Chlorine designation in the table. See what “chlorine” is in other dictionaries. Effect of temperature on the state of aggregation of Cl
Considered physical properties chlorine: density of chlorine, its thermal conductivity, specific heat capacity and dynamic viscosity at different temperatures. The physical properties of Cl 2 are presented in the form of tables for the liquid, solid and gaseous states of this halogen.
Basic physical properties of chlorine
Chlorine is included in group VII of the third period of the periodic table of elements at number 17. It belongs to the subgroup of halogens, has relative atomic and molecular masses of 35.453 and 70.906, respectively. At temperatures above -30°C, chlorine is a greenish-yellow gas with a characteristic strong, irritating odor. It liquefies easily under normal pressure (1.013·10 5 Pa) when cooled to -34°C, and forms a clear amber liquid that solidifies at -101°C.
Due to its high chemical activity, free chlorine does not occur in nature, but exists only in the form of compounds. It is found mainly in the mineral halite (), and is also part of such minerals as sylvite (KCl), carnallite (KCl MgCl 2 6H 2 O) and sylvinite (KCl NaCl). Chlorine content in earth's crust approaches 0.02% of the total number of atoms of the earth's crust, where it is found in the form of two isotopes 35 Cl and 37 Cl in a percentage ratio of 75.77% 35 Cl and 24.23% 37 Cl.
| Property | Meaning |
|---|---|
| Melting point, °C | -100,5 |
| Boiling point, °C | -30,04 |
| Critical temperature, °C | 144 |
| Critical pressure, Pa | 77.1 10 5 |
| Critical density, kg/m 3 | 573 |
| Gas density (at 0°C and 1.013 10 5 Pa), kg/m 3 | 3,214 |
| Saturated steam density (at 0°C and 3.664 10 5 Pa), kg/m 3 | 12,08 |
| Density liquid chlorine(at 0°C and 3.664 10 5 Pa), kg/m 3 | 1468 |
| Density of liquid chlorine (at 15.6°C and 6.08 10 5 Pa), kg/m 3 | 1422 |
| Density of solid chlorine (at -102°C), kg/m 3 | 1900 |
| Relative density of gas in air (at 0°C and 1.013 10 5 Pa) | 2,482 |
| Relative density of saturated steam in air (at 0°C and 3.664 10 5 Pa) | 9,337 |
| Relative density of liquid chlorine at 0°C (relative to water at 4°C) | 1,468 |
| Specific volume of gas (at 0°C and 1.013 10 5 Pa), m 3 /kg | 0,3116 |
| Specific volume of saturated steam (at 0°C and 3.664 10 5 Pa), m 3 /kg | 0,0828 |
| Specific volume of liquid chlorine (at 0°C and 3.664 10 5 Pa), m 3 /kg | 0,00068 |
| Chlorine vapor pressure at 0°C, Pa | 3.664 10 5 |
| Dynamic viscosity of gas at 20°C, 10 -3 Pa s | 0,013 |
| Dynamic viscosity of liquid chlorine at 20°C, 10 -3 Pa s | 0,345 |
| Heat of fusion of solid chlorine (at melting point), kJ/kg | 90,3 |
| Heat of vaporization (at boiling point), kJ/kg | 288 |
| Heat of sublimation (at melting point), kJ/mol | 29,16 |
| Molar heat capacity C p of gas (at -73…5727°C), J/(mol K) | 31,7…40,6 |
| Molar heat capacity C p of liquid chlorine (at -101…-34°C), J/(mol K) | 67,1…65,7 |
| Gas thermal conductivity coefficient at 0°C, W/(m K) | 0,008 |
| Thermal conductivity coefficient of liquid chlorine at 30°C, W/(m K) | 0,62 |
| Gas enthalpy, kJ/kg | 1,377 |
| Enthalpy of saturated steam, kJ/kg | 1,306 |
| Enthalpy of liquid chlorine, kJ/kg | 0,879 |
| Refractive index at 14°C | 1,367 |
| Specific electrical conductivity at -70°С, S/m | 10 -18 |
| Electron affinity, kJ/mol | 357 |
| Ionization energy, kJ/mol | 1260 |
Chlorine Density
Under normal conditions, chlorine is a heavy gas with a density approximately 2.5 times higher. Density of gaseous and liquid chlorine under normal conditions (at 0°C) is equal to 3.214 and 1468 kg/m3, respectively. When liquid or gaseous chlorine is heated, its density decreases due to an increase in volume due to thermal expansion.
Density of chlorine gas
The table shows the density of chlorine in the gaseous state at various temperatures (ranging from -30 to 140°C) and normal atmospheric pressure (1.013·10 5 Pa). The density of chlorine changes with temperature - it decreases when heated. For example, at 20°C the density of chlorine is 2.985 kg/m3, and when the temperature of this gas increases to 100°C, the density value decreases to a value of 2.328 kg/m 3.
| t, °С | ρ, kg/m 3 | t, °С | ρ, kg/m 3 |
|---|---|---|---|
| -30 | 3,722 | 60 | 2,616 |
| -20 | 3,502 | 70 | 2,538 |
| -10 | 3,347 | 80 | 2,464 |
| 0 | 3,214 | 90 | 2,394 |
| 10 | 3,095 | 100 | 2,328 |
| 20 | 2,985 | 110 | 2,266 |
| 30 | 2,884 | 120 | 2,207 |
| 40 | 2,789 | 130 | 2,15 |
| 50 | 2,7 | 140 | 2,097 |
As pressure increases, the density of chlorine increases. The tables below show the density of chlorine gas in the temperature range from -40 to 140°C and pressure from 26.6·10 5 to 213·10 5 Pa. With increasing pressure, the density of chlorine in the gaseous state increases proportionally. For example, an increase in chlorine pressure from 53.2·10 5 to 106.4·10 5 Pa at a temperature of 10°C leads to a twofold increase in the density of this gas.
| ↓ t, °С | P, kPa → | 26,6 | 53,2 | 79,8 | 101,3 |
|---|---|---|---|---|
| -40 | 0,9819 | 1,996 | — | — |
| -30 | 0,9402 | 1,896 | 2,885 | 3,722 |
| -20 | 0,9024 | 1,815 | 2,743 | 3,502 |
| -10 | 0,8678 | 1,743 | 2,629 | 3,347 |
| 0 | 0,8358 | 1,678 | 2,528 | 3,214 |
| 10 | 0,8061 | 1,618 | 2,435 | 3,095 |
| 20 | 0,7783 | 1,563 | 2,35 | 2,985 |
| 30 | 0,7524 | 1,509 | 2,271 | 2,884 |
| 40 | 0,7282 | 1,46 | 2,197 | 2,789 |
| 50 | 0,7055 | 1,415 | 2,127 | 2,7 |
| 60 | 0,6842 | 1,371 | 2,062 | 2,616 |
| 70 | 0,6641 | 1,331 | 2 | 2,538 |
| 80 | 0,6451 | 1,292 | 1,942 | 2,464 |
| 90 | 0,6272 | 1,256 | 1,888 | 2,394 |
| 100 | 0,6103 | 1,222 | 1,836 | 2,328 |
| 110 | 0,5943 | 1,19 | 1,787 | 2,266 |
| 120 | 0,579 | 1,159 | 1,741 | 2,207 |
| 130 | 0,5646 | 1,13 | 1,697 | 2,15 |
| 140 | 0,5508 | 1,102 | 1,655 | 2,097 |
| ↓ t, °С | P, kPa → | 133 | 160 | 186 | 213 |
|---|---|---|---|---|
| -20 | 4,695 | 5,768 | — | — |
| -10 | 4,446 | 5,389 | 6,366 | 7,389 |
| 0 | 4,255 | 5,138 | 6,036 | 6,954 |
| 10 | 4,092 | 4,933 | 5,783 | 6,645 |
| 20 | 3,945 | 4,751 | 5,565 | 6,385 |
| 30 | 3,809 | 4,585 | 5,367 | 6,154 |
| 40 | 3,682 | 4,431 | 5,184 | 5,942 |
| 50 | 3,563 | 4,287 | 5,014 | 5,745 |
| 60 | 3,452 | 4,151 | 4,855 | 5,561 |
| 70 | 3,347 | 4,025 | 4,705 | 5,388 |
| 80 | 3,248 | 3,905 | 4,564 | 5,225 |
| 90 | 3,156 | 3,793 | 4,432 | 5,073 |
| 100 | 3,068 | 3,687 | 4,307 | 4,929 |
| 110 | 2,985 | 3,587 | 4,189 | 4,793 |
| 120 | 2,907 | 3,492 | 4,078 | 4,665 |
| 130 | 2,832 | 3,397 | 3,972 | 4,543 |
| 140 | 2,761 | 3,319 | 3,87 | 4,426 |
Density of liquid chlorine
Liquid chlorine can exist in a relatively narrow temperature range, the boundaries of which lie from minus 100.5 to plus 144 ° C (that is, from the melting point to the critical temperature). Above a temperature of 144°C, chlorine will not turn into a liquid state under any pressure. The density of liquid chlorine in this temperature range varies from 1717 to 573 kg/m3.
| t, °С | ρ, kg/m 3 | t, °С | ρ, kg/m 3 |
|---|---|---|---|
| -100 | 1717 | 30 | 1377 |
| -90 | 1694 | 40 | 1344 |
| -80 | 1673 | 50 | 1310 |
| -70 | 1646 | 60 | 1275 |
| -60 | 1622 | 70 | 1240 |
| -50 | 1598 | 80 | 1199 |
| -40 | 1574 | 90 | 1156 |
| -30 | 1550 | 100 | 1109 |
| -20 | 1524 | 110 | 1059 |
| -10 | 1496 | 120 | 998 |
| 0 | 1468 | 130 | 920 |
| 10 | 1438 | 140 | 750 |
| 20 | 1408 | 144 | 573 |
Specific heat capacity of chlorine
The specific heat capacity of chlorine gas C p in kJ/(kg K) in the temperature range from 0 to 1200°C and normal atmospheric pressure can be calculated using the formula:
where T is the absolute temperature of chlorine in degrees Kelvin.
It should be noted that under normal conditions the specific heat capacity of chlorine is 471 J/(kg K) and increases when heated. The increase in heat capacity at temperatures above 500°C becomes insignificant, and at high temperatures The specific heat capacity of chlorine remains virtually unchanged.
The table shows the results of calculating the specific heat of chlorine using the above formula (the calculation error is about 1%).
| t, °С | C p , J/(kg K) | t, °С | C p , J/(kg K) |
|---|---|---|---|
| 0 | 471 | 250 | 506 |
| 10 | 474 | 300 | 508 |
| 20 | 477 | 350 | 510 |
| 30 | 480 | 400 | 511 |
| 40 | 482 | 450 | 512 |
| 50 | 485 | 500 | 513 |
| 60 | 487 | 550 | 514 |
| 70 | 488 | 600 | 514 |
| 80 | 490 | 650 | 515 |
| 90 | 492 | 700 | 515 |
| 100 | 493 | 750 | 515 |
| 110 | 494 | 800 | 516 |
| 120 | 496 | 850 | 516 |
| 130 | 497 | 900 | 516 |
| 140 | 498 | 950 | 516 |
| 150 | 499 | 1000 | 517 |
| 200 | 503 | 1100 | 517 |
At temperatures close to absolute zero, chlorine is in a solid state and has a low specific heat capacity (19 J/(kg K)). As the temperature of solid Cl 2 increases, its heat capacity increases and reaches a value of 720 J/(kg K) at minus 143°C.
Liquid chlorine has a specific heat capacity of 918...949 J/(kg K) in the range from 0 to -90 degrees Celsius. The table shows that the specific heat capacity of liquid chlorine is higher than that of gaseous chlorine and decreases with increasing temperature.
Thermal conductivity of chlorine
The table shows the values of the thermal conductivity coefficients of chlorine gas at normal atmospheric pressure in the temperature range from -70 to 400°C.
The thermal conductivity coefficient of chlorine under normal conditions is 0.0079 W/(m deg), which is 3 times less than at the same temperature and pressure. Heating chlorine leads to an increase in its thermal conductivity. Thus, at a temperature of 100°C, the value of this physical property of chlorine increases to 0.0114 W/(m deg).
| t, °С | λ, W/(m deg) | t, °С | λ, W/(m deg) |
|---|---|---|---|
| -70 | 0,0054 | 50 | 0,0096 |
| -60 | 0,0058 | 60 | 0,01 |
| -50 | 0,0062 | 70 | 0,0104 |
| -40 | 0,0065 | 80 | 0,0107 |
| -30 | 0,0068 | 90 | 0,0111 |
| -20 | 0,0072 | 100 | 0,0114 |
| -10 | 0,0076 | 150 | 0,0133 |
| 0 | 0,0079 | 200 | 0,0149 |
| 10 | 0,0082 | 250 | 0,0165 |
| 20 | 0,0086 | 300 | 0,018 |
| 30 | 0,009 | 350 | 0,0195 |
| 40 | 0,0093 | 400 | 0,0207 |
Chlorine viscosity
The coefficient of dynamic viscosity of gaseous chlorine in the temperature range 20...500°C can be approximately calculated using the formula:
where η T is the coefficient of dynamic viscosity of chlorine at a given temperature T, K;
η T 0 - coefficient of dynamic viscosity of chlorine at temperature T 0 = 273 K (at normal conditions);
C is the Sutherland constant (for chlorine C = 351).
Under normal conditions, the dynamic viscosity of chlorine is 0.0123·10 -3 Pa·s. When heated, the physical property of chlorine, such as viscosity, takes on higher values.
Liquid chlorine has a viscosity an order of magnitude higher than gaseous chlorine. For example, at a temperature of 20°C, the dynamic viscosity of liquid chlorine has a value of 0.345·10 -3 Pa·s and decreases with increasing temperature.
Sources:
- Barkov S. A. Halogens and the manganese subgroup. Elements of group VII of the periodic table of D. I. Mendeleev. A manual for students. M.: Education, 1976 - 112 p.
- Tables physical quantities. Directory. Ed. acad. I. K. Kikoina. M.: Atomizdat, 1976 - 1008 p.
- Yakimenko L. M., Pasmanik M. I. Handbook on the production of chlorine, caustic soda and basic chlorine products. Ed. 2nd, per. and others. M.: Chemistry, 1976 - 440 p.
Chlorine
CHLORINE-A; m.[from Greek chlōros - pale green] Chemical element (Cl), an asphyxiating gas of greenish-yellow color with a pungent odor (used as a poisonous and disinfectant). Chlorine compounds. Chlorine poisoning.
◁ Chlorine (see).
chlorine(lat. Chlorum), a chemical element of group VII of the periodic table, belongs to the halogens. The name comes from the Greek chlōros - yellow-green. Free chlorine consists of diatomic molecules (Cl 2); yellow-green gas with a pungent odor; density 3.214 g/l; t pl -101°C; t kip -33.97°C; at ordinary temperatures it easily liquefies under a pressure of 0.6 MPa. Chemically very active (oxidizing agent). The main minerals are halite (rock salt), sylvite, bischofite; sea water contains chlorides of sodium, potassium, magnesium and other elements. They are used in the production of chlorine-containing organic compounds (60-75%), inorganic substances (10-20%), for bleaching cellulose and fabrics (5-15%), for sanitary needs and disinfection (chlorination) of water. Toxic.
CHLORINECHLORINE (lat. Chlorum), Cl (read “chlorine”), chemical element with atomic number 17, atomic mass 35.453. In its free form it is a yellow-green heavy gas with a sharp suffocating odor (hence the name: Greek chloros - yellow-green).
Natural chlorine is a mixture of two nuclides (cm. NUCLIDE) with mass numbers of 35 (in a mixture of 75.77% by mass) and 37 (24.23%). Outer electron layer 3 configuration s 2
p 5
. In compounds it exhibits mainly oxidation states –1, +1, +3, +5 and +7 (valences I, III, V and VII). Located in the third period in group VIIA of Mendeleev’s periodic table of elements, belongs to the halogens (cm. HALOGEN).
The radius of the neutral chlorine atom is 0.099 nm, the ionic radii are, respectively (the values of the coordination number are indicated in parentheses): Cl - 0.167 nm (6), Cl 5+ 0.026 nm (3) and Clr 7+ 0.022 nm (3) and 0.041 nm ( 6). The sequential ionization energies of the neutral chlorine atom are, respectively, 12.97, 23.80, 35.9, 53.5, 67.8, 96.7 and 114.3 eV. Electron affinity 3.614 eV. According to the Pauling scale, the electronegativity of chlorine is 3.16.
History of discovery
The most important chemical compound of chlorine is table salt ( chemical formula NaCl, chemical name sodium chloride) has been known to man since ancient times. There is evidence that the extraction of table salt was carried out as early as 3-4 thousand years BC in Libya. It is possible that, using table salt for various manipulations, alchemists also encountered chlorine gas. To dissolve the “king of metals” - gold - they used “regia vodka” - a mixture of hydrochloric and nitric acids, the interaction of which releases chlorine.
For the first time, chlorine gas was obtained and described in detail by the Swedish chemist K. Scheele (cm. SCHEELE Karl Wilhelm) in 1774. He heated hydrochloric acid with the mineral pyrolusite (cm. PYROLUSITE) MnO 2 and observed the release of a yellow-green gas with a pungent odor. Since the theory of phlogiston dominated in those days (cm. PHLOGISTON), Scheele considered the new gas as “dephlogistonized hydrochloric acid,” i.e., as an oxide (oxide) of hydrochloric acid. A. Lavoisier (cm. LAVOISIER Antoine Laurent) considered the gas as an oxide of the element “muria” (hydrochloric acid was called muric acid, from the Latin muria - brine). The same point of view was first shared by the English scientist G. Davy (cm. DAVY Humphrey), who spent a lot of time breaking down “murium oxide” into simple substances. He failed, and by 1811 Davy came to the conclusion that this gas is a simple substance, and a chemical element corresponds to it. Davy was the first to suggest calling it chlorine in accordance with the yellow-green color of the gas. The name “chlorine” was given to the element in 1812 by the French chemist J. L. Gay-Lussac (cm. GAY LUSSAC Joseph Louis); it is accepted in all countries except Great Britain and the USA, where the name introduced by Davy has been preserved. It was suggested that this element should be called “halogen” (i.e., salt-producing), but over time it became the general name for all elements of group VIIA.
Being in nature
The chlorine content in the earth's crust is 0.013% by weight; it is present in noticeable concentrations in the form of the Cl – ion in sea water (on average about 18.8 g/l). Chemically, chlorine is highly active and therefore does not occur in free form in nature. It is part of such minerals that form large deposits, such as table, or rock, salt (halite (cm. HALITE)) NaCl, carnallite (cm. CARNALLITE) KCl MgCl 2 6H 21 O, sylvine (cm. SYLVIN) KCl, sylvinite (Na, K)Cl, kainite (cm. KAINIT) KCl MgSO 4 3H 2 O, bischofite (cm. BISCHOFIT) MgCl 2 ·6H 2 O and many others. Chlorine can be found in most different breeds, in the soil.
Receipt
To produce chlorine gas, electrolysis of a strong aqueous solution of NaCl is used (sometimes KCl is used). Electrolysis is carried out using a cation exchange membrane separating the cathode and anode spaces. Moreover, due to the process
2NaCl + 2H 2 O = 2NaOH + H 2 + Cl 2
three valuable chemical products are obtained at once: chlorine at the anode, hydrogen at the cathode (cm. HYDROGEN), and alkali accumulates in the electrolyzer (1.13 tons of NaOH for every ton of chlorine produced). The production of chlorine by electrolysis requires large amounts of electricity: from 2.3 to 3.7 MW is consumed to produce 1 ton of chlorine.
To obtain chlorine in the laboratory, they use the reaction of concentrated hydrochloric acid with any strong oxidizing agent (potassium permanganate KMnO 4, potassium dichromate K 2 Cr 2 O 7, potassium chlorate KClO 3, bleach CaClOCl, manganese (IV) oxide MnO 2). It is most convenient to use potassium permanganate for these purposes: in this case, the reaction proceeds without heating:
2KMnO 4 + 16HCl = 2KСl + 2MnCl 2 + 5Cl 2 + 8H 2 O.
If necessary, chlorine in liquefied (under pressure) form is transported in railway tanks or in steel cylinders. Chlorine cylinders have a special marking, but even without it, a chlorine cylinder can be easily distinguished from cylinders with other non-toxic gases. The bottom of chlorine cylinders is shaped like a hemisphere, and a cylinder with liquid chlorine cannot be placed vertically without support.
Physical and Chemical properties
Under normal conditions, chlorine is a yellow-green gas, the gas density at 25°C is 3.214 g/dm 3 (about 2.5 times the density of air). The melting point of solid chlorine is –100.98°C, the boiling point is –33.97°C. The standard electrode potential Cl 2 /Cl - in an aqueous solution is +1.3583 V.
In the free state, it exists in the form of diatomic Cl 2 molecules. The internuclear distance in this molecule is 0.1987 nm. The electron affinity of the Cl 2 molecule is 2.45 eV, ionization potential is 11.48 eV. The energy of dissociation of Cl 2 molecules into atoms is relatively low and amounts to 239.23 kJ/mol.
Chlorine is slightly soluble in water. At a temperature of 0°C, the solubility is 1.44 wt.%, at 20°C - 0.711°C wt.%, at 60°C - 0.323 wt. %. A solution of chlorine in water is called chlorine water. In chlorine water an equilibrium is established:
Сl 2 + H 2 O H + = Сl - + HOСl.
In order to shift this equilibrium to the left, i.e., reduce the solubility of chlorine in water, either sodium chloride NaCl or some non-volatile strong acid (for example, sulfuric) should be added to the water.
Chlorine is highly soluble in many non-polar liquids. Liquid chlorine itself serves as a solvent for substances such as BCl 3, SiCl 4, TiCl 4.
Due to the low dissociation energy of Cl 2 molecules into atoms and the high electron affinity of the chlorine atom, chemically chlorine is highly active. It reacts directly with most metals (including, for example, gold) and many non-metals. So, without heating, chlorine reacts with alkaline (cm. ALKALI METALS) and alkaline earth metals (cm. ALKALINE EARTH METALS), with antimony:
2Sb + 3Cl 2 = 2SbCl 3
When heated, chlorine reacts with aluminum:
3Сl 2 + 2Аl = 2А1Сl 3
and iron:
2Fe + 3Cl 2 = 2FeCl 3.
Chlorine reacts with hydrogen H2 either when ignited (chlorine burns quietly in a hydrogen atmosphere), or when a mixture of chlorine and hydrogen is irradiated with ultraviolet light. In this case, hydrogen chloride gas HCl appears:
H 2 + Cl 2 = 2HCl.
A solution of hydrogen chloride in water is called hydrochloric acid (cm. HYDROCHLORIC ACID)(hydrochloric) acid. The maximum mass concentration of hydrochloric acid is about 38%. Salts of hydrochloric acid - chlorides (cm. CHLORIDE), for example, ammonium chloride NH 4 Cl, calcium chloride CaCl 2, barium chloride BaCl 2 and others. Many chlorides are highly soluble in water. Silver chloride AgCl is practically insoluble in water and in acidic aqueous solutions. A qualitative reaction to the presence of chloride ions in a solution is the formation of a white AgCl precipitate with Ag + ions, practically insoluble in a nitric acid medium:
CaCl 2 + 2AgNO 3 = Ca(NO 3) 2 + 2AgCl.
At room temperature chlorine reacts with sulfur (the so-called sulfur monochloride S 2 Cl 2 is formed) and fluorine (the compounds ClF and ClF 3 are formed). When heated, chlorine interacts with phosphorus (forming, depending on the reaction conditions, compounds PCl 3 or PCl 5), arsenic, boron and other non-metals. Chlorine does not react directly with oxygen, nitrogen, carbon (numerous chlorine compounds with these elements are obtained indirectly) and inert gases (in Lately scientists have found ways to activate such reactions and carry them out “directly”). With other halogens, chlorine forms interhalogen compounds, for example, very strong oxidizing agents - fluorides ClF, ClF 3, ClF 5. The oxidizing power of chlorine is higher than bromine, so chlorine displaces bromide ion from bromide solutions, for example:
Cl 2 + 2NaBr = Br 2 + 2NaCl
Chlorine undergoes substitution reactions with many organic compounds, for example, with methane CH4 and benzene C6H6:
CH 4 + Cl 2 = CH 3 Cl + HCl or C 6 H 6 + Cl 2 = C 6 H 5 Cl + HCl.
A chlorine molecule is capable of attaching via multiple bonds (double and triple) to organic compounds, for example, to ethylene C 2 H 4:
C 2 H 4 + Cl 2 = CH 2 Cl CH 2 Cl.
Chlorine interacts with aqueous solutions of alkalis. If the reaction occurs at room temperature, chloride (for example, potassium chloride KCl) and hypochlorite are formed (cm. HYPOCHLORITES)(for example, potassium hypochlorite KClO):
Cl 2 + 2KOH = KClO + KCl + H 2 O.
When chlorine interacts with a hot (temperature about 70-80°C) alkali solution, the corresponding chloride and chlorate are formed (cm. CHLORATES), For example:
3Cl 2 + 6KOH = 5KCl + KClO 3 + 3H 2 O.
When chlorine interacts with a wet slurry of calcium hydroxide Ca(OH) 2, bleach is formed (cm. BLEACHING POWDER)(“bleach”) CaClOCl.
The oxidation state of chlorine +1 corresponds to weak, unstable hypochlorous acid (cm. Hypochlorous acid) HClO. Its salts are hypochlorites, for example, NaClO - sodium hypochlorite. Hypochlorites are strong oxidizing agents and are widely used as bleaching and disinfecting agents. When hypochlorites, in particular bleach, interact with carbon dioxide CO 2 is formed among other products, volatile hypochlorous acid (cm. Hypochlorous acid), which can decompose to release chlorine oxide (I) Cl 2 O:
2HClO = Cl 2 O + H 2 O.
It is the smell of this gas, Cl 2 O, that is the characteristic smell of “bleach.”
The oxidation state of chlorine +3 corresponds to the low-stable acid of medium strength HClO 2. This acid is called chloric acid, its salts are called chlorites (cm. CHLORITES (salts)), for example, NaClO 2 - sodium chlorite.
The oxidation state of chlorine +4 corresponds to only one compound - chlorine dioxide ClO 2.
The oxidation state of chlorine +5 corresponds to strong, stable only in aqueous solutions at concentrations below 40%, perchloric acid (cm. Hypochlorous acid) HClO 3. Its salts are chlorates, for example, potassium chlorate KClO 3.
The oxidation state of chlorine +6 corresponds to only one compound - chlorine trioxide ClO 3 (exists in the form of a dimer Cl 2 O 6).
The oxidation state of chlorine +7 corresponds to a very strong and fairly stable perchloric acid (cm. PERCHLORIC ACID) HClO 4. Its salts are perchlorates (cm. PERCHLORATES), for example, ammonium perchlorate NH 4 ClO 4 or potassium perchlorate KClO 4. It should be noted that perchlorates of heavy alkali metals - potassium, and especially rubidium and cesium - are slightly soluble in water. The oxide corresponding to the oxidation state of chlorine is +7 - Cl 2 O 7.
Among compounds containing chlorine in positive oxidation states, hypochlorites have the strongest oxidizing properties. For perchlorates, oxidizing properties are uncharacteristic.
Application
Chlorine is one of the most important products of the chemical industry. Its global production amounts to tens of millions of tons per year. Chlorine is used to produce disinfectants and bleaches (sodium hypochlorite, bleach and others), hydrochloric acid, chlorides of many metals and non-metals, many plastics (polyvinyl chloride (cm. POLYVINYL CHLORIDE) and others), chlorine-containing solvents (dichloroethane CH 2 ClCH 2 Cl, carbon tetrachloride CCl 4, etc.), for opening ores, separating and purifying metals, etc. Chlorine is used to disinfect water (chlorination (cm. CHLORINATION)) and for many other purposes.
Biological role
Chlorine is one of the most important biogenic elements (cm. BIOGENIC ELEMENTS) and is part of all living organisms. Some plants, the so-called halophytes, are not only able to grow on highly saline soils, but also accumulate in large quantities chlorides. Microorganisms (halobacteria, etc.) and animals are known that live in conditions of high salinity. Chlorine is one of the main elements of water-salt metabolism in animals and humans, determining physical and chemical processes in the tissues of the body. It is involved in maintaining acid-base balance in tissues, osmoregulation (cm. OSMOREGULATION)(chlorine is the main osmotically active substance blood, lymph and other body fluids), being mainly outside the cells. In plants, chlorine takes part in oxidative reactions and photosynthesis.
Human muscle tissue contains 0.20-0.52% chlorine, bone tissue - 0.09%; in the blood - 2.89 g/l. The average person's body (body weight 70 kg) contains 95 g of chlorine. Every day a person receives 3-6 g of chlorine from food, which more than covers the need for this element.
Features of working with chlorine
Chlorine is a poisonous asphyxiating gas; if it enters the lungs, it causes burns of lung tissue and suffocation. It has an irritating effect on the respiratory tract at a concentration in the air of about 0.006 mg/l. Chlorine was one of the first chemical poisons (cm. POISONIC SUBSTANCES), used by Germany in the First world war. When working with chlorine, you should use protective clothing, a gas mask, and gloves. For a short time, you can protect the respiratory organs from chlorine entering them with a cloth bandage moistened with a solution of sodium sulfite Na 2 SO 3 or sodium thiosulfate Na 2 S 2 O 3. Maximum concentration of chlorine in the air of working premises is 1 mg/m 3, in the air settlements 0.03 mg/m3.
encyclopedic Dictionary. 2009 .
Synonyms:See what “chlorine” is in other dictionaries:
Chlorine, eh... Russian word stress
chlorine- chlorine, and... Russian spelling dictionary
chlorine- chlorine/... Morphemic-spelling dictionary
- (Greek chloros greenish yellow). Chemically simple, gaseous body, greenish yellow color, pungent, irritating odor, having the ability to discolor plant matter. Dictionary foreign words, included in the Russian language... Dictionary of foreign words of the Russian language
- (symbol C1), a widespread non-metallic element, one of the HALOGENS (elements of the seventh group of the periodic table), first discovered in 1774. It is part of table salt (NaCl). Chlorine is a greenish yellow... Scientific and technical encyclopedic dictionary
CHLORINE- CHLORINE, C12, chemical. element, atomic number 17, atomic weight 35.457. Being in group VII of period III, chlorine atoms have 7 outer electrons, due to which X behaves like a typical monovalent metalloid. X. divided into isotopes with atomic... ... Great Medical Encyclopedia
Chlorine- usually obtained by electrolysis of alkali metal chlorides, in particular sodium chloride. Chlorine is a greenish-yellow, asphyxiating, corrosive gas that is 2.5 times denser than air, slightly soluble in water, and easily liquefied. Usually transported... Official terminology
Chlorine- (Chlorum), Cl, chemical element of group VII of the periodic table, atomic number 17, atomic mass 35.453; refers to halogens; yellow-green gas, boiling point 33.97°C. Used in the production of polyvinyl chloride, chloroprene rubber,... ... Illustrated Encyclopedic Dictionary
CHLORINE, chlorine, pl. no, husband (from Greek chloros green) (chemical). Chemical element, asphyxiating gas, used. in technology, in sanitation as a disinfectant and in warfare as a poisonous substance. Ushakov's explanatory dictionary. D.N. Ushakov. 1935 1940 ... Ushakov's Explanatory Dictionary
Chlorine... The initial part of complex words, introducing the meaning of the following: chlorine, chloride (organochlorine, chloroacetone, chlorobenzene, chloromethane, etc.). Ephraim's explanatory dictionary. T. F. Efremova. 2000... Modern Dictionary Russian language Efremova
Books
- Russian theater or Complete collection of all Russian theatrical works. Part 24. Operas: Guardian Professor. - I. Knyazhnin. Misfortune from the carriage. - Dushinka's joy. - Sailor jokes. - . Chlor Tsarevich, , . The book is a reprint of 1786. Despite the fact that serious work has been done to restore the original quality of the publication, some pages may...
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 = Cl 2 + MnCl 2 + 2H 2 O
Scheele noted the odor of chlorine, similar to that of aqua regia, its ability to react with gold and cinnabar, and its bleaching properties. However, Scheele, in accordance with the phlogiston theory that was dominant in chemistry at that time, suggested that chlorine is dephlogisticated hydrochloric acid, that is, the oxide of hydrochloric acid.
Berthollet and Lavoisier suggested that chlorine is an oxide of the element muria, but attempts to isolate it remained unsuccessful until the work of Davy, who managed to decompose table salt into sodium and chlorine by electrolysis.
The name of the element comes from the Greek clwroz- "green".
Being in nature, receiving:
Natural chlorine is a mixture of two isotopes 35 Cl and 37 Cl. In the earth's crust, chlorine is the most common halogen. Since chlorine is very active, in nature it occurs only in the form of compounds in the minerals: halite NaCl, sylvite KCl, sylvinite KCl NaCl, bischofite MgCl 2 6H 2 O, carnallite KCl MgCl 2 6H 2 O, kainite KCl MgSO 4 ·3H 2 O. The largest reserves of chlorine are contained in the salts of the waters of the seas and oceans.
IN industrial scale chlorine is obtained together with sodium hydroxide and hydrogen by electrolysis of a solution of table salt:
2NaCl + 2H 2 O => H 2 + Cl 2 + 2NaOH
To recover chlorine from hydrogen chloride, which is a by-product during the industrial chlorination of organic compounds, the Deacon process is used (catalytic oxidation of hydrogen chloride with atmospheric oxygen):
4HCl + O 2 = 2H 2 O + 2Cl 2
Processes usually used in laboratories are based on the oxidation of hydrogen chloride with strong oxidizing agents (for example, manganese (IV) oxide, potassium permanganate, potassium dichromate):
2KMnO 4 + 16HCl = 5Cl 2 + 2MnCl 2 + 2KCl +8H 2 O
K 2 Cr 2 O 7 + 14HCl = 3Cl 2 + 2CrCl 3 + 2KCl + 7H 2 O
Physical properties:
Under normal conditions, chlorine is a yellow-green gas with a suffocating odor. Chlorine is noticeably soluble in water ("chlorine water"). At 20°C, 2.3 volumes of chlorine dissolve in one volume of water. Boiling point = -34°C; melting point = -101°C, density (gas, n.s.) = 3.214 g/l.
Chemical properties:
Chlorine is very active - it directly combines with almost all elements of the periodic table, metals and non-metals (except carbon, nitrogen, oxygen and inert gases). Chlorine is a very strong oxidizing agent, displacing less active non-metals (bromine, iodine) from their compounds with hydrogen and metals:
Cl 2 + 2HBr = Br 2 + 2HCl; Cl 2 + 2NaI = I 2 + 2NaCl
When dissolved in water or alkalis, chlorine dismutates, forming hypochlorous (and when heated, perchloric) and hydrochloric acids, or their salts.
Cl 2 + H 2 O HClO + HCl;
Chlorine interacts with many organic compounds, entering into substitution or addition reactions:
CH 3 -CH 3 + xCl 2 => C 2 H 6-x Cl x + xHCl
CH 2 =CH 2 + Cl 2 => Cl-CH 2 -CH 2 -Cl
C 6 H 6 + Cl 2 => C 6 H 6 Cl + HCl
Chlorine has seven oxidation states: -1, 0, +1, +3, +4, +5, +7.
The most important connections:
Hydrogen chloride HCl- a colorless gas that smokes in air due to the formation of fog droplets with water vapor. It has a pungent odor and severely irritates the respiratory tract. Contained in volcanic gases and waters, in gastric juice. Chemical properties depend on what state it is in (can be in a gaseous, liquid or solution state). The HCl solution is called hydrochloric acid. It is a strong acid and displaces weaker acids from their salts. Salts - chlorides- solid crystalline substances with high melting points.
Covalent chlorides- chlorine compounds with non-metals, gases, liquids or fusible solids that have characteristic acidic properties, usually easily hydrolyzed by water to form hydrochloric acid:
PCl 5 + 4H 2 O = H 3 PO 4 + 5HCl;
Chlorine(I) oxide Cl 2 O., a gas of brownish-yellow color with a pungent odor. Affects the respiratory organs. Easily dissolves in water, forming hypochlorous acid.
Hypochlorous acid HClO. Exists only in solutions. It is a weak and unstable acid. Easily decomposes into hydrochloric acid and oxygen. Strong oxidizing agent. Formed when chlorine dissolves in water. Salts - hypochlorites, low stability (NaClO*H 2 O decomposes explosively at 70 °C), strong oxidizing agents. Widely used for whitening and disinfection bleaching powder, mixed salt Ca(Cl)OCl
Chlorous acid HClO 2, in its free form is unstable, even in a dilute aqueous solution it quickly decomposes. Medium strength acid, salts - chlorites, as a rule, are colorless and highly soluble in water. Unlike hypochlorites, chlorites exhibit pronounced oxidizing properties only in an acidic environment. The greatest use (for bleaching fabrics and paper pulp) is sodium chlorite NaClO 2.
Chlorine(IV) oxide ClO 2, is a greenish-yellow gas with an unpleasant (pungent) odor, ...
Chloric acid, HClO 3 - in its free form is unstable: it disproportionates into ClO 2 and HClO 4. Salts - chlorates; of them highest value have sodium, potassium, calcium and magnesium chlorates. These are strong oxidizing agents and are explosive when mixed with reducing agents. Potassium chlorate ( Berthollet's salt) - KClO 3, was used to produce oxygen in the laboratory, but due to its high danger it was no longer used. Solutions of potassium chlorate were used as a weak antiseptic, external medicine for gargling.
Perchloric acid HClO 4, in aqueous solutions, perchloric acid is the most stable of all oxygen-containing chlorine acids. Anhydrous perchloric acid, which is obtained using concentrated sulfuric acid from 72% HClO 4, is not very stable. It is the strongest monoprotic acid (in aqueous solution). Salts - perchlorates, are used as oxidizers (solid propellant rocket engines).
Application:
Chlorine is used in many industries, science and household needs:
- In the production of polyvinyl chloride, plastic compounds, synthetic rubber;
- For bleaching fabric and paper;
- Production of organochlorine insecticides - substances that kill insects harmful to crops, but are safe for plants;
- For water disinfection - “chlorination”;
- Registered in the food industry as food additives E925;
- In the chemical production of hydrochloric acid, bleach, berthollet salt, metal chlorides, poisons, drugs, fertilizers;
- In metallurgy for the production of pure metals: titanium, tin, tantalum, niobium.
Biological role and toxicity:
Chlorine is one of the most important biogenic elements and is part of all living organisms. In animals and humans, chlorine ions are involved in maintaining osmotic balance; the chloride ion has an optimal radius for penetration through the cell membrane. Chlorine ions are vital for plants, participating in energy metabolism in plants, activating oxidative phosphorylation.
Chlorine in the form of a simple substance is poisonous; if it enters the lungs, it causes burns of lung tissue and suffocation. It has an irritating effect on the respiratory tract at a concentration in the air of about 0.006 mg/l (i.e., twice the threshold for the perception of the smell of chlorine). Chlorine was one of the first chemical agents used by Germany in World War I.
Korotkova Y., Shvetsova I.
HF Tyumen State University, 571 group.
Sources: Wikipedia: http://ru.wikipedia.org/wiki/Cl, etc.,
Website of the Russian Chemical Technical University named after. D.I. Mendeleev:
In nature, chlorine occurs in a gaseous state and only in the form of compounds with other gases. In conditions close to normal, it is a poisonous, caustic gas of a greenish color. Has more weight than air. Has a sweet smell. A chlorine molecule contains two atoms. In a calm state it does not burn, but at high temperatures it interacts with hydrogen, after which an explosion is possible. As a result, phosgene gas is released. Very poisonous. Thus, even at low concentrations in the air (0.001 mg per 1 dm 3) it can cause death. chlorine states that it is heavier than air, therefore, it will always be located near the floor in the form of a yellowish-green haze.
Historical facts
For the first time in practice, this substance was obtained by K. Scheeley in 1774 by combining hydrochloric acid and pyrolusite. However, only in 1810 P. Davy was able to characterize chlorine and establish that it is a separate chemical element.
It is worth noting that in 1772 he was able to obtain hydrogen chloride, a compound of chlorine and hydrogen, but the chemist was unable to separate these two elements.
Chemical characteristics of chlorine
Chlorine is a chemical element of the main subgroup of group VII of the periodic table. It is in the third period and has atomic number 17 (17 protons per atomic nucleus). Chemically active non-metal. Denoted by the letters Cl.
It is a typical representative of gases that have no color, but have a pungent, pungent odor. Typically toxic. All halogens are well diluted in water. When exposed to humid air, they begin to smoke.
The external electronic configuration of the Cl atom is 3s2Зр5. Therefore, in compounds, a chemical element exhibits oxidation levels of -1, +1, +3, +4, +5, +6 and +7. The covalent radius of the atom is 0.96 Å, the ionic radius of Cl- is 1.83 Å, the atomic electron affinity is 3.65 eV, the ionization level is 12.87 eV.
As stated above, chlorine is a fairly active non-metal, which makes it possible to create compounds with almost any metals (in some cases using heat or moisture, displacing bromine) and non-metals. In powder form, it reacts with metals only when exposed to high temperatures.
The maximum combustion temperature is 2250 °C. With oxygen it can form oxides, hypochlorites, chlorites and chlorates. All compounds containing oxygen become explosive when interacting with oxidizing substances. It is worth noting that they can explode arbitrarily, while chlorates explode only when exposed to any initiators.
Characteristics of chlorine by position in periodic table:
Simple substance;
. element of the seventeenth group of the periodic table;
. third period of the third row;
. seventh group of the main subgroup;
. atomic number 17;
. denoted by the symbol Cl;
. reactive non-metal;
. is in the halogen group;
. in conditions close to normal, it is a poisonous gas of a yellowish-green color with a pungent odor;
. a chlorine molecule has 2 atoms (formula Cl 2).
Physical properties of chlorine:
Boiling point: -34.04 °C;
. melting point: -101.5 °C;
. density in the gaseous state - 3.214 g/l;
. density of liquid chlorine (during the boiling period) - 1.537 g/cm3;
. density of solid chlorine - 1.9 g/cm 3 ;
. specific volume - 1.745 x 10 -3 l/g.
Chlorine: characteristics of temperature changes
In the gaseous state it tends to liquefy easily. At a pressure of 8 atmospheres and a temperature of 20 ° C, it looks like a greenish-yellow liquid. Has very high corrosive properties. As practice shows, this chemical element can maintain a liquid state up to a critical temperature (143 ° C), subject to increased pressure.
If it is cooled to a temperature of -32 ° C, it will change to liquid regardless of atmospheric pressure. With a further decrease in temperature, crystallization occurs (at -101 ° C).
Chlorine in nature
The earth's crust contains only 0.017% chlorine. The bulk is found in volcanic gases. As stated above, the substance has great chemical activity, as a result of which it is found in nature in compounds with other elements. However, many minerals contain chlorine. The characteristics of the element allow the formation of about a hundred different minerals. As a rule, these are metal chlorides.
Also, a large amount of it is found in the World Ocean - almost 2%. This is due to the fact that chlorides dissolve very actively and are carried by rivers and seas. The reverse process is also possible. The chlorine is washed back onto the shore, and then the wind carries it around the surrounding area. That is why its greatest concentration is observed in coastal zones. In the arid regions of the planet, the gas we are considering is formed through the evaporation of water, as a result of which salt marshes appear. About 100 million tons of this substance are mined annually in the world. Which, however, is not surprising, because there are many deposits containing chlorine. Its characteristics, however, largely depend on its geographical location.
Methods for producing chlorine
Today there are a number of methods for producing chlorine, of which the most common are the following:
1. Diaphragm. It is the simplest and least expensive. The brine solution in diaphragm electrolysis enters the anode space. Then it flows through the steel cathode grid into the diaphragm. It contains a small amount of polymer fibers. An important feature of this device is counterflow. It is directed from the anode space to the cathode space, which makes it possible to obtain chlorine and alkalis separately.
2. Membrane. The most energy efficient, but difficult to implement in an organization. Similar to diaphragm. The difference is that the anode and cathode spaces are completely separated by a membrane. Therefore, the output is two separate streams.
It is worth noting that the characteristics of the chemical element (chlorine) obtained by these methods will be different. The membrane method is considered to be more “clean”.
3. Mercury method with a liquid cathode. Compared to other technologies, this option allows you to obtain the purest chlorine.
The basic diagram of the installation consists of an electrolyzer and an interconnected pump and amalgam decomposer. The mercury pumped along with a solution of table salt serves as the cathode, and carbon or graphite electrodes serve as the anode. The operating principle of the installation is as follows: chlorine is released from the electrolyte, which is removed from the electrolyzer along with the anolyte. Impurities and residual chlorine are removed from the latter, re-saturated with halite and returned to electrolysis.
Industrial safety requirements and unprofitable production led to the replacement of the liquid cathode with a solid one.
Use of chlorine for industrial purposes
The properties of chlorine allow it to be actively used in industry. With the help of this chemical element obtain various (vinyl chloride, chloro-rubber, etc.), medications, disinfectants. But the largest niche occupied in the industry is the production of hydrochloric acid and lime.
Methods for purifying drinking water are widely used. Today they are trying to move away from this method, replacing it with ozonation, since the substance we are considering negatively affects the human body, and chlorinated water destroys pipelines. This is due to the fact that in the free state Cl has a detrimental effect on pipes made from polyolefins. However, most countries prefer the chlorination method.
Chlorine is also used in metallurgy. With its help, a number of rare metals (niobium, tantalum, titanium) are obtained. In the chemical industry, various organochlorine compounds are actively used to control weeds and for other agricultural purposes; the element is also used as a bleach.
Due to its chemical structure, chlorine destroys most organic and inorganic dyes. This is achieved by completely bleaching them. This result is possible only in the presence of water, because the process of discoloration occurs due to which it is formed after the breakdown of chlorine: Cl 2 + H 2 O → HCl + HClO → 2HCl + O. This method found application a couple of centuries ago and is still popular today.
The use of this substance for the production of organochlorine insecticides is very popular. These agricultural products kill harmful organisms while leaving the plants intact. A significant portion of all chlorine produced on the planet is used for agricultural needs.
It is also used in the production of plastic compounds and rubber. They are used to make wire insulation, stationery, equipment, and casings. household appliances etc. There is an opinion that rubbers obtained in this way are harmful to humans, but this is not confirmed by science.
It is worth noting that chlorine (the characteristics of the substance were described in detail by us earlier) and its derivatives, such as mustard gas and phosgene, are also used for military purposes to produce chemical warfare agents.
Chlorine as a prominent representative of non-metals
Nonmetals are simple substances that include gases and liquids. In most cases they perform worse electricity than metals, and have significant differences in physical and mechanical characteristics. With the help of a high level of ionization they are able to form covalent chemical compounds. Below we will give a description of a non-metal using chlorine as an example.
As mentioned above, this chemical element is a gas. Under normal conditions, it completely lacks properties similar to those of metals. Without outside help, it cannot interact with oxygen, nitrogen, carbon, etc. It exhibits its oxidizing properties in connections with simple substances and some complex ones. It is a halogen, which is clearly reflected in its chemical properties. In combination with other representatives of halogens (bromine, astatine, iodine), it displaces them. In the gaseous state, chlorine (its characteristics are direct confirmation of this) is highly soluble. Is an excellent disinfectant. It kills only living organisms, which makes it indispensable in agriculture and medicine.
Use as a poisonous substance
The characteristics of the chlorine atom make it possible to use it as a poisonous agent. Gas was first used by Germany on April 22, 1915, during the First World War, as a result of which about 15 thousand people died. At the moment it is not applicable.
Let's give brief description chemical element as an asphyxiant. Affects the human body through suffocation. First it irritates the upper respiratory tract and the mucous membrane of the eyes. A severe cough begins with attacks of suffocation. Further, penetrating into the lungs, the gas corrodes the lung tissue, which leads to edema. Important! Chlorine is a fast-acting substance.
Depending on the concentration in the air, symptoms vary. At low levels, a person experiences redness of the mucous membrane of the eyes and mild shortness of breath. A content of 1.5-2 g/m 3 in the atmosphere causes heaviness and sharp sensations in the chest, sharp pain in the upper respiratory tract. The condition may also be accompanied by severe lacrimation. After 10-15 minutes of being in a room with such a concentration of chlorine, severe lung burns and death occur. At denser concentrations, death is possible within a minute from paralysis of the upper respiratory tract.
Chlorine in the life of organisms and plants
Chlorine is found in almost all living organisms. The peculiarity is that it is not present in pure form, but in the form of compounds.
In animal and human organisms, chlorine ions maintain osmotic equality. This is due to the fact that they have the most suitable radius for penetration into membrane cells. Along with potassium ions, Cl regulates the water-salt balance. In the intestine, chlorine ions create a favorable environment for the action of proteolytic enzymes of gastric juice. Chlorine channels are found in many cells in our body. Through them, intercellular exchange of fluids occurs and the pH of the cell is maintained. About 85% of the total volume of this element in the body resides in the intercellular space. It is eliminated from the body through the urethra. Produced female body during breastfeeding.
At this stage of development, it is difficult to say unequivocally which diseases are provoked by chlorine and its compounds. This is due to the lack of research in this area.
Chlorine ions are also present in plant cells. He actively takes part in energy metabolism. Without this element, the process of photosynthesis is impossible. With its help, the roots actively absorb the necessary substances. But a high concentration of chlorine in plants can have a detrimental effect (slowing down the process of photosynthesis, stopping development and growth).
However, there are representatives of the flora who were able to “make friends” or at least get along with this element. The characteristics of a non-metal (chlorine) contain such an item as the ability of a substance to oxidize soils. In the process of evolution, the above-mentioned plants, called halophytes, occupied empty salt marshes, which were empty due to an overabundance of this element. They absorb chlorine ions, and then get rid of them with the help of leaf fall.
Transportation and storage of chlorine
There are several ways to move and store chlorine. The characteristics of the element require special high-pressure cylinders. Such containers have an identification marking - a vertical green line. Cylinders must be thoroughly washed monthly. When chlorine is stored for a long time, a very explosive precipitate is formed - nitrogen trichloride. Failure to comply with all safety rules may result in spontaneous ignition and explosion.
Chlorine study
Future chemists should know the characteristics of chlorine. According to the plan, 9th graders can even conduct laboratory experiments with this substance based on basic knowledge of the discipline. Naturally, the teacher is obliged to provide safety instructions.
The work procedure is as follows: you need to take a flask with chlorine and pour small metal shavings into it. In flight, the shavings will flare up with bright light sparks and at the same time light white SbCl 3 smoke will form. When tin foil is immersed in a vessel with chlorine, it will also spontaneously ignite, and fiery snowflakes will slowly fall to the bottom of the flask. During this reaction, a smoky liquid is formed - SnCl 4. When iron filings are placed in a vessel, red “drops” will form and red FeCl 3 smoke will appear.
Along with practical work, theory is repeated. In particular, such a question as the characteristics of chlorine by position in the periodic table (described at the beginning of the article).
As a result of experiments, it turns out that the element actively reacts to organic compounds. If you place cotton wool, previously soaked in turpentine, in a jar of chlorine, it will instantly ignite and soot will suddenly fall out of the flask. Sodium smolders spectacularly with a yellowish flame, and salt crystals appear on the walls of the chemical container. Students will be interested to know that, while still a young chemist, N. N. Semenov (later laureate Nobel Prize), having carried out such an experiment, collected salt from the walls of the flask and, sprinkled it on the bread, ate it. Chemistry turned out to be right and did not let the scientist down. As a result of the experiment carried out by the chemist, ordinary table salt actually turned out!
Cl 2 at vol. T - yellow-green gas with a sharp suffocating odor, 2.5 times heavier than air, slightly soluble in water (~ 6.5 g/l); X. R. in non-polar organic solvents. It is found in free form only in volcanic gases.
Methods of obtaining
Based on the oxidation process of Cl - anions
2Cl - - 2e - = Cl 2 0
Industrial
Electrolysis of aqueous solutions of chlorides, more often NaCl:
2NaCl + 2H 2 O = Cl 2 + 2NaOH + H 2
Laboratory
Oxidation of conc. HCI with various oxidizing agents:
4HCI + MnO 2 = Cl 2 + MnCl 2 + 2H 2 O
16HCl + 2KMnO 4 = 5Cl 2 + 2MnCl 2 + 2KCl + 8H 2 O
6HCl + KClO 3 = 3Cl 2 + KCl + 3H 2 O
14HCl + K 2 Cr 2 O 7 = 3Cl 2 + 2CrCl 3 + 2KCl + 7H 2 O
Chemical properties
Chlorine is a very strong oxidizing agent. Oxidizes metals, non-metals and complex substances, turning into very stable Cl - anions:
Cl 2 0 + 2e - = 2Cl -
Reactions with metals
Active metals in an atmosphere of dry chlorine gas ignite and burn; in this case, metal chlorides are formed.
Cl 2 + 2Na = 2NaCl
3Cl 2 + 2Fe = 2FeCl 3
Low-active metals are more easily oxidized by wet chlorine or its aqueous solutions:
Cl 2 + Cu = CuCl 2
3Cl 2 + 2Au = 2AuCl 3
Reactions with nonmetals
Chlorine does not directly interact only with O 2, N 2, C. Reactions with other non-metals occur under different conditions.
Nonmetal halides are formed. The most important reaction is interaction with hydrogen.
Cl 2 + H 2 = 2HC1
Cl 2 + 2S (melt) = S 2 Cl 2
ЗCl 2 + 2Р = 2РCl 3 (or РCl 5 - in excess of Cl 2)
2Cl 2 + Si = SiCl 4
3Cl 2 + I 2 = 2ICl 3
Displacement of free non-metals (Br 2, I 2, N 2, S) from their compounds
Cl 2 + 2KBr = Br 2 + 2KCl
Cl 2 + 2KI = I 2 + 2KCl
Cl 2 + 2HI = I 2 + 2HCl
Cl 2 + H 2 S = S + 2HCl
3Cl 2 + 2NH 3 = N 2 + 6HCl
Disproportionation of chlorine in water and aqueous solutions of alkalis
As a result of self-oxidation-self-reduction, some chlorine atoms are converted into Cl - anions, while others in a positive oxidation state are included in the ClO - or ClO 3 - anions.
Cl 2 + H 2 O = HCl + HClO hypochlorous acid
Cl 2 + 2KOH = KCl + KClO + H 2 O
3Cl 2 + 6KOH = 5KCl + KClO 3 + 3H 2 O
3Cl 2 + 2Ca(OH) 2 = CaCl 2 + Ca(ClO) 2 + 2H 2 O
These reactions are important because they lead to the production of oxygen chlorine compounds:
KClO 3 and Ca(ClO) 2 - hypochlorites; KClO 3 - potassium chlorate (Berthollet salt).
Interaction of chlorine with organic substances
a) replacement of hydrogen atoms in OM molecules
b) attachment of Cl 2 molecules at the site of rupture of multiple carbon-carbon bonds
H 2 C=CH 2 + Cl 2 → ClH 2 C-CH 2 Cl 1,2-dichloroethane
HC≡CH + 2Cl 2 → Cl 2 HC-CHCl 2 1,1,2,2-tetrachloroethane
Hydrogen chloride and hydrochloric acid
Hydrogen chloride gas
Physical and chemical properties
HCl - hydrogen chloride. At rev. T - colorless. a gas with a pungent odor, liquefies quite easily (mp -114°C, bp -85°C). Anhydrous HCl, both in gaseous and liquid states, is non-electrically conductive and chemically inert towards metals, metal oxides and hydroxides, as well as many other substances. This means that in the absence of water, hydrogen chloride does not exhibit acidic properties. Only at very high temperatures does gaseous HCl react with metals, even such low-active ones as Cu and Ag.
The reducing properties of the chloride anion in HCl also appear to a small extent: it is oxidized by fluorine at vol. T, and also at high T (600°C) in the presence of catalysts, it reacts reversibly with oxygen:
2HCl + F 2 = Cl 2 + 2HF
4HCl + O 2 = 2Сl 2 + 2H 2 O
Gaseous HCl is widely used in organic synthesis (hydrochlorination reactions).
Methods of obtaining
1. Synthesis from simple substances:
H 2 + Cl 2 = 2HCl
2. Formed as a by-product during chlorination of hydrocarbons:
R-H + Cl 2 = R-Cl + HCl
3. In the laboratory it is obtained by the action of conc. H 2 SO 4 for chlorides:
H 2 SO 4 (conc.) + NaCl = 2HCl + NaHSO 4 (with low heating)
H 2 SO 4 (conc.) + 2NaCl = 2HCl + Na 2 SO 4 (with very high heating)
Aqueous solution of HCl - strong acid (hydrochloric or hydrochloric)
HCl is very soluble in water: at vol. In 1 liter of H 2 O ~ 450 liters of gas are dissolved (dissolution is accompanied by the release of a significant amount of heat). The saturated solution has a mass fraction of HCl equal to 36-37%. This solution has a very pungent, suffocating odor.
HCl molecules in water almost completely disintegrate into ions, i.e. an aqueous solution of HCl is a strong acid.
Chemical properties of hydrochloric acid
1. HCl dissolved in water exhibits all the general properties of acids due to the presence of H + ions
HCl → H + + Cl -
Interaction:
a) with metals (up to H):
2HCl 2 + Zn = ZnCl 2 + H 2
b) with basic and amphoteric oxides:
2HCl + CuO = CuCl 2 + H 2 O
6HCl + Al 2 O 3 = 2AlCl 3 + ZN 2 O
c) with bases and amphoteric hydroxides:
2HCl + Ca(OH) 2 = CaCl 2 + 2H 2 O
3HCl + Al(OH) 3 = AlCl 3 + ZH 2 O
d) with salts of weaker acids:
2HCl + CaCO 3 = CaCl 2 + CO 2 + H 3 O
HCl + C 6 H 5 ONa = C 6 H 5 OH + NaCl
e) with ammonia:
HCl + NH 3 = NH 4 Cl
Reactions with strong oxidizing agents F 2, MnO 2, KMnO 4, KClO 3, K 2 Cr 2 O 7. The Cl - anion is oxidized to free halogen:
2Cl - - 2e - = Cl 2 0
For reaction equations, see "Production of chlorine." Of particular importance is the ORR between hydrochloric and nitric acids:
Reactions with organic compounds
Interaction:
a) with amines (as organic bases)
R-NH 2 + HCl → + Cl -
b) with amino acids (as amphoteric compounds)
Chlorine oxides and oxoacids
Acidic oxides
Acids
Salts
Chemical properties
1. All chlorine oxoacids and their salts are strong oxidizing agents.
2. Almost all compounds decompose when heated due to intramolecular oxidation-reduction or disproportionation.
Bleaching powder
Chloric (bleaching) lime is a mixture of hypochlorite and calcium chloride, has a bleaching and disinfectant effect. Sometimes considered as an example of a mixed salt containing simultaneously the anions of two acids:
Javel water
Aqueous solution of potassium chloride and hapochlorite KCl + KClO + H 2 O
