Where is chlorine used? Chlorine is a very strong oxidizing agent. How was this element discovered?

Element of the VII subgroup of D.I. Mendeleev’s Periodic Table. At the external level there are 7 electrons, therefore, when interacting with reducing agents, chlorine shows its oxidizing properties, attracting a metal electron to itself.

Physical properties of chlorine.

Chlorine is a yellow gas. Has a pungent odor.

Chemical properties of chlorine.

Free chlorine very active. It reacts with all simple substances except oxygen, nitrogen and noble gases:

Si + 2 Cl 2 = SiCl 4 + Q.

When interacting with hydrogen at room temperature there is practically no reaction, but as soon as lighting acts as an external influence, a chain reaction occurs, which has found its application in organic chemistry.

When heated, chlorine is able to displace iodine or bromine from their acids:

Cl 2 + 2 HBr = 2 HCl + Br 2 .

Chlorine reacts with water, partially dissolving in it. This mixture is called chlorine water.

Reacts with alkalis:

Cl 2 + 2NaOH = NaCl + NaClO + H 2 O (cold),

Cl 2 + 6KOH = 5KCl + KClO 3 + 3 H 2 O (heat).

Getting chlorine.

1. Electrolysis of the sodium chloride melt, which proceeds according to the following scheme:

2. Laboratory method for producing chlorine:

MnO 2 + 4HCl = MnCl 2 + Cl 2 + 2H 2 O.

No matter how negatively we view public restrooms, nature dictates its own rules, and we have to visit them. In addition to natural (for a given place) odors, another common aroma is bleach used to disinfect the room. It got its name because of the main active ingredient in it - Cl. Let us learn about this chemical element and its properties, and also characterize chlorine by position in the periodic table.

How was this element discovered?

A chlorine-containing compound (HCl) was first synthesized in 1772 by the British priest Joseph Priestley.

Two years later, his Swedish colleague Karl Scheele was able to describe a method for isolating Cl using the reaction between hydrochloric acid and manganese dioxide. However, this chemist did not understand that as a result a new chemical element was synthesized.

It took scientists almost 40 years to learn how to produce chlorine in practice. This was first done by the British Humphry Davy in 1811. At the same time, he used a different reaction than his theoretic predecessors. Davy used electrolysis to break down NaCl (known to most as table salt) into its components.

After studying the resulting substance, the British chemist realized that it was elemental. After this discovery, Davy not only named it chlorine, but was also able to characterize chlorine, although it was very primitive.

Chlorine turned into chlorine (chlore) thanks to Joseph Gay-Lussac and in this form exists in French, German, Russian, Belarusian, Ukrainian, Czech, Bulgarian and some other languages ​​today. In English the name "chlorine" is still used, and in Italian and Spanish "chloro".

The element in question was described in more detail by Jens Berzelius in 1826. It was he who was able to determine its atomic mass.

What is chlorine (Cl)

Having considered the history of the discovery of this chemical element, it is worth learning more about it.

The name chlorine was derived from the Greek word χλωρός (“green”). It was given because of the yellowish-greenish color of this substance

Chlorine itself exists as a diatomic gas, Cl2, but it is practically never found in nature in this form. More often it appears in various compounds.

In addition to its distinctive hue, chlorine is characterized by a sweetish-acrid odor. It is a very toxic substance, therefore, when released into the air and inhaled by a person or animal, it can lead to their death within a few minutes (depending on the concentration of Cl).

Since chlorine is almost 2.5 times heavier than air, it will always be located below it, that is, near the ground. For this reason, if you suspect the presence of Cl, you should climb as high as possible, since there will be a lower concentration of this gas.

Also, unlike some other toxic substances, chlorine-containing substances have a characteristic color, which can allow them to be visually identified and action taken. Most standard gas masks help protect the respiratory system and mucous membranes from Cl. However, for complete safety, more serious measures must be taken, including neutralizing the toxic substance.

It is worth noting that it was with the use of chlorine as a poisonous gas by the Germans in 1915 that its history began. chemical weapon. As a result of the use of almost 200 tons of the substance, 15 thousand people were poisoned in a few minutes. A third of them died almost instantly, a third received permanent damage, and only 5 thousand managed to escape.

Why is such a dangerous substance still not banned and is mined annually in millions of tons? It's all about its special properties, and to understand them, it is worth considering the characteristics of chlorine. The easiest way to do this is using the periodic table.

Characteristics of chlorine in the periodic system

Chlorine as a halogen

In addition to its extreme toxicity and pungent odor (characteristic of all representatives of this group), Cl is highly soluble in water. Practical confirmation of this is the addition of chlorine-containing detergents to pool water.

Upon contact with moist air the substance in question begins to smoke.

Properties of Cl as a non-metal

When considering the chemical characteristics of chlorine, it is worth paying attention to its non-metallic properties.

It has the ability to form compounds with almost all metals and non-metals. An example is the reaction with iron atoms: 2Fe + 3Cl 2 → 2FeCl 3.

It is often necessary to use catalysts to carry out reactions. H2O can play this role.

Often reactions with Cl are endothermic (they absorb heat).

It is worth noting that in crystalline form (in powder form), chlorine interacts with metals only when heated to high temperatures.

Reacting with other non-metals (except O 2, N, F, C and inert gases), Cl forms compounds - chlorides.

When reacting with O 2, extremely unstable oxides are formed that are prone to decomposition. In them, the oxidation state of Cl can manifest itself from +1 to +7.

When interacting with F, fluorides are formed. Their degree of oxidation may be different.

Chlorine: characteristics of the substance in terms of its physical properties

Besides chemical properties, the element in question also has physical ones.

Effect of temperature on the state of aggregation of Cl

Having examined the physical characteristics of the element chlorine, we understand that it is capable of transforming into different states of aggregation. It all depends on the temperature.

In its normal state, Cl is a gas with highly corrosive properties. However, it can easily liquefy. This is affected by temperature and pressure. For example, if it is 8 atmospheres and the temperature is +20 degrees Celsius, Cl 2 is an acid-yellow liquid. It is capable of maintaining this state of aggregation up to +143 degrees, if the pressure also continues to increase.

When it reaches -32 °C, the state of chlorine ceases to depend on pressure, and it continues to remain liquid.

Crystallization of the substance (solid state) occurs at -101 degrees.

Where does Cl exist in nature?

Having considered general characteristics chlorine, it is worth finding out where such a complex element can be found in nature.

Due to its high reactivity, it is almost never found in its pure form (which is why it took scientists years to learn how to synthesize it when they first studied this element). Typically, Cl is found in compounds in various minerals: halite, sylvite, kainite, bischofite, etc.

Most of all, it is found in salts extracted from sea or ocean water.

Effect on the body

When considering the characteristics of chlorine, it has already been said more than once that it is extremely toxic. Moreover, atoms of the substance are contained not only in minerals, but also in almost all organisms, from plants to humans.

Due to their special properties, Cl ions penetrate cell membranes better than others (therefore, more than 80% of all chlorine in the human body is located in the intercellular space).

Together with K, Cl is responsible for the regulation of water-salt balance and, as a consequence, for osmotic equality.

Despite such an important role in the body, in its pure form Cl 2 kills all living things - from cells to entire organisms. However, in controlled doses and with short-term exposure, it does not have time to cause damage.

A striking example of the latter statement is any swimming pool. As you know, water in such institutions is disinfected with Cl. Moreover, if a person rarely visits such an establishment (once a week or a month), it is unlikely that he will suffer from the presence of this substance in the water. However, employees of such institutions, especially those who spend almost the entire day in the water (rescuers, instructors), often suffer from skin diseases or have weakened immunity.

In connection with all this, after visiting the pools, you should definitely take a shower - to wash off possible chlorine residues from your skin and hair.

Human uses of Cl

Remembering from the characteristics of chlorine that it is a “capricious” element (when it comes to interaction with other substances), it will be interesting to know that it is quite often used in industry.

First of all, it is used to disinfect many substances.

Cl is also used in the manufacture of certain types of pesticides, which helps save crops from pests.

The ability of this substance to interact with almost all elements of the periodic table (characteristic of chlorine as a non-metal) helps with its help to extract certain types of metals (Ti, Ta and Nb), as well as lime and hydrochloric acid.

In addition to all of the above, Cl is used in the production of industrial substances (polyvinyl chloride) and medications (chlorhexidine).

It is worth mentioning that today a more effective and safe disinfectant has been found - ozone (O 3). However, it is more expensive to produce than chlorine, and the gas is even more unstable than chlorine ( a brief description of physical properties at 6-7 p.). Therefore, few people can afford to use ozonation instead of chlorination.

How is chlorine produced?

Today, many methods are known for the synthesis of this substance. They all fall into two categories:

• Chemical.
• Electrochemical.

In the first case, Cl is obtained due to a chemical reaction. However, in practice they are very costly and ineffective.

Therefore, industry prefers electrochemical methods (electrolysis). There are three of them: diaphragm, membrane and mercury electrolysis.

DEFINITION

Chlorine is in the third period of the VII group of the main (A) subgroup of the Periodic table.

Belongs to elements of the p-family. Non-metal. The nonmetallic elements included in this group are collectively called halogens. Designation - Cl. Serial number - 17. Relative atomic mass- 35.453 a.m.u.

Electronic structure of the chlorine atom

The chlorine atom consists of a positively charged nucleus (+17), consisting of 17 protons and 18 neutrons, around which 17 electrons move in 3 orbits.

Fig.1. Schematic structure of the chlorine atom.

The distribution of electrons among orbitals is as follows:

17Cl) 2) 8) 7 ;

1s 2 2s 2 2p 6 3s 2 3p 5 .

The outer energy level of the chlorine atom contains seven electrons, all of which are considered valence electrons. The energy diagram of the ground state takes the following form:

The presence of one unpaired electron indicates that chlorine is capable of exhibiting the +1 oxidation state. Several excited states are also possible due to the presence of vacant 3 d-orbitals. First, electrons 3 are steamed p-sublevel and occupy free d-orbitals, and then - electrons 3 s-sublevel:

This explains the presence of chlorine in three more oxidation states: +3, +5 and +7.

Examples of problem solving

EXAMPLE 1

Chlorine was probably obtained by alchemists, but its discovery and first research is inextricably linked with the name of the famous Swedish chemist Carl Wilhelm Scheele. Scheele discovered five chemical elements - barium and manganese (together with Johan Hahn), molybdenum, tungsten, chlorine, and independently of other chemists (albeit later) - three more: oxygen, hydrogen and nitrogen. This achievement could not be repeated by any chemist subsequently. At the same time, Scheele, already elected as a member of the Royal Swedish Academy of Sciences, was a simple pharmacist in Köping, although he could have taken a more honorable and prestigious position. Frederick II the Great himself, the Prussian king, offered him the post of professor of chemistry at the University of Berlin. Refusing such tempting offers, Scheele said: “I cannot eat more than I need, and what I earn here in Köping is enough for me to eat.”

Numerous chlorine compounds were known, of course, long before Scheele. This element is part of many salts, including the most famous - table salt. In 1774, Scheele isolated chlorine in free form by heating the black mineral pyrolusite with concentrated hydrochloric acid: MnO 2 + 4HCl ® Cl 2 + MnCl 2 + 2H 2 O.

At first, chemists considered chlorine not as an element, but as a chemical compound of the unknown element muria (from the Latin muria - brine) with oxygen. It was believed that hydrochloric acid(it was called Murian) contains chemically bound oxygen. This was “testified”, in particular, by the following fact: when a chlorine solution stood in the light, oxygen was released from it, and hydrochloric acid remained in the solution. However, numerous attempts to “tear” oxygen from chlorine led nowhere. So, no one managed to obtain carbon dioxide by heating chlorine with coal (which, when high temperatures“takes away” oxygen from many compounds containing it). As a result of similar experiments carried out by Humphry Davy, Joseph Louis Gay-Lussac and Louis Jacques Thenard, it became clear that chlorine does not contain oxygen and is a simple substance. The experiments of Gay-Lussac, who analyzed the quantitative ratio of gases in the reaction of chlorine with hydrogen, led to the same conclusion.

In 1811, Davy proposed the name “chlorin” for the new element - from the Greek. "chloros" - yellow-green. This is exactly the color of chlorine. The same root is in the word “chlorophyll” (from the Greek “chloros” and “phyllon” - leaf). A year later, Gay-Lussac “shortened” the name to “chlorine.” But still the British (and Americans) call this element “chlorine”, while the French call it chlore. The Germans, the “legislators” of chemistry throughout almost the entire 19th century, also adopted the abbreviated name. (in German chlorine is Chlor). In 1811, the German physicist Johann Schweiger proposed the name “halogen” for chlorine (from the Greek “hals” - salt, and “gennao” - give birth). Subsequently, this term was assigned not only to chlorine, but also to all its analogues in the seventh group - fluorine, bromine, iodine, astatine.

The demonstration of hydrogen combustion in a chlorine atmosphere is interesting: sometimes during the experiment an unusual phenomenon occurs by-effect: There is a buzzing sound. Most often, the flame hums when a thin tube through which hydrogen is supplied is lowered into a cone-shaped vessel filled with chlorine; the same is true for spherical flasks, but in cylinders the flame usually does not hum. This phenomenon was called the “singing flame.”

In an aqueous solution, chlorine reacts partially and rather slowly with water; at 25° C, equilibrium: Cl 2 + H 2 O HClO + HCl is established within two days. Hypochlorous acid decomposes in light: HClO ® HCl + O. It is atomic oxygen that is credited with the bleaching effect (absolutely dry chlorine does not have this ability).

Chlorine in its compounds can exhibit all oxidation states - from –1 to +7. With oxygen, chlorine forms a number of oxides, all of them in their pure form are unstable and explosive: Cl 2 O - yellow-orange gas, ClO 2 - yellow gas (below 9.7 o C - bright red liquid), chlorine perchlorate Cl 2 O 4 (ClO –ClO 3, light yellow liquid), Cl 2 O 6 (O 2 Cl–O–ClO 3, bright red liquid), Cl 2 O 7 – colorless, very explosive liquid. At low temperatures unstable oxides Cl 2 O 3 and ClO 3 were obtained. ClO 2 oxide is produced on an industrial scale and is used instead of chlorine to bleach pulp and disinfect drinking water and Wastewater. With other halogens, chlorine forms a number of so-called interhalogen compounds, for example, ClF, ClF 3, ClF 5, BrCl, ICl, ICl 3.

Chlorine and its compounds with a positive oxidation state are strong oxidizing agents. In 1822, the German chemist Leopold Gmelin obtained red salt from yellow blood salt by oxidation with chlorine: 2K 4 + Cl 2 ® K 3 + 2KCl. Chlorine easily oxidizes bromides and chlorides, releasing bromine and iodine in free form.

Chlorine in different oxidation states forms a number of acids: HCl - hydrochloric (hydrochloric, salts - chlorides), HClO - hypochlorous (salts - hypochlorites), HClO 2 - chlorous (salts - chlorites), HClO 3 - hypochlorous (salts - chlorates), HClO 4 – chlorine (salts – perchlorates). Of the oxygen acids, only perchloric acid is stable in its pure form. Of the salts of oxygen acids, hypochlorites are used in practical use, sodium chlorite NaClO 2 - for bleaching fabrics, for the manufacture of compact pyrotechnic oxygen sources (“oxygen candles”), potassium chlorates (Bertholometa salt), calcium and magnesium (for pest control Agriculture, as components of pyrotechnic compositions and explosives, in the production of matches), perchlorates - components of explosives and pyrotechnic compositions; Ammonium perchlorate is a component of solid rocket fuels.

Chlorine reacts with many organic compounds. It quickly attaches to unsaturated compounds with double and triple carbon-carbon bonds (the reaction with acetylene proceeds explosively), and in the light to benzene. Under certain conditions, chlorine can replace hydrogen atoms in organic compounds: R–H + Cl 2 ® RCl + HCl. This reaction played a significant role in the history of organic chemistry. In the 1840s, the French chemist Jean Baptiste Dumas discovered that when chlorine reacts with acetic acid, the reaction occurs with amazing ease

CH 3 COOH + Cl 2 ® CH 2 ClCOOH + HCl. With an excess of chlorine, trichloroacetic acid CCl 3 COOH is formed. However, many chemists were distrustful of Dumas' work. Indeed, according to the then generally accepted theory of Berzelius, positively charged hydrogen atoms could not be replaced by negatively charged chlorine atoms. This opinion was held at that time by many outstanding chemists, among whom were Friedrich Wöhler, Justus Liebig and, of course, Berzelius himself.

To ridicule Dumas, Wöhler handed over to his friend Liebig an article on behalf of a certain S. Windler (Schwindler - in German a fraudster) about a new successful application of the reaction allegedly discovered by Dumas. In the article, Wöhler wrote with obvious mockery about how in manganese acetate Mn(CH 3 COO) 2 it was possible to replace all the elements, according to their valence, with chlorine, resulting in a yellow crystalline substance consisting of only chlorine. It was further said that in England, by successively replacing all atoms in organic compounds with chlorine atoms, ordinary fabrics are converted into chlorine ones, and that at the same time things retain their appearance. In a footnote it was stated that London shops were selling a brisk trade in material consisting of chlorine alone, as this material was very good for nightcaps and warm underpants.

The reaction of chlorine with organic compounds leads to the formation of many organochlorine products, among which are the widely used solvents methylene chloride CH 2 Cl 2, chloroform CHCl 3, carbon tetrachloride CCl 4, trichlorethylene CHCl=CCl 2, tetrachlorethylene C 2 Cl 4. In the presence of moisture, chlorine discolors the green leaves of plants and many dyes. This was used back in the 18th century. for bleaching fabrics.

Chlorine as a poisonous gas.

Scheele, who received chlorine, noted a very unpleasant strong odor, difficulty breathing and coughing. As we later found out, a person smells chlorine even if one liter of air contains only 0.005 mg of this gas, and at the same time it already has an irritating effect on the respiratory tract, destroying the cells of the mucous membrane of the respiratory tract and lungs. A concentration of 0.012 mg/l is difficult to tolerate; if the concentration of chlorine exceeds 0.1 mg/l, it becomes life-threatening: breathing quickens, becomes convulsive, and then becomes increasingly rare, and after 5–25 minutes breathing stops. Maximum permissible in air industrial enterprises the concentration is considered to be 0.001 mg/l, and in the air of residential areas - 0.00003 mg/l.

St. Petersburg academician Toviy Egorovich Lovitz, repeating Scheele's experiment in 1790, accidentally released a significant amount of chlorine into the air. After inhaling it, he lost consciousness and fell, then suffered excruciating chest pain for eight days. Fortunately, he recovered. The famous English chemist Davy almost died from chlorine poisoning. Experiments with even small amounts of chlorine are dangerous, as they can cause severe lung damage. They say that the German chemist Egon Wiberg began one of his lectures on chlorine with the words: “Chlorine is a poisonous gas. If I get poisoned during the next demonstration, please take me out into the fresh air. But, unfortunately, the lecture will have to be interrupted.” If you release a lot of chlorine into the air, it becomes a real disaster. This was experienced by the Anglo-French troops during the First World War. On the morning of April 22, 1915, the German command decided to carry out the first gas attack in the history of wars: when the wind blew towards the enemy, on a small six-kilometer section of the front near the Belgian town of Ypres, the valves of 5,730 cylinders were simultaneously opened, each containing 30 kg of liquid chlorine. Within 5 minutes, a huge yellow-green cloud formed, which slowly moved away from the German trenches towards the Allies. The English and French soldiers were completely defenseless. The gas penetrated through the cracks into all the shelters; there was no escape from it: after all, the gas mask had not yet been invented. As a result, 15 thousand people were poisoned, 5 thousand of them to death. A month later, on May 31, the Germans repeated the gas attack on the eastern front - against Russian troops. This happened in Poland near the city of Bolimova. At the 12 km front, 264 tons of a mixture of chlorine and much more toxic phosgene (carbonic acid chloride COCl 2) were released from 12 thousand cylinders. The tsarist command knew about what happened at Ypres, and yet the Russian soldiers had no means of defense! As a result of the gas attack, the losses amounted to 9,146 people, of which only 108 were as a result of rifle and artillery shelling, the rest were poisoned. At the same time, 1,183 people died almost immediately.

Soon, chemists showed how to escape from chlorine: you need to breathe through a gauze bandage soaked in a solution of sodium thiosulfate (this substance is used in photography, it is often called hyposulfite). Chlorine reacts very quickly with a thiosulfate solution, oxidizing it:

Na 2 S 2 O 3 + 4Cl 2 + 5H 2 O ® 2H 2 SO 4 + 2NaCl + 6HCl. Of course, sulfuric acid is also not a harmless substance, but its diluted aqueous solution is much less dangerous than poisonous chlorine. Therefore, in those years, thiosulfate had another name - “antichlor”, but the first thiosulfate gas masks were not very effective.

In 1916, the Russian chemist and future academician Nikolai Dmitrievich Zelinsky invented a truly effective gas mask, in which toxic substances were retained by a layer of activated carbon. Such coal with a very developed surface could retain significantly more chlorine than gauze soaked in hyposulfite. Fortunately, the “chlorine attacks” remained only a tragic episode in history. After the World War, chlorine had only peaceful professions left.

Use of chlorine.

Every year, huge amounts of chlorine are produced worldwide – tens of millions of tons. Only in the USA by the end of the 20th century. About 12 million tons of chlorine were produced annually by electrolysis (10th place among chemical production). The bulk of it (up to 50%) is spent on the chlorination of organic compounds - to produce solvents, synthetic rubber, polyvinyl chloride and other plastics, chloroprene rubber, pesticides, medicines, many other necessary and healthy products. The rest is consumed for the synthesis of inorganic chlorides, in the pulp and paper industry for bleaching wood pulp, and for water purification. Chlorine is used in relatively small quantities in the metallurgical industry. With its help, very pure metals are obtained - titanium, tin, tantalum, niobium. By burning hydrogen in chlorine, hydrogen chloride is obtained, and from it hydrochloric acid is obtained. Chlorine is also used for the production of bleaching agents (hypochlorites, bleach) and water disinfection by chlorination.

Ilya Leenson

• Designation - Cl (Chlorum);
• Period - III;
• Group - 17 (VIIa);
• Atomic mass - 35.4527;
• Atomic number - 17;
• Atomic radius = 99 pm;
• Covalent radius = 102±4 pm;
• Electron distribution - 1s 2 2s 2 2p 6 3s 2 3p 5 ;
• melting temperature = 100.95°C;
• boiling point = -34.55°C;
• Electronegativity (according to Pauling/according to Alpred and Rochow) = 3.16/-;
• Oxidation state: +7, +6, +5, +4, +3, +1, 0, -1;
• Density (no.) = 3.21 g/cm3;
• Molar volume = 18.7 cm 3 /mol.

Chlorine in its pure form was first isolated by the Swedish scientist Carl Scheele in 1774. The element received its current name in 1811, when G. Davy proposed the name “chlorine,” which was soon shortened to “chlorine” by J. Gay-Lussac. The German scientist Johann Schweiger proposed the name “halogen” for chlorine, but it was decided to use this term to name the entire group of elements, which includes chlorine.

Chlorine is the most common halogen in the earth's crust - chlorine accounts for 0.025% of the total mass of atoms in the earth's crust. Due to its high activity, chlorine does not occur in nature in free form, but only as part of compounds, and chlorine “doesn’t care” which element it reacts with, modern science Chlorine compounds are known from almost the entire periodic table.

The bulk of chlorine on Earth is contained in the salty water of the World Ocean (content 19 g/l). Of the minerals, the most chlorine is contained in halite, sylvite, sylvinite, bischofite, carnallite, and kainite.

Chlorine plays an important role in the activity of nerve cells, as well as in the regulation of osmotic processes occurring in the body of humans and animals. Chlorine is also part of the green substance in plants - chlorophyll.

Natural chlorine consists of a mixture of two isotopes:

• 35 Cl - 75.5%
• 37 Cl - 24.5%

Rice. Structure of the chlorine atom.

The electronic configuration of the chlorine atom is 1s 2 2s 2 2p 6 3s 2 3p 5 (see Electronic structure of atoms). 5 electrons located in the outer 3p level + 2 electrons of the 3s level (7 electrons in total) can participate in the formation of chemical bonds with other elements; therefore, in compounds, chlorine can take oxidation states from +7 to -1. As mentioned above, chlorine is a reactive halogen.

Physical properties of chlorine:

• at no. chlorine is a poisonous gas of yellow-green color with a pungent odor;
• chlorine is 2.5 times heavier than air;
• at no. 2.5 volumes of chlorine are dissolved in 1 liter of water - this solution is called chlorine water.

Chemical properties of chlorine

Interaction of chlorine with simple substances(Cl acts as a strong oxidizing agent):

• with hydrogen (the reaction occurs only in the presence of light): Cl 2 +H 2 = 2HCl
• with metals to form chlorides: Cl 2 0 +2Na 0 = 2Na +1 Cl -1 3Cl 2 0 +2Fe 0 = 2Fe +3 Cl 3 -1
• with nonmetals less electronegative than chlorine: Cl 2 0 +S 0 = S +2 Cl 2 -1 3Cl 2 0 +2P 0 = 2P +3 Cl 3 -1
• Chlorine does not react directly with nitrogen and oxygen.

Interaction of chlorine with complex substances:

One of the most famous reactions of chlorine with complex substances is the interaction of chlorine with water - who lives in big city, probably periodically encounters a situation when, having opened a water tap, they smell a persistent smell of chlorine, after which many complain, they say, the water has been chlorinated again. Chlorination of water is one of the main ways to disinfect it from unwanted microorganisms that are unsafe for human health. Why is this happening? Let us analyze the reaction of chlorine with water, which occurs in two stages:

• At the first stage, two acids are formed: hydrochloric and hypochlorous: Cl 2 0 +H 2 O ↔ HCl -1 +HCl +1 O
• At the second stage, hypochlorous acid decomposes with the release of atomic oxygen, which oxidizes the water (killing microorganisms) + exposes fabrics dyed with organic dyes to a bleaching effect if they are immersed in chlorine water: HClO = HCl+[O] - the reaction occurs in the light

WITH acids chlorine does not react.

Interaction of chlorine with reasons:

• in the cold: Cl 2 0 +2NaOH = NaCl -1 +NaCl +1 O+H 2 O
• when heated: 3Cl 2 0 +6KOH = 5KCl -1 +KCl +5 O 3 +3H 2 O
• with metal bromides: Cl 3 +2KBr = 2KCl+Br 2 ↓
• with metal iodides: Cl 2 +2KI = 2KCl+I 2 ↓
• Chlorine does not react with metal fluorides due to their higher oxidizing ability than chlorine.

Chlorine readily reacts with organic substances:

Cl 2 +CH 4 → CH 3 Cl+HCl Cl 2 +C 6 H 6 → C 6 H 5 Cl+HCl

As a result of the first reaction with methane, which occurs in the light, methyl chloride and hydrochloric acid are formed. As a result of the second reaction with benzene, which occurs in the presence of a catalyst (AlCl 3), chlorobenzene and hydrochloric acid are formed.

• Equations of redox reactions of chlorine (electronic balance method).
• Equations of redox reactions of chlorine (half-reaction method).

Production and use of chlorine

Industrially, chlorine is produced by electrolysis of an aqueous solution (chlorine is released at the anode; hydrogen is released at the cathode) or molten sodium chloride (chlorine is released at the anode; sodium is released at the cathode):

2NaCl+2H 2 O → Cl 2 +H 2 +2NaOH 2NaCl → Cl 2 +2Na

In the laboratory, chlorine is produced by the action of concentrated HCl on various oxidizing agents when heated. Manganese oxide, potassium permanganate, and Berthollet salt can act as oxidizing agents:

4HCl -1 +Mn +4 O 2 = Mn +2 Cl 2 +Cl 2 0 +2H 2 O 2KMn +7 O 4 +16HCl -1 = 2KCl+2Mn +2 Cl 2 +5Cl 2 0 +8H 2 O KCl + 5 O 3 +6HCl -1 = KCl+3Cl 2 0 +3H 2 O

Application of chlorine:

• bleaching fabrics and paper;
• water disinfection;
• plastics production;
• production of bleach, chloroform, pesticides, detergents, rubbers;
• synthesis of hydrogen chloride in the production of hydrochloric acid.