Let us know what is cl2 molar mass. No matter how negatively we treat public toilets, nature dictates its own rules, and we have to visit them. In addition to the natural (for a given space) smell, another familiar fragrance is bleach, which is used to disinfect a room. It got its name because of the main active ingredient in it – Cl. Let us learn about this chemical element and its properties, as well as characterize chlorine according to its position in the periodic table. ( Cl2 Molar Mass)
How was this item discovered?
The chlorine-containing compound (HCl) was first synthesized in 1772 by the British priest Joseph Priestley.
After 2 years, his Swedish colleague Carl Scheele was able to describe a method for the isolation of Cl using the reaction between hydrochloric acid and manganese dioxide. However, this chemist did not understand that a new chemical element was being synthesized as a result.
It took almost 40 years for scientists to learn how to remove chlorine in practice. It was first performed in 1811 by Briton Humphrey Davy. In doing so, he used a different reaction than his theoretical predecessors. Davy, using electrolysis, decomposed NaCl (known as kitchen salt) into its components.
After studying the resulting substance, the British chemist realized that it was elementary. After this discovery, Davy not only named it – chlorine (chlorine), but was also able to characterize chlorine, although it was very primitive.
Thanks to Joseph Gay-Lussak, chlorine was transformed into chlorine and in this form exists today in French, German, Russian, Belarusian, Ukrainian, Czech, Bulgarian and some other languages. The name “chlorine” is used to this day in English, and in Italian and Spanish “chloro”. ( Cl2 Molar Mass)
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 knowing more about it.
The name chlorine was derived from the Greek word (green). It was given because of the yellow-green color of this substance.
Chlorine exists freely as a diatomic gas Cl 2, but it practically does not occur in this form in nature. More often it appears in various compounds.
In addition to its characteristic shade, chlorine has a sweet pungent odor. It is a very toxic substance, therefore, if it gets into the air and is inhaled by a person or animal, it can cause their death within a few minutes (depending on the concentration of Cl). .
Since chlorine is about 2.5 times heavier than air, it will always be below it, that is, near the ground. For this reason, if you suspect the presence of Cl, you should climb as high as possible, as there will be a low concentration of this gas.
In addition, unlike some other toxic substances, chlorine-containing substances have a characteristic color, which can allow them to be visually recognized and acted upon. Most standard gas masks help protect the respiratory tract and mucous membranes from Cl damage. However, for complete protection, you need to take more serious measures to neutralize the toxic substance.
It should be noted that it was with the use of chlorine as a poisonous gas by the Germans in 1915 that chemical weapons began their history. As a result of the use of about 200 tons of the substance, 15 thousand people were poisoned in a matter of minutes. A third of them died almost immediately, a third suffered permanent damage and only 5 thousand survived.
Such a dangerous substance is still not banned and is produced annually in millions of tons? It’s all about its special properties, and in order to understand them, it is worth considering the features of chlorine. The easiest way to do this is to use the periodic table.
chlorine as halogen
In addition to extreme toxicity and a pungent odor (typical of all representatives of this group), Cl is highly soluble in water. Practical proof of this is the addition of chlorine-based detergents to pool water. ( Cl2 Molar Mass)
When exposed to moist air, the substance in question begins to smoke.
Cl properties as non-metals
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 a catalyst to carry out the reactions. This role can be played by H2O.
Reactions with Cl are often endothermic (they absorb heat).
It should be noted that chlorine in crystalline form (in powder form) 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, oxides that form are very unstable and prone to decomposition. In them, the Cl oxidation state can manifest itself from +1 to +7.
When interacting with F, fluoride is formed. Their oxidation state may be different. ( Cl2 Molar Mass)
Chlorine: Characterization of a substance in terms of its physical properties
In addition to chemical properties, the element in question also has physical properties. ( Cl2 Molar Mass)
Effect of temperature on the state of aggregation Cl
Having considered the physical characteristics of the element chlorine, we understand that it is able to pass into various states of aggregation. It all depends on the temperature regime.
Cl is generally a highly corrosive gas. However, it can liquefy easily. It is affected by temperature and pressure. For example, if it is 8 atmospheres, and the temperature is +20 ° C, then Cl 2 is an acid-yellow liquid. If this pressure is increasing continuously it is able to maintain the state of aggregation up to +143 degrees.
Upon reaching -32 °C, the state of chlorine ceases to depend on pressure, and it remains a liquid.
Crystallization of matter (solid state) occurs at -101 degrees.
where Cl is present in nature
Having considered the general characteristics of 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 (therefore, at the beginning of the study of this element by scientists, it took years to learn how to synthesize it). Usually Cl is contained in compounds in various minerals: confectionery, sylvite, kenite, biscophyte, etc.
Most commonly, it is found in salts extracted from sea or ocean water.
effect on body
When considering the characteristics of chlorine, it has already been said more than once that it is extremely toxic. At the same time, atoms of a substance are contained not only in minerals, but also in almost all organisms from plants to humans.
Due to special properties, ClO ions penetrate through cell membranes better than others (therefore, more than 80% of all chlorine in the human body is in the intercellular space).
Together with K, Cl is responsible for the regulation of the water-salt balance, and, consequently, for the osmotic affinity. ( Cl2 Molar Mass)
Despite such an important role in the body, in its pure form, Cl 2 kills all living things – from cells to whole organisms. However, in controlled doses and with short-term exposure, it does not have time to harm.
Any swimming pool is a prime example of this last statement. As you know, the water in such institutions is sterile. Moreover, if a person rarely visits such an institution (once a week or 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 are in the water almost all day (lifeguards, trainers), often suffer from skin diseases or have weakened immunity.
In this regard, after visiting the pool, you should definitely take a shower – in order to wash off possible chlorine residues from the skin and hair.
Human use of Cl
Considering the characteristics of chlorine that it is a “capricious” element (when it comes to interaction with other substances), it would be interesting to know that it is often used in industry.
Firstly, it is used to disinfect many substances.
Cl is also used in the manufacture of some types of insecticides, which help protect crops from pests.
The ability of this substance to interact with almost all elements of the periodic table (characterizing chlorine as a non-metal) helps to remove some types of metals (Ti, Ta and Nb), as well as lime and hydrochloric acid. ( Cl2 Molar Mass)
In addition to all of the above, Cl is used in the production of industrial substances (polyvinyl chloride) and medicines (chlorhexidine).
It is noteworthy that today a more effective and safe disinfectant has been found – ozone (O3). However, it is more expensive to produce than chlorine, and the gas is also more volatile than chlorine (a brief description of physical properties in 6–7 p.). Therefore, only a few can use ozonation instead of chlorination.
How is chlorine obtained?
Today, several methods are known for the synthesis of this substance. They all fall into two categories:
In the first case, Cl is produced by a chemical reaction. However, in practice they are very expensive and inefficient.
Therefore, the industry prefers electrochemical methods (electrolysis). There are three of them: diaphragm, membrane and mercury electrolysis.Ion radius (+ 7e) 27 (-1e) 181 pm
Electronegativity (according to Pauling) 3.16 Electrode potential 0 Oxidation state 7, 6, 5, 4, 3, 1, −1 Thermodynamic properties of a simple substance Density (− at 33.6 °C) 1.56
/cm/molar heat capacity 21.838 J/(mol) thermal conductivity 0.009 W/(() melting temperature 172.2 heat of fusion 6.41 kJ/mol boiling temperature 238.6 heat of vaporization 20.41 kJ/mol molar volume 18.7 cm / mol Crystal lattice lattice structure of a simple substance orthorhombic lattice parameter a \u003d 6.29 b \u003d 4.50 c \u003d 8.21 c / a ratio — goodbye temperature n / a
Chlorine ( – green ) – an element of the main subgroup of the seventh group, D. I. The third period of Mendeleev’s periodic system of chemical elements, with atomic number 17. It is designated by the symbol Cl (Latin chlorum). reactive non-metals. It is included in the group of halogens (originally the name “halogen” was used by the German chemist Schweiger for chlorine [literally translated as “halogen” in the singular form]), but it did not take root, and the latter is common to the VII group of elements, which also includes chlorine).
Under normal conditions the simple substance chlorine (CAS number: 7782-50-5) is a poisonous gas of yellow-green color with a pungent odor. The chlorine molecule is diatomic (formula Cl 2 ). ( Cl2 Molar Mass)
chlorine atomic diagram
Chlorine was first obtained in 1772 by Scheele, who described its release during the interaction of pyrolusite with hydrochloric acid in his treatise on pyrolusite:
4HCl + MnO 2 \u003d Cl 2 + MnCl 2 + 2H 2 O
Scheel noted the odor of chlorine, similar to the smell of aqua regia, its ability to interact with gold and cinnabar, and its bleaching properties.
However, Scheele, according to the phlogiston theory prevalent in chemistry at the time, suggested that chlorine was refined hydrochloric acid, i.e. hydrochloric acid oxide. Berthollet and Lavoisier suggested that chlorine is an oxide of the element murine, but attempts to isolate it were unsuccessful until the work of Davy, who was able to decompose table salt into sodium and chlorine by electrolysis.
distribution in nature
In nature, there are two isotopes of chlorine 35Cl and 37Cl. Chlorine is the most abundant halogen in the earth’s crust. Chlorine is very active – it combines directly with almost all the elements of the periodic table. Therefore, in nature, it occurs only in the form of compounds in the composition of minerals: halite NaCl, sylvite KCl, sylvinite KCl NaCl, biscophyte MgCl 2 6H2O, carnallite CCl MgCl 2 6H 2 O, kainite KCl MgSO 4 3H 2 O. Seas And the largest reserves of chlorine are found in the composition of the salts of the waters of the oceans. ( Cl2 Molar Mass)
Chlorine accounts for 0.025% of the total number of atoms in the Earth’s crust, the Clarke number of chlorine is 0.19%, and the human body consists of 0.25% chlorine ions by weight. In humans and animals, chlorine is found mainly in intercellular fluids (including blood) and plays an important role in the regulation of osmotic processes, as well as in processes associated with the work of nerve cells.
In nature, there are 2 stable chlorine isotopes: with a large number of 35 and 37. The ratio of their content is equal to 75.78% and 24.22%, respectively.
|ISOTOPE||RELATIVE, EMU||HALF LIFE||DECAY TYPE||NUCLEAR SPIN|
|36 cl||35.9683069||301,000 years||.-decay in 36 ar||0|
|38 cl||37.9680106||37.2 minutes||.-decay in 38 Ar||2|
|39 cl||38.968009||55.6 minutes||.-39 er in decay||3/2|
|40 cl||39.97042||1.38 minutes||.-decay in 40 r||2|
|41 cl||40.9707||34 s||.-41 Decay in Ar|
|42 cl||41.9732||46.8 s||.-decay in 42 ar|
|43 cl||42.9742||3.3 s||.-43 Decay in Decay|
physical and physico-chemical properties
Under normal conditions, chlorine is a yellowish-green gas with a suffocating odor. Some of its physical properties are presented in the table.
Some physical properties of chlorine
|boiling temperature||−34 °C|
|melting temperature||C101 ° C|
|temperature of decomposition|
(separation into atoms)
|~ 1400 ° C|
|Density (Gas, no)||3.214 g/l|
|electron affinity of an atom||3.65 EV|
|first ionization energy||12.97 EV|
|Heating Capacity (298 K, Gas)||34.94 (J / mol K)|
|critical temperature||from 144 °|
|severe pressure||76 ATM|
|Standard enthalpy formation (298 K, gas)||0 (kJ/mol)|
|Standard Entropy of Formation (298 K, Gas)||222.9 (J / mol K)|
|melting enteritis||6.406 (kJ/mol)|
|Boiling Thalpi||20.41 (kJ/mol)|
Upon cooling, chlorine turns into a liquid at a temperature of about 239 K, and then crystallizes in an orthorhombic lattice with a space group below 113 K CMCA and parameters a \u003d 6.29 b \u003d 4.50, c \u003d 8.21. Below 100 K, the orthorhombic modification of crystalline chlorine turns into a tetragonal, with a space group p 4 2 / ncm and lattice parameters a \u003d 8.56 and c \u003d 6.12.
|Water (0 °C)||1,48|
|Water (20 °C)||0,96|
|Water (25 °C)||0,65|
|Water (40 °C)||0,46|
|Water (60 °C)||0,38|
|Water (80 °C)||0,22|
|Tetrachloromethane (0 C)||31,4|
|Tetrachloromethane (19 °C)||17,61|
|Tetrachloromethane (40 °C)||11|
|chloroform||let’s break up well|
|TiCl 4, SiCl 4, SnCl 4||breach|
When exposed to light or heating, it actively (sometimes with explosion) reacts with hydrogen by a radical mechanism. The chlorine-hydrogen mixture contains 5.8 to 88.3% hydrogen which is released upon irradiation with the formation of hydrogen chloride. A mixture of chlorine and hydrogen in small concentrations burns with a colorless or yellow-green flame. Maximum temperature of hydrogen-chlorine flame 2200 °C:
Cl 2 + H 2 → 2HCl 5Cl 2 + 2P → 2PCl 5 2S + Cl 2 → S 2 Cl 2 Cl 2 + 3F 2 (g) → 2ClF 3
Cl 2 + CO → COCl 2
When dissolved in water or alkali, chlorine decomposes, forming hypochlorous (and perchloric when heated) and hydrochloric acid, or their salts:
Cl 2 + H 2 O → HCl + HClO 3Cl 2 + 6NaOH → 5NaCl + NaClO 3 + 3H 2 O Cl 2 + Ca (OH) 2 → CaCl (OCl) + H 2 O 4HH 3 + 3Cl 2 → NCl 3 + 3NH 4 सीएल
Chlorine Oxidizing Properties
Cl 2 + H 2 S → 2HCl + S
reactions with organic matter
CH 3 -CH 3 + Cl 2 → C 2 H 6-x Cl x + HCl
Connects unsaturated compounds by multiple bonds:
CH 2 \u003d CH 2 + Cl 2 → Cl-CH 2 -CH 2 -Cl
Aromatic compounds replace the hydrogen atom with chlorine in the presence of catalytic compounds (for example, AlCl 3 or FeCl 3):
C 6 H 6 + Cl 2 → C 6 H 5 Cl + HCl
Chlorine Chlorine Production Methods
Initially, the industrial method of producing chlorine was based on the Scheele method, namely the reaction of pyrolusite with hydrochloric acid: ( Cl2 Molar Mass)
MnO 2 + 4HCl → MnCl 2 + Cl 2 + 2H 2 O 2NaCl + 2H 2 O → H 2 + Cl 2 + 2NaOH Anode: 2Cl – – 2е – → Cl 2 0 Cathode: 2H 2 O + 2e – → H 2 + 2OH –
Since the electrolysis of water is running parallel to the electrolysis of sodium chloride, the total equation can be expressed as:
1.80 NaCl + 0.50 H 2 O → 1.00 Cl 2 + 1.10 NaOH + 0.03 H 2
Three variants of the electrochemical method are used for chlorine production. Two of them are solid cathode electrolysis: diaphragm and membrane methods, the third is liquid cathode electrolysis (mercury production method). Among power generation methods, the easiest and most convenient method is electrolysis with a mercury cathode, but this method causes significant damage to the environment through evaporation and leakage of metallic mercury.
solid cathode diaphragm method
The cavity of the electrolyzer is divided by a porous mica partition—a diaphragm—into the cathode and anode space, where the electrolyzer’s cathode and anode are located, respectively. Therefore, such electrolyzers are often called diaphragm electrolysis, and the production method is called diaphragm electrolysis. A stream of saturated anolyte (NaCl solution) is continuously fed into the anode space of the diaphragm cell. As a result of the electrochemical process, chlorine is released at the anode due to the decomposition of chlorine, and hydrogen is released at the cathode due to the decomposition of water. In this case, the cathode region is enriched with sodium hydroxide.
solid cathode membrane method
The membrane method is essentially the same as the diaphragm method, but the anode and cathode spaces are separated by a cation-exchange polymeric membrane. Membrane production is more efficient than diaphragms, but more difficult to use.
mercury liquid cathode method
The process is carried out in an electrolytic bath, which consists of an electrolyzer, decomposer and mercury pump, which are interconnected by circulators. In an electrolytic bath, mercury circulates under the action of a mercury pump, passing through the electrolyzer and decomposer. The cathode of the electrolyzer is a stream of mercury. Anodes – graphite or low wear. Together with mercury, an anolytic stream – sodium chloride solution continuously flows through the electrolyzer. As a result of the electrochemical decomposition of chloride, chlorine molecules are formed at the anode, and at the cathode, the released sodium dissolves in mercury, forming an amalgam. ( Cl2 Molar Mass)
In laboratories for the production of chlorine, processes are commonly used based on the oxidation of hydrogen chloride with strong oxidants (eg, manganese(IV) oxide, potassium permanganate, potassium dichromate): ( Cl2 Molar Mass)
2KMnO 4 + 16HCl → 2KCl + 2MnCl 2 + 5Cl 2 + 8H 2 O K 2 Cr 2 O 7 + 14HCl → 3Cl 2 + 2KCl + 2CrCl 3 + 7H 2 O
storage of chlorine
The chlorine produced is stored in special “tanks” or pumped into high-pressure steel cylinders. Cylinders containing liquid chlorine under pressure have a special color – swamp color. It should be noted that during prolonged operation of chlorine cylinders, highly explosive nitrogen trichloride accumulates in them, and therefore, from time to time chlorine cylinders should undergo regular flushing and purification of nitrogen chloride.
chlorine quality standards
According to GOST 6718-93 “Liquid chlorine. Specifications “The following grades of chlorine are used to produce
Chlorine is used in many industries, science and household needs:
- In the production of polyvinyl chloride, plastic compounds, synthetic rubber from which they are made: wires, window profiles, packaging materials, clothing and footwear, linoleum and gramophone records, varnishes, instruments and polystyrene, toys, instrument parts, building materials For insulation. Polyvinyl chloride is produced by polymerizing vinyl chloride, which today is mostly obtained by the chlorine-balanced method from ethylene via the intermediate 1,2-dichloroethane.
- The bleaching properties of chlorine have long been known, although it is not chlorine itself that “bleachs”, but atomic oxygen, which is formed during the decomposition of hypochlorous acid: Cl 2 + H 2 O / HCl + HClO → 2HCl + O .. This method of bleaching fabric, paper, cardboard has been used for many centuries.
- Production of organochlorine insecticides – substances that kill pests that are harmful to crops, but are safe for plants. A significant portion of the chlorine produced is consumed to obtain plant protection products. One of the most important insecticides is hexachlorocyclohexane (often called hexachloran). This substance was first synthesized by Faraday back in 1825, but was found practically only after more than 100 years – in the 30s of our century.
- It was used as a chemical warfare agent, as well as for the production of other chemical warfare agents: mustard gas, phosgene.
- For water disinfection – “chlorination”. The most common method of disinfecting drinking water; Depending on the ability of free chlorine and its compounds to inhibit the enzyme systems of microorganisms that catalyze redox processes. To disinfect drinking water, use: chlorine, chlorine dioxide, chloramine and bleach. SanPiN 22.214.171.1244-01 Centralized water supply establishes the following limits (corridors) of the permissible content of free residual chlorine in drinking water of 0.3 – 0.5 mg / l. Many scientists and even politicians in Russia criticize the very concept of chlorination of tap water, but they cannot offer an alternative to disinfection of chlorine compounds. The materials from which water pipes are made interact with chlorinated tap water in different ways. Free in tap water Duty chlorine significantly reduces the service life of polyolefin-based pipelines: Various types of polyethylene pipes, including cross-linked polyethylene, known as PEX (PE-X). In the USA, to control the penetration of pipelines made of polymeric materials for use in water pipelines with chlorinated water, they had to adopt 3 standards: ASTM F 2023 for Pipes, Membranes and Skeletal Muscles. These channels perform important functions in the regulation of fluid volume, transepithelial transport of ions and stabilization of membrane potential, and are involved in maintaining cell pH. Chlorine accumulates in visceral tissue, skin and skeletal muscles. Chlorine is mainly absorbed in the large intestine. Chlorine absorption and excretion are closely related to sodium ions and bicarbonate, To a lesser extent with mineralocorticoids and the activity of Na + / K + – ATP-ase. Cells accumulate 10-15% of all chlorine, from 1/3 to 1/2 of this amount – in erythrocytes. About 85% of chlorine is found in outer space. Chlorine is excreted from the body mainly through urine (90–95%), feces (4–8%) and through the skin (up to 2%). Chlorine excretion is associated with sodium and potassium ions, and mutually with HCO 3 – (acid-base balance). A person consumes 5-10 grams of NaCl per day.The minimum human requirement for chlorine is about 800 mg per day. The infant receives the required amount of chlorine through breast milk, which contains 11 mmol/L of chlorine. NaCl is essential for the production of hydrochloric acid in the stomach, which aids in digestion and eliminates harmful bacteria. Currently, the involvement of chlorine in the occurrence of certain diseases in humans is not well understood, mainly due to the small number of studies. Suffice it to say that even recommendations for the daily consumption of chlorine have not been developed. Human muscle tissue contains 0.20-0.52% chlorine, bone – 0.09%; In the blood – 2.89 g / l. In the body of an average person (body weight 70 kg) 95 grams of chlorine. Every day a person receives 3-6 grams of chlorine with food, which additionally covers the need for this element. ( Cl2 Molar Mass)
Chlorine ions are important for plants. Chlorine participates in energy metabolism in plants, activates oxidative phosphorylation. It is necessary for the formation of oxygen during photosynthesis by isolated chloroplasts, stimulates the auxiliary processes of photosynthesis, mainly those associated with the accumulation of energy. Chlorine has a positive effect on the absorption of oxygen by the roots, potassium, calcium, magnesium compounds. The excessive concentration of chlorine ions in plants can also have a negative side, for example, reducing the content of chlorophyll, reducing the activity of photosynthesis, and the precipitant chlorine retards the growth and development of plants). Chlorine was one of the first chemical toxins ( Cl2 Molar Mass)
– Especially with the help of analytical laboratory equipment, laboratory and industrial electrodes: reference electrodes ESr-10101 analyze the content of Cl– and K +.
Chlorine requests, we are found by chlorine requests
Interaction, Toxicity, Water, Reactions and Production of Chlorine
- Oxidation state
Chlorine (lat. Chlorum), Cl, group VII of the periodic system of the chemical element MIIeleev, atomic number 17, atomic mass 35.453; Belongs to the halogen family. Under normal conditions (0 °C, 0.1 MN / m 2, or 1 kgf / cm 2) a sharply burning yellow-green gas. Natural chlorine has two stable isotopes: 35 Cl (75.77%) and 37 Cl (24.23%). Radioactive isotopes with mass numbers 31–47 have been obtained artificially, specifically: 32, 33, 34, 36, 38, 39, 40 with half-lives (T ), respectively, 0.31; 2.5; 1.56 seconds; 3.1 10 5 years; 37.3, 55.5 and 1.4 min. 36Cl and 38Cl are used as isotopic indicators.
historical context. Chlorine was first described in 1774 by K. Scheele obtained pyrrolesite by the interaction of hydrochloric acid with MoO 2. However, only in 1810 G. Davy established that chlorine is an element and named it chlorine (from the Greek chloro – yellow-green). In 1813 J. L. Gay-Lussac proposed the name chlorine for this element. ( Cl2 Molar Mass)
Distribution of chlorine in nature.Chlorine is found in nature only in the form of compounds. The average content of chlorine in the earth’s crust (clark) is 2.4 10 -2 by weight in acidic igneous rocks – granites and others, 1.7 10 -2% by weight in basic and ultrastructural 5 10 -3. Water migration plays a major role in the history of chlorine in the Earth’s crust. In the form of Cl ion – it is found in the World Ocean (1.93%), underground brine and salt lakes. The number of its own minerals (mainly natural chlorides) is 97, of which the main half is NaCl (rock salt). Large amounts of potassium and magnesium chlorides and mixed chlorides are also known: sylvinite KCl, sylvinite (Na, K) Cl, carnallite KCl MgCl 2 6H 2 O, kainite KCl MOCSO 4 3H 2 O, bischofite MgCl 2 6H 2 OO Earth In the U.S. history, the influx of HCl contained in volcanic gases into the upper parts of the Earth’s crust was of great importance. ( Cl2 Molar Mass)
Physical properties of chlorine.The boiling point of chlorine is -34.05 °C, the melting point of -101 °C. The density of gaseous chlorine under normal conditions is 3.214 g / l; saturated steam at 0 ° C 12.21 g / l; liquid chlorine at a boiling point of 1.557 g / cm3; At solid chlorine – 102 ° C 1.9 g / cm 3. The vapor pressure of chlorine at 0 °C is 0.369; at 25 °C 0.772; 100 ° C 3.814 MN / m 2 or 3.69, respectively; 7.72; 38.14 kg / cm 2. heat of fusion 90.3 kJ/kg (21.5 cal/g); heat of vaporization 288 kJ / kg (68.8 cal / g); The heat capacity of a gas at a constant pressure of 0.48 kJ / (kg K). Chlorine critical constant: temperature 144 ° C, pressure 7.72 MN / m 2 (77.2 kgf / cm 2), density 573 g / l, specific volume 1.745 10 -3 l / g. solubility of chlorine in water at a partial pressure of 14.8 (0 °C), 5.8 (30 °C), 2.8 (0.1 MN / m 2, or 1 kgf / cm 2 in water (g / l 70 ° C); 300 g / l NaCl 1. In a solution of 42 (30 ° C), 0.64 (70 ° C). Below 9.6 ° C, chlorine hydrates of variable composition Cl 2 NH 2 O (where N \u003d 6-8) are formed in aqueous solutions; These are yellow crystals of a cubic system, decomposing with increasing temperature in chlorine and water. Chlorine is readily soluble in TiCl 4, SiCl 4, SnCl 4 and some organic solvents (especially hexane C 6 H 14 and carbon tetrachloride CCl 4). The chlorine molecule is diatomic (Cl 2). The degree of thermal dissociation Cl 2 + 243 kJ \u003d 2Cl at 1000 K is 2.07 10 -4%, at 2500 K 0.909%. Easily soluble in SnCl 4 and some organic solvents (especially hexane C 6 H 14 and carbon tetrachloride CCl 4). The chlorine molecule is diatomic (Cl 2). The degree of thermal dissociation Cl 2 + 243 kJ \u003d 2Cl at 1000 K is 2.07 10 -4%, at 2500 K 0.909%. Easily soluble in SnCl 4 and some organic solvents (especially hexane C 6 H 14 and carbon tetrachloride CCl 4). The chlorine molecule is diatomic (Cl 2). The degree of thermal dissociation Cl 2 + 243 kJ \u003d 2Cl at 1000 K is 2.07 10 -4%, at 2500 K 0.909%. ( Cl2 Molar Mass)
Chlorine chemical properties. The outer electronic configuration of the atom is Cl 3s 2 3p 5. According to this, chlorine in compounds exhibits oxidation states of -1, +1, +3, +4, +5, +6 and +7. The atom’s covalent radius is 0.99 , the ionic radius of Cl is 1.82 , the electron affinity of the chlorine atom is 3.65 eV, and the ionization energy is 12.97 eV. ( Cl2 Molar Mass)
Chemically, chlorine is very active, it associates directly with almost all metals (only in the presence of moisture or when heated) and with non-metals (except carbon, nitrogen, oxygen, inert gases), the corresponding chlorides. reacts with many compounds, replacing hydrogen in saturated hydrocarbons and attaching to unsaturated compounds. Chlorine displaces bromine and iodine from its compounds with hydrogen and metals; It is displaced by fluorine from chlorine compounds with these elements. Alkali metals, in the presence of traces of moisture, interact with chlorine by ignition, most metals react only with dry chlorine when heated. Steel, as well as some metals, are resistant to dry chlorine environments at low temperatures, Therefore they are used for manufacturing equipment and dry chlorine storage facilities. Phosphorus ignites in an atmosphere of chlorine, which forms Cl 3, and upon further chlorination – l 5; Chlorinated sulfur when heated gives S 2 Cl 2, SCl 2 and other S n Cl m. Arsenic, antimony, bismuth, strontium, tellurium interact strongly with chlorine. The mixture of chlorine with hydrogen burns with a colorless or yellowish-green flame with the formation of hydrogen chloride (this is a chain reaction). Tellurium interacts strongly with chlorine. The mixture of chlorine with hydrogen burns with a colorless or yellowish-green flame with the formation of hydrogen chloride (this is a chain reaction). Tellurium interacts strongly with chlorine. The mixture of chlorine with hydrogen burns with a colorless or yellowish-green flame with the formation of hydrogen chloride (this is a chain reaction).
The maximum temperature of a hydrogen-chlorine flame is 2200 °C. The chlorine-hydrogen mixture contains from 5.8 to 88.5% H 2.
Chlorine forms oxides with oxygen: Cl 2 O, ClO 2, Cl 2 O 6, Cl 2 O 7, Cl 2 O 8, as well as hypochlorites (salts of hypochlorous acid), chlorites, chlorates and perchates. All oxygen-containing chlorine compounds form explosive mixtures with readily oxidizable substances. Oxides of chlorine are unstable and can explode spontaneously, hypochlorites decompose slowly during storage, chlorine and perchlorates can explode under the influence of initiators. ( Cl2 Molar Mass)
Chlorine in water is hydrolyzed, forming hypochlorous and hydrochloric acid: Cl 2 + H 2 O \u003d HClO + HCl. When chlorinated aqueous solutions of alkalis in the cold, hypochlorite and chloride are formed: 2NaOH + Cl 2 \u003d NaClO + NaCl + H 2 O, and when heated, chlorate. Chlorinated dry calcium hydroxide produces bleach. ( Cl2 Molar Mass)
When ammonia interacts with chlorine, nitrogen trichloride is formed. In the chlorination of organic compounds, chlorine either replaces hydrogen, or binds on multiple bonds, forming various chlorinated organic compounds. ( Cl2 Molar Mass)
Chlorine forms interhalogen compounds with other halogens. The fluorides ClF, ClF 3, ClF 3 are very reactive; For example, glass wool ignites spontaneously in a ClF 3 environment. Known compounds of chlorine with oxygen and fluorine – chlorine oxyfluorides: ClO 3F, ClO 2F 3, Klof, Klof 3 and fluorine perchlorate FClO 4.
chlorine production.Chlorine began to be produced commercially in 1785 by the interaction of hydrochloric acid with manganese(II) oxide or pyrolusite. In 1867, the English chemist G Deacon developed a method for producing chlorine by oxidizing HCl with atmospheric oxygen as a catalyst. From the late 19th – early 20th centuries, chlorine is produced by electrolysis of aqueous solutions of alkali metal chlorides. These methods produce 90-95% of the chlorine in the world. Small amounts of chlorine are produced by electrolysis of molten chloride to produce magnesium, calcium, sodium and lithium. There are two main methods of electrolysis of aqueous NaCl solutions: 1) in an electrolyzer with a solid cathode and a porous filtering diaphragm; 2) in an electrolyzer with a mercury cathode. Both methods produce chlorine gas at the graphite or titanium-ruthenium oxide anode. According to the first method, hydrogen is released at the cathode and a solution of NaOH and NaCl is formed, from which commercial caustic soda is separated by subsequent processing. According to the second method, sodium amalgam is formed at the cathode, when it is decomposed with purified water in a separate apparatus, a NaOH solution, hydrogen and pure mercury are obtained, which again goes into production. Both methods give 1.125 tonnes of NaOH per tonne of chlorine. When it is decomposed with pure water in a separate apparatus, a NaOH solution, hydrogen and pure mercury are obtained, which again goes into production. Both methods give 1.125 tonnes of NaOH per tonne of chlorine. When it is decomposed with pure water in a separate apparatus, a NaOH solution, hydrogen and pure mercury are obtained, which again goes into production. Both methods give 1.125 tonnes of NaOH per tonne of chlorine.
Diaphragm electrolysis for the organization of chlorine production requires less capital investment, gives cheaper NaOH. The mercury cathode method produces very pure NaOH, but the loss of mercury pollutes the environment.
chlorine applications. One of the important branches of the chemical industry is the chlorine industry. The major amount of chlorine is processed into chlorinated compounds at the site of its production. Chlorine is stored and transported in liquid form in cylinders, barrels, railway tanks or specially equipped vessels. For industrialized countries, the following estimated consumption of chlorine is typical: for the production of organic compounds containing chlorine – 60-75%; Chlorine-containing inorganic compounds, -10-20%; for bleaching cellulose and fabrics – 5-15%; For sanitary needs and water chlorination – 2-6% of total production. ( Cl2 Molar Mass)
Chlorine is also used for the chlorination of some ores to remove titanium, niobium, zirconium, and others. ( Cl2 Molar Mass)
Chlorine in the body.Chlorine is one of the biogenic elements, a constant component of plant and animal tissues. Chlorine content in plants (very high chlorine in halophytes) ranges from a thousand percent of one percent to a whole percent, in animals – in a tenth and a hundred percent. The daily requirement (2-4 g) of an adult for chlorine is covered by food. Chlorine is usually given with food in large amounts in the form of sodium chloride and potassium chloride. Bread, meat and dairy products are especially rich in chlorine. In animals, chlorine is the main active substance in blood plasma, lymph, cerebrospinal fluid and some tissues. plays a role in water-salt metabolism, Contributes to the retention of water by tissues. The regulation of the acid-base balance in tissues is carried out, among other processes, by changing the distribution of chlorine between the blood and other tissues. Chlorine is involved in energy metabolism in plants, activating both oxidative phosphorylation and photophosphorylation. Chlorine has a positive effect on oxygen uptake by the roots. Chlorine is required for the manufacture of oxygen by isolated chloroplasts during photosynthesis. Chlorine is not part of most nutrient mediums for artificial cultivation of plants. It is possible that very low concentrations of chlorine are sufficient for plant growth. which activates both oxidative phosphorylation and photophosphorylation. Chlorine has a positive effect on oxygen uptake by the roots. Chlorine is required for the manufacture of oxygen by isolated chloroplasts during photosynthesis. Chlorine is not part of most nutrient mediums for artificial cultivation of plants. It is possible that very low concentrations of chlorine are sufficient for plant growth. which activates both oxidative phosphorylation and photophosphorylation. Chlorine has a positive effect on oxygen uptake by the roots. Chlorine is required for the manufacture of oxygen by isolated chloroplasts during photosynthesis. Chlorine is not part of most nutrient mediums for artificial cultivation of plants. It is possible that very low concentrations of chlorine are sufficient for plant growth.
Chlorine poisoning is possible in the chemical, pulp and paper, textile, pharmaceutical industries, and others. Chlorine irritates the mucous membranes of the eyes and respiratory tract. A secondary infection is usually involved in the primary inflammatory changes. Acute poisoning develops almost immediately. Moderate and low concentrations of chlorine cause tightness and pain in the chest, dry cough, rapid breathing, pain in the eyes, lacrimation, increased leukocyte count in the blood, body temperature, etc. Possible bronchopneumonia, toxic pulmonary edema, depression, convulsions . … In mild cases, recovery occurs within 3-7 days. Inflammation of the upper respiratory tract, recurrent bronchitis, pneumosclerosis and others are observed as long-term consequences; Possible activation of pulmonary tuberculosis. With prolonged inhalation of small concentrations of chlorine, similar, but slowly developing forms of the disease are observed. Prevention of poisoning: Sealing of production facilities, equipment, effective ventilation, if necessary, the use of gas masks. The production of chlorine, bleach and other chlorine-containing compounds refers to industries with hazardous working conditions. ( Cl2 Molar Mass)
There is a small town in the west of Flanders. Nevertheless, its name is known throughout the world and will remain in the memory of mankind for a long time as a symbol of one of the greatest crimes against humanity. This city is Ypres. Kresi (At the Battle of Kresi in 1346, British soldiers used firearms for the first time in Europe.) – Ypres – Hiroshima – Milestones on the way to turning war into a giant destruction machine. ( Cl2 Molar Mass)
In early 1915, the main part of the so-called Ypres formed on the line of the Western Front. Allied Anglo-French forces occupied the north-east of Vayse in Comma, an area separated by German forces. The German command decided to launch a counterstrike and align the front line. On the morning of April 22, when the flat was drifting northeast, the Germans began unusual preparations for the offensive – they launched the first gas attack in the history of the war. On the Ypresky sector of the front, 6,000 chlorine cylinders were opened at once. Within five minutes, a huge, 180-ton, poisonous yellow-green cloud had formed, which slowly moved towards the enemy trenches.
Nobody expected this. French and British troops preparing an attack for artillery fire, the soldiers dug safely, but they were completely unarmed in the face of a devastating chlorine cloud. Deadly gas penetrated into all the crevices, into all the shelters. The consequences of the first chemical attack (and the first violation of the 1907 Hague Convention on the Non-use of Toxic Substances!) were staggering – chlorine killed about 15 thousand people, and about 5 thousand – up to death. And that’s all – to align the front line 6 km long! Two months later, the Germans launched a chlorine attack on the Eastern Front. And two years later, Ypres increased his notoriety. During a heavy fighting on July 12, 1917, a poisonous substance, later known as mustard gas, was first used in the area of this city. Mustard gas is a chlorine derivative, dichlorodiethyl sulfide. ( Cl2 Molar Mass)
We recounted these episodes from history, connected to a small town and a chemical element, to show how dangerous element 17 can be in the hands of terrorist lunatics. This is the darkest page in chlorine history. ( Cl2 Molar Mass)
But it would be completely wrong to see only one toxic substance in chlorine and the raw material for the production of other toxic substances …
Elemental chlorine has a relatively short history, dating back to 1774. The history of chlorine compounds is as old as in the world. Remembering that sodium chloride is table salt. And, apparently, the ability of salt to preserve meat and fish was observed even in prehistoric times.
The most ancient archaeological find – evidence of the use of salt by humans dates back to about 3 … 4 millennium BC. And the earliest description of rock salt mining is found in the writings of the Greek historian Herodotus (5th century BC). Herodotus describes the mining of rock salt in Libya. The famous temple of the god Ammon-Ra was located in the Sinah oasis in the center of the Libyan desert. That is why Libya was called “Ammonia”, and the first name of rock salt was “Sal Ammoniacum”. Later, about the XIII century began. AD, this name was assigned to ammonium chloride.
Pliny the Elder’s Natural History describes the method of separating gold from base metals by calcining salt and clay. And one of the first descriptions of the purification of sodium chloride is found in the works of the great Arab physician and alchemist Jabir ibn-Hayyan (European spelling – Geber).
It is very likely that chemists also encountered primary chlorine, since in the countries of the East already in the IX, and in Europe in the XIII century. Was known “Royal Vodka” – a mixture of hydrochloric and nitric acid. The book “Hortus Medicaine” by Dutchman van Helmont, published in 1668, states that when ammonium chloride and nitric acid are heated together, a type of gas is obtained. By description, this gas is similar to chlorine.
Chlorine was first described in detail by a Swedish chemist in his treatise on pyrolusite. Heating the pyrolusite mineral with hydrochloric acid, Scheel noted an odor characteristic of aqua regia, collected and examined the yellow-green gas that produced this odor, and studied its interactions with certain substances. Scheele was the first to discover the effect of chlorine on gold and cinnabar (in the latter case, mercury chloride is formed) and the bleaching properties of chlorine. ( Cl2 Molar Mass)
Scheele did not consider the newly discovered gas to be a simple substance and called it “diphlogisticated hydrochloric acid”. In modern terms, Schiele and other scientists after him believed that the new gas was hydrochloric acid oxide. ( Cl2 Molar Mass)
After some time, Berthollet and Lavoisier considered this gas to be an oxide of some new element “muria”. For three and a half decades, chemists have tried unsuccessfully to isolate the unknown murine.
At first, Dewey was also a supporter of “Muria Oxide”. In 1807 he decomposed table salt with an electric current into the alkali metal sodium and a yellow-green gas. However, three years later, after several fruitless attempts to obtain muria, Davy came to the conclusion that the gas discovered by Scheele was a simple substance, an element, and was referred to as chlorine gas or chlorine (Greek ,ζζ – yellow-). green) named. And three years later, Gay-Lussac gave the new element a shorter name – chlorine. True, in 1811 the German chemist Schweiger proposed another name for chlorine – “halogen” (literally its only form), but this name was taken not at first, but later for a whole group of elements. Became common, including chlorine.
Chlorine “Personal Card”
At least a dozen answers can be given to the question of what is chlorine. First of all, it is a halogen; secondly, one of the strongest oxidizing agents; Third, an extremely toxic gas; Fourth, the most important products of the main chemical industry; Fifth, raw materials for the production of plastics and pesticides, rubber and artificial fibres, dyes and medicines; Sixth, the substance with which titanium and silicone, glycerin and fluoroplastic are obtained; Seventh, a product for purifying drinking water and bleaching clothing…
This list can be continued.
Under normal conditions, elemental chlorine is a heavy yellow-green gas with a pungent characteristic odor. The atomic weight of chlorine is 35.453, and the molecular weight is 70.906, because the chlorine molecule is diatomic. Under normal conditions one liter of gaseous chlorine (temperature 0 °C and pressure 760 mm Hg) weighs 3.214 g. When cooled to a temperature of -34.05 ° C, chlorine condenses into a yellow liquid (density 1.56 g / cm 3), and at a temperature of – 101.6 ° C it hardens. At elevated pressures, chlorine can turn into a liquid at high temperatures up to + 144 ° C. Chlorine is readily soluble in dichloroethane and some other chlorine-containing organic solvents.
Element number 17 is very active – it binds directly to almost all the elements in the periodic table. Therefore, in nature, it is found only in the form of compounds. The most common minerals that contain chlorine are light NaCl, sylvinite KCl NaCl, biscophyte MgCl 2 6H 2 O, carnallite KCl MgCl 2 6H 2 O, kainite KCl MOCSO 4 3H 2 O. These are mainly “liquors” (or “qualifying”) that the chlorine content in the earth’s crust is 0.20% by weight. For non-ferrous metallurgy, some relatively rare chlorine-containing minerals are very important, for example, horn. Silver’s AgCl.
In terms of electrical conductivity, liquid chlorine is one of the strongest insulators: it is about a billion times worse than distilled water, and 10 to 22 times worse than silver.
The speed of sound in chlorine is about one and a half times less than in air.
And finally – about chlorine isotopes.
Nine isotopes of this element are now known, but only two are found in nature – chlorine-35 and chlorine-37. The first is almost three times more than the second.
The remaining seven isotopes are produced artificially. The shortest living among them – 32 Cl – has a half-life of 0.306 seconds, and the longest – 36 Cl – 310 thousand years.
How is chlorine obtained?
One thing you pay attention to when you get to a chlorine plant is several power lines. Chlorine production consumes a lot of electricity – it is needed to decompose natural chlorine compounds.
Naturally, the main raw material for chlorine is rock salt. If the chlorine plant is located near the river, then the salt is delivered not by rail, but by barge – it is more economical. Salt is a cheap product, but it is consumed a lot: to get one ton of chlorine, you need about 1.7 … 1.8 tons of salt.
The salt goes to the warehouses. Three – six months’ reserves of raw materials are stored here – chlorine production is usually on a large scale.
The salt is crushed and dissolved in hot water. This brine is sent through a pipeline to the cleaning workshop, where in huge tanks the height of a three-story building it is cleaned of impurities of calcium and magnesium salts and clarified (allowed to settle). A pure concentrated solution of sodium chloride is pumped to the main chlorine production shop – the chlorine production shop.
In an aqueous solution, sodium chloride molecules are converted into Na + and Cl – ions. Cl ion – differs from the chlorine atom only in that it has an extra electron. This means that in order to obtain primary chlorine, it is necessary to tear off this extra electron. This occurs at a positively charged electrode (anode) in the electrolyzer. It is as if electrons are “sucked up”: 2Cl – → Cl 2 + 2 … Anodes are made of graphite, because any metal (except platinum and its analogues), can take excess electrons from chlorine ions. Takes off, quickly corrodes and breaks.
There are two types of technical designs for chlorine production: diaphragm and mercury. In the first case, a perforated iron sheet serves as the cathode, and the cathode and anode spaces of the electrolyzer are separated by an asbestos diaphragm. At the iron cathode, a discharge of hydrogen ions occurs and an aqueous solution of sodium hydroxide is formed. If mercury is used as a cathode, sodium ions are discharged onto it and sodium amalgam is formed, which then dissociates with water. Hydrogen and caustic soda are obtained. In this case, a diaphragm seal is not needed, and the alkali is more concentrated than in diaphragm cells.
So, the production of chlorine is the production of caustic soda and hydrogen at the same time.
Hydrogen is removed through metal pipes and chlorine through glass or ceramic pipes. Freshly prepared chlorine is saturated with water vapor and therefore is particularly aggressive. Next, it is first cooled with cold water in tall towers, lined with ceramic tiles from the inside and filled with ceramic nozzles (so-called Raschig rings), and then dried with concentrated sulfuric acid. . It is the only chlorine and one of the few liquids that reacts with chlorine.
Dry chlorine is no longer aggressive, it does not destroy, for example, steel tools.
Chlorine is usually transported in liquid state in railway tanks or cylinders under pressure up to 10 tons.
In Russia, chlorine production was first organized in 1880 at the Bondiazhsky plant. Chlorine was obtained in principle in the same way as Scheele obtained it in due course – by the interaction of hydrochloric acid with pyrolite. All of the chlorine produced was used to obtain the bleach. In 1900, for the first time in Russia, a chlorine electrolytic production shop was put into operation at the Donsoda plant. The capacity of this shop was only 6 thousand tonnes per annum. In 1917, all chlorine plants in Russia produced 12 thousand tons of chlorine. And in 1965, the USSR produced about 1 million tons of chlorine …
one of many
All kinds of practical uses of chlorine can be expressed in one phrase without much stress: chlorine is essential for the production of chlorine products, ie. “Bound” chlorine-containing substances. But speaking of these very chlorine products, one phrase will not stop. They differ greatly – both in properties and in purpose.
The limited amount of our article does not allow us to tell about all chlorine compounds, but without a story about at least some substances that require chlorine, our “picture” of element number 17 is incomplete and will be unrelated.
For example, organochlorine insecticides – substances that kill harmful insects, but are safe for plants. A significant portion of the chlorine produced is consumed to obtain plant protection products.
One of the most important insecticides is hexachlorocyclohexane (often called hexachloran). This substance was first synthesized by Faraday back in 1825, but found practical application more than 100 years later – in the 30s of our century.
Now hexachlorene is obtained by chlorinating benzene. Like hydrogen, benzene reacts very slowly with chlorine in the dark (and in the absence of catalysts), but in bright light, the chlorination reaction of benzene (С 6 6 + 3Сl 2 → 6 6 т 6) Income is quick instead of 6.
Hexachloran, like many other insecticides, is used as a dust with fillers (talc, kaolin), or in the form of suspensions and emulsions, or, finally, as aerosols. Hexachloran is particularly effective in seed dressing and pest control of vegetable and fruit crops. The consumption of hexachlorane is only 1 … 3 kg per hectare, the economic effect of its use exceeds the cost by 10 … 15 times. Unfortunately, hexachloran is not harmful to humans …
If you asked any student to list the plastics he knew, he would be one of the first to name polyvinyl chloride (otherwise vinyl plastic). From a chemist’s point of view, PVC (as polyvinyl chloride is often denoted in the literature) is a polymer in a molecule in which hydrogen and chlorine atoms are strung on a chain of carbon atoms:
There may be several thousand links in this chain.
And from a consumer standpoint, PVC is insulation for wires and raincoats, linoleum and phonograph records, protective varnishes and packaging materials, chemical equipment and foams, toys and device parts.
Polyvinyl chloride is formed during the polymerization of vinyl chloride, most often obtained by treating acetylene with hydrogen chloride: HC + CH + HCl → CH 2 \u003d CHCl. There is another way to obtain vinyl chloride – thermal cracking of dichloroethane.
CH 2 Cl – CH 2 Cl → CH 2 \u003d CHCl + HCl. Of interest is the combination of these two methods, when HCl is used, which is released during the breakdown of dichloroethane, in the production of vinyl chloride by the acetylene method.
Vinyl chloride is a colorless gas with a pleasant, somewhat ethereal odor that polymerizes readily. To obtain a polymer, liquid vinyl chloride is injected under pressure into hot water, where it is crushed into tiny droplets. To prevent them from merging, a little gelatin or polyvinyl alcohol is added to the water, and in order to start the polymerization reaction to develop, the polymerization initiator, benzoyl peroxide, is also introduced there. After a few hours, the droplets solidify and suspending the polymer in water forms. The polymer powder is separated on a filter or centrifuge.
Polymerization usually occurs at a temperature of 40 to 60 °C, and the lower the polymerization temperature, the longer the polymer molecules can be formed…
We talked about only two substances for which you need element number 17. Only two out of many hundreds. There are many such examples. And they all say that chlorine is not only a toxic and dangerous gas, but a very important, very useful element.
When chlorine is obtained by electrolysis of a solution of sodium chloride, hydrogen and sodium hydroxide are simultaneously obtained: 2NACl + 2H 2 O \u003d H 2 + Cl 2 + 2NaOH. Of course, hydrogen is a very important chemical product, but there are cheaper and more convenient ways of producing this substance, for example, the conversion of natural gas … But caustic soda is almost exclusively obtained by electrolysis of sodium chloride solutions. is – other methods are less than 10%. Since the production of chlorine and NaOH is completely interconnected (as follows from the reaction equation, the production of one gram-molecule – 71 g of chlorine – is accompanied by the production of two gram-molecules of 80 g of electrolytic alkali) Knowing the productivity of the shop (or plant, or state). , You can easily calculate how much chlorine it produces. Each tonne of NaOH is “with” 890 kg of chlorine.
What a lubricant!
Concentrated sulfuric acid is practically the only liquid that does not interact with chlorine. Therefore, for the compression and pumping of chlorine in factories, pumps are used in which sulfuric acid plays the role of a working fluid and at the same time a lubricant.
Pseudonym of Friedrich Wohler
Investigation of the interaction of organic substances with chlorine, 19th century French chemist. Jean Dumas made an amazing discovery: chlorine is able to replace hydrogen in the molecules of organic compounds. For example, in the chlorination of acetic acid, the first hydrogen of the methyl group is replaced by chlorine, then another, a third… The competition was few. The range of reactions discovered by Dumas entirely by the electrochemical hypothesis and the theory of Berzelius’s principles that dominated at the time (according to the French chemist Laurent, the discovery of chloroacetic acid was like a meteor) that destroyed the whole old school Was. Berzelius, his students and followers vigorously disputed the correctness of Dumas’ work. German magazine”
chlorine and water
Chlorine dissolves exclusively in water. At 20 °C, 2.3 volumes of chlorine are dissolved in a volume of water. Aqueous solution of chlorine (chlorine water) – yellow. But over time, especially when stored in light, they gradually fade. This is explained by the fact that dissolved chlorine partially interacts with water, hydrochloric and hypochlorous acids are formed: Cl 2 + H 2 O → HCl + HOCl. The latter is unstable and slowly decomposes into HCl and oxygen. Therefore, the chlorine solution in water slowly turns into hydrochloric acid solution.
But at low temperatures, chlorine and water form a crystalline hydrate of an unusual structure – Cl 2 5 3/4 H 2 O. These greenish-yellow crystals (stable only at temperatures below 10 ° C) form ice water. can be obtained by passing chlorine from The unusual formula is explained by the structure of the crystalline hydrate, and is mainly determined by the composition of the ice. In the ice crystal lattice, H 2 O molecules can be arranged in such a way that regularly visible voids appear between them. The unit cubic cell contains 46 water molecules, with eight microscopic voids between them. Chlorine molecules settle in these voids. The exact formula for chlorine crystalline hydrate should therefore be written as follows: 8 h 2 46 2 g h.
The presence of about 0.0001% chlorine in the air is irritating to the mucous membranes. Persistent exposure to such an environment can lead to bronchial disease, dramatic hunger, and a greenish tint to the skin. If the chlorine content in the air is 0.1 ° / o, then acute poisoning can occur, the first sign of which is a severe coughing attack. In case of chlorine poisoning, complete rest is necessary; It is useful to inhale oxygen, or a pair of alcohol with ammonia (smelling ammonia), or ether. According to existing sanitary standards, the chlorine content in the air of industrial premises should not exceed 0.001 mg / l, i.e. 0.00003%.
not just poison
Everybody knows that wolves are greedy.” That chlorine is also toxic. However, in small doses, toxic chlorine can sometimes serve as an antidote. So, victims of hydrogen sulfide are given volatile bleach to smell. By interacting, the two poisons neutralize each other.
To determine the chlorine content, an air sample with an acidic solution of potassium iodide is passed through the absorber. (Chlorine displaces iodine, the amount of the latter is easily determined by titration with a solution of Na 2 S 2 O 3). To determine trace amounts of chlorine in air, a colorimetric method is often used, based on a sharp change in color of some compounds (benzidine, orthotoluidine, methyl orange) during their oxidation with chlorine. For example, a colorless acidified solution of benzene turns yellow, and neutral – blue. The intensity of the color is proportional to the amount of chlorine.
Chlorine – chemical element of group VII of the 3rd period of the periodic table of chemical elements D.I. Mendeleev. non metallic.
Refers to the elements of – p -family. Halogen. The serial number is 17. The structure of the outer electronic level is 3s 2 3 p 5. The relative atomic mass is 35.5 amu. The chlorine molecule is diatomic – Cl 2.
Chlorine Chemical Properties
Chlorine reacts with simple metals:
Cl 2 + 2Sb \u003d 2SbCl 3 (t);
Cl 2 + 2Fe \u003d 2FeCl 3;
Cl 2 + 2Na \u003d 2NaCl।
Chlorine interacts with simple substances, non-metals. Therefore, when interacting with phosphorus and sulfur, the corresponding chlorides are formed with fluorine – with fluorides, hydrogen – with hydrogen chloride, oxygen – with oxides, etc.
5Cl 2 + 2P \u003d 2HCl 5;
Cl 2 + 2S \u003d SCl 2;
Cl 2 + H 2 \u003d 2HCl;
Cl 2 + F 2 \u003d 2ClF।
Chlorine is able to displace bromine and iodine from its compounds with hydrogen and metals:
Cl 2 + 2HBr \u003d Br 2 + 2HCl;
Cl 2 + 2NaI \u003d I 2 + 2NaCl।
Chlorine is able to dissolve in water and alkalis, while denitrification reactions of chlorine occur, and the composition of the reaction products depends on the conditions for its implementation:
Cl 2 + H 2 O Cl HCl + HClO;
Cl 2 + 2NOH \ u003d NaCl + NaClO + H 2 O;
3 Cl 2 + 6NOH \ u003d 5NaCl + NaClO 3 + 3H 2 O.
Chlorine interacts with a non-salt forming oxide – CO to form a substance with a trivial name – phosgene with ammonium to form ammonium trichloride:
Cl 2 + CO \u003d COCl 2;
3 Cl 2 + 4 NH 3 \u003d NCl 3 + 3 NH 4 Cl.
In reactions, chlorine exhibits oxidizing properties:
Cl 2 + H 2 S \u003d 2HCl + S।
Chlorine interacts with organic substances of the class of alkanes, alkanes and arenes:
CH 3 -CH 3 + Cl 2 \u003d CH 3 -CH 2 -Cl + HCl (position – UV radiation);
CH 2 \u003d CH 2 + Cl 2 \u003d CH 2 (Cl) -2 HCl;
C 6 H 6 + Cl 2 \u003d C 6 H 5 -Cl + HCl (kat \u003d FeCl 3, AlCl 3);
C 6 H 6 + 6Cl 2 \u003d C 6 H 6 Cl 6 + 6HCl (position – UV radiation).
physical properties of chlorine
Chlorine is a yellow-green gas. It is thermally stable. When cold water is saturated with chlorine, a solid clarification is formed. It dissolves well in water, undergoes considerable dissolution (“chlorine water”). It dissolves in carbon tetrachloride, liquid SiCl 4 and TiCl 4. Poorly soluble in saturated sodium chloride solution. Does not react with oxygen. Strong oxidizing agent. The boiling point is -34.1C, the melting point is -101.03C.
Previously, chlorine was obtained by the Scheele method (reaction of manganese (VI) oxide with hydrochloric acid) or the Deacon method (reaction of the interaction of hydrogen chloride with oxygen):
MnO 2 + 4HCl \ u003d MnCl 2 + Cl 2 + 2H 2 हे;
4HCl + O 2 \u003d 2H 2 O + 2 Cl 2।
Nowadays, the following reactions are used to obtain chlorine:
NaOCl + 2HCl \ u003d NaCl + Cl 2 + H 2 O;
2KMnO 4 + 16HCl \u003d 2KCl + 2MnCl 2 + 5 Cl 2 + 8H 2 O;
2NaCl + 2H 2 O \u003d 2NaOH + Cl 2 + H 2 (position – electrolysis).
Chlorine finds widespread use in various fields of industry, as it is used for polymeric substances (polyvinyl chloride), bleach, organochlorine insecticides (hexachlorene), chemical warfare agents (Phosgene), for water disinfection, in the food industry, metallurgy, etc. is done in. ( Cl2 Molar Mass)