaturated and non-directional, so they retain the possibility of electrostatic interaction with other ions. On fig. 2 and 3 show examples of ionic bonds corresponding to the Kossel electron transfer model.

Rice. 2.

Rice. 3. Ionic bond in the sodium chloride (NaCl) molecule

Here it is appropriate to recall some of the properties that explain the behavior of substances in nature, in particular, to consider the concept of acids and grounds.

Aqueous solutions of all these substances are electrolytes. They change color in different ways. indicators. The mechanism of action of indicators was discovered by F.V. Ostwald. He showed that the indicators are weak acids or bases, the color of which in the undissociated and dissociated states is different.

Bases can neutralize acids. Not all bases are soluble in water (for example, some organic compounds that do not contain -OH groups are insoluble, in particular, triethylamine N (C 2 H 5) 3); soluble bases are called alkalis.

Aqueous solutions of acids enter into characteristic reactions:

a) with metal oxides - with the formation of salt and water;

b) with metals - with the formation of salt and hydrogen;

c) with carbonates - with the formation of salt, CO 2 and H 2 O.

The properties of acids and bases are described by several theories. In accordance with the theory of S.A. Arrhenius, an acid is a substance that dissociates to form ions H+ , while the base forms ions HE- . This theory does not take into account the existence of organic bases that do not have hydroxyl groups.

In line with proton Bronsted and Lowry's theory, an acid is a substance containing molecules or ions that donate protons ( donors protons), and the base is a substance consisting of molecules or ions that accept protons ( acceptors protons). Note that in aqueous solutions, hydrogen ions exist in a hydrated form, that is, in the form of hydronium ions H3O+ . This theory describes reactions not only with water and hydroxide ions, but also carried out in the absence of a solvent or with a non-aqueous solvent.

For example, in the reaction between ammonia NH 3 (weak base) and hydrogen chloride in the gas phase, solid ammonium chloride is formed, and in an equilibrium mixture of two substances there are always 4 particles, two of which are acids, and the other two are bases:

This equilibrium mixture consists of two conjugated pairs of acids and bases:

1)NH 4+ and NH 3

2) HCl and Cl ‑

Here, in each conjugated pair, the acid and base differ by one proton. Every acid has a conjugate base. A strong acid has a weak conjugate base, and a weak acid has a strong conjugate base.

The Bronsted-Lowry theory makes it possible to explain the unique role of water for the life of the biosphere. Water, depending on the substance interacting with it, can exhibit the properties of either an acid or a base. For example, in reactions with aqueous solutions of acetic acid, water is a base, and with aqueous solutions of ammonia, it is an acid.

1) CH 3 COOH + H 2 O ↔ H 3 O + + CH 3 SOO- . Here, an acetic acid molecule donates a proton to a water molecule;

2) NH3 + H 2 O ↔ NH4 + + HE- . Here the ammonia molecule accepts a proton from the water molecule.

Thus, water can form two conjugated pairs:

1) H 2 O(acid) and HE- (conjugate base)

2) H 3 O+ (acid) and H 2 O(conjugate base).

In the first case, water donates a proton, and in the second, it accepts it.

Such a property is called amphiprotonity. Substances that can react as both acids and bases are called amphoteric. Such substances are often found in nature. For example, amino acids can form salts with both acids and bases. Therefore, peptides readily form coordination compounds with the metal ions present.

Thus, the characteristic property of an ionic bond is the complete displacement of a bunch of binding electrons to one of the nuclei. This means that there is a region between the ions where the electron density is almost zero.

The second type of connection iscovalent connection

Atoms can form stable electronic configurations by sharing electrons.

Such a bond is formed when a pair of electrons is shared one at a time. from each atom. In this case, the socialized bond electrons are distributed equally among the atoms. An example of a covalent bond is homonuclear diatomic H molecules 2 , N 2 , F 2. Allotropes have the same type of bond. O 2 and ozone O 3 and for a polyatomic molecule S 8 and also heteronuclear molecules hydrogen chloride HCl, carbon dioxide CO 2, methane CH 4, ethanol FROM 2 H 5 HE, sulfur hexafluoride SF 6, acetylene FROM 2 H 2. All these molecules have the same common electrons, and their bonds are saturated and directed in the same way (Fig. 4).

For biologists, it is important that the covalent radii of atoms in double and triple bonds are reduced compared to a single bond.

Rice. four. Covalent bond in the Cl 2 molecule.

Ionic and covalent types of bonds are two limiting cases of many existing types of chemical bonds, and in practice most of the bonds are intermediate.

Compounds of two elements located at opposite ends of the same or different periods of the Mendeleev system predominantly form ionic bonds. As the elements approach each other within a period, the ionic nature of their compounds decreases, while the covalent character increases. For example, the halides and oxides of the elements on the left side of the periodic table form predominantly ionic bonds ( NaCl, AgBr, BaSO 4 , CaCO 3 , KNO 3 , CaO, NaOH), and the same compounds of the elements on the right side of the table are covalent ( H 2 O, CO 2, NH 3, NO 2, CH 4, phenol C6H5OH, glucose C 6 H 12 O 6, ethanol C 2 H 5 OH).

The covalent bond, in turn, has another modification.

In polyatomic ions and in complex biological molecules, both electrons can only come from one atom. It is called donor electron pair. An atom that socializes this pair of electrons with a donor is called acceptor electron pair. This type of covalent bond is called coordination (donor-acceptor, ordative) communication(Fig. 5). This type of bond is most important for biology and medicine, since the chemistry of the most important d-elements for metabolism is largely described by coordination bonds.

Pic. 5.

As a rule, in a complex compound, a metal atom acts as an electron pair acceptor; on the contrary, in ionic and covalent bonds, the metal atom is an electron donor.

The essence of the covalent bond and its variety - the coordination bond - can be clarified with the help of another theory of acids and bases, proposed by GN. Lewis. He somewhat expanded the semantic concept of the terms "acid" and "base" according to the Bronsted-Lowry theory. The Lewis theory explains the nature of the formation of complex ions and the participation of substances in nucleophilic substitution reactions, that is, in the formation of CS.

According to Lewis, an acid is a substance capable of forming a covalent bond by accepting an electron pair from a base. A Lewis base is a substance that has a lone pair of electrons, which, by donating electrons, forms a covalent bond with Lewis acid.

That is, the Lewis theory expands the range of acid-base reactions also to reactions in which protons do not participate at all. Moreover, the proton itself, according to this theory, is also an acid, since it is able to accept an electron pair.

Therefore, according to this theory, cations are Lewis acids and anions are Lewis bases. The following reactions are examples:

It was noted above that the subdivision of substances into ionic and covalent ones is relative, since there is no complete transfer of an electron from metal atoms to acceptor atoms in covalent molecules. In compounds with an ionic bond, each ion is in the electric field of ions of the opposite sign, so they are mutually polarized, and their shells are deformed.

Polarizability determined by the electronic structure, charge and size of the ion; it is higher for anions than for cations. The highest polarizability among cations is for cations of a larger charge and smaller size, for example, for Hg 2+ , Cd 2+ , Pb 2+ , Al 3+ , Tl 3+. Has a strong polarizing effect H+ . Since the effect of ion polarization is two-way, it significantly changes the properties of the compounds they form.

The third type of connection isdipole-dipole connection

In addition to the listed types of communication, there are also dipole-dipole intermolecular interactions, also known as van der Waals .

The strength of these interactions depends on the nature of the molecules.

There are three types of interactions: permanent dipole - permanent dipole ( dipole-dipole attraction); permanent dipole - induced dipole ( induction attraction); instantaneous dipole - induced dipole ( dispersion attraction, or London forces; rice. 6).

Rice. 6.

Only molecules with polar covalent bonds have a dipole-dipole moment ( HCl, NH 3, SO 2, H 2 O, C 6 H 5 Cl), and the bond strength is 1-2 debye(1D \u003d 3.338 × 10 -30 coulomb meters - C × m).

In biochemistry, another type of bond is distinguished - hydrogen connection, which is a limiting case dipole-dipole attraction. This bond is formed by the attraction between a hydrogen atom and a small electronegative atom, most often oxygen, fluorine and nitrogen. With large atoms that have a similar electronegativity (for example, with chlorine and sulfur), the hydrogen bond is much weaker. The hydrogen atom is distinguished by one essential feature: when the binding electrons are pulled away, its nucleus - the proton - is exposed and ceases to be screened by electrons.

Therefore, the atom turns into a large dipole.

A hydrogen bond, unlike a van der Waals bond, is formed not only during intermolecular interactions, but also within one molecule - intramolecular hydrogen bond. Hydrogen bonds play an important role in biochemistry, for example, for stabilizing the structure of proteins in the form of an α-helix, or for the formation of a DNA double helix (Fig. 7).

Fig.7.

Hydrogen and van der Waals bonds are much weaker than ionic, covalent, and coordination bonds. The energy of intermolecular bonds is indicated in Table. one.

Table 1. Energy of intermolecular forces

Note: The degree of intermolecular interactions reflect the enthalpy of melting and evaporation (boiling). Ionic compounds require much more energy to separate ions than to separate molecules. The melting enthalpies of ionic compounds are much higher than those of molecular compounds.

The fourth type of connection -metallic bond

Finally, there is another type of intermolecular bonds - metal: connection of positive ions of the lattice of metals with free electrons. This type of connection does not occur in biological objects.

From a brief review of the types of bonds, one detail emerges: an important parameter of an atom or ion of a metal - an electron donor, as well as an atom - an electron acceptor is its the size.

Without going into details, we note that the covalent radii of atoms, the ionic radii of metals, and the van der Waals radii of interacting molecules increase as their atomic number in the groups of the periodic system increases. In this case, the values ​​of the ion radii are the smallest, and the van der Waals radii are the largest. As a rule, when moving down the group, the radii of all elements increase, both covalent and van der Waals.

The most important for biologists and physicians are coordination(donor-acceptor) bonds considered by coordination chemistry.

Medical bioinorganics. G.K. Barashkov