Chlorine: properties, application, obtaining. Being in nature

In 1774, Carl Scheele, a chemist from Sweden, first obtained chlorine, but it was believed that this was not a separate element, but a type of hydrochloric acid (calorizator). Elemental chlorine was obtained at the beginning of the 19th century by G. Davy, who decomposed table salt into chlorine and sodium by electrolysis.

Chlorine (from the Greek χλωρός - green) is an element of the XVII group of the periodic table of chemical elements of D.I. Mendeleev, has an atomic number of 17 and an atomic mass of 35.452. The accepted designation Cl (from the Latin Chlorum).

Being in nature

Chlorine is the most common halogen in the earth's crust, most often in the form of two isotopes. Due to its chemical activity, it is found only in the form of compounds of many minerals.

Chlorine is a poisonous yellow-green gas with a pungent odor and a sweetish taste. It was chlorine that, after its discovery, was proposed to be called halogen, it is included in the group of the same name as one of the most chemically active non-metals.

Daily requirement for chlorine

Normally, a healthy adult should receive 4-6 g of chlorine per day, the need for it increases with active physical exertion or hot weather (with increased sweating). Usually, the body receives the daily norm from food with a balanced diet.

The main supplier of chlorine to the body is table salt - especially if it is not subjected to heat treatment, so it is better to salt already prepared dishes. Also contain chlorine, seafood, meat, and, and,.

Interaction with others

The acid-base and water balance of the body is regulated by chlorine.

Signs of a lack of chlorine

The lack of chlorine is caused by processes that lead to dehydration of the body - severe sweating in the heat or during physical exertion, vomiting, diarrhea and some diseases of the urinary system. Signs of a lack of chlorine are lethargy and drowsiness, muscle weakness, pronounced dry mouth, loss of taste, lack of appetite.

Signs of excess chlorine

Signs of excess chlorine in the body are: increased blood pressure, dry cough, pain in the head and chest, pain in the eyes, watery eyes, disorders of the gastrointestinal tract. As a rule, an excess of chlorine can be caused by drinking ordinary tap water, which goes through the process of disinfection with chlorine and occurs in workers in industries that are directly related to the use of chlorine.

Chlorine in the human body:

• regulates water and acid-base balance,
• removes fluid and salts from the body in the process of osmoregulation,
• stimulates normal digestion,
• normalizes the state of erythrocytes,
• cleanses the liver of fat.

The main use of chlorine is the chemical industry, where it is used to make polyvinyl chloride, polystyrene foam, packaging materials, as well as chemical warfare agents and fertilizers for plants. Disinfection of drinking water with chlorine is practically the only available way to purify water.

Chlorine- an element of the 3rd period and VII A-group of the Periodic system, serial number 17. The electronic formula of the atom is [ 10 Ne ] 3s 2 Зр 5, characteristic oxidation states 0, -1, + 1, +5 and +7. The most stable state is Cl -1 . Chlorine oxidation state scale:

7 - Cl 2 O 7, ClO 4 -, HClO 4, KClO 4

5 - ClO 3 -, HClO 3, KClO 3

1 - Cl 2 O , ClO - , HClO , NaClO , Ca(ClO) 2

- 1 - Cl - , HCl, KCl , PCl 5

Chlorine has a high electronegativity (2.83) and exhibits non-metallic properties. It is part of many substances - oxides, acids, salts, binary compounds.

In nature - twelfth by chemical abundance, the element (fifth among non-metals). It occurs only in a chemically bound form. The third element in content in natural waters (after O and H), especially a lot of chlorine in sea water (up to 2% by weight). A vital element for all organisms.

Chlorine C1 2. Simple substance. Yellow-green gas with a pungent, suffocating odour. The Cl 2 molecule is non-polar, contains a C1-C1 σ-bond. Thermally stable, non-combustible in air; mixture with hydrogen explodes in the light (hydrogen burns in chlorine):

Cl 2 +H 2 ⇌HCl

It is highly soluble in water, undergoes dismutation in it by 50% and completely - in an alkaline solution:

Cl 2 0 +H 2 O ⇌HCl I O + HCl -I

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

3Cl 2 + 6NaOH (gor) \u003d NaClO 3 + 5NaCl + H 2 O

A solution of chlorine in water is called chlorine water, in the light, HClO acid decomposes into HCl and atomic oxygen O 0, therefore, "chlorine water" must be stored in a dark bottle. The presence of HClO acid in “chlorine water” and the formation of atomic oxygen explain its strong oxidizing properties: for example, many dyes become colorless in wet chlorine.

Chlorine is a very strong oxidizing agent with respect to metals and non-metals:

Cl 2 + 2Na = 2NaCl 2

ЗСl 2 + 2Fe→2FeСl 3 (200 °C)

Cl 2 + Se \u003d SeCl 4

Cl 2 + Pb → PbCl 2 (300°FROM)

5Cl 2 +2P→2PCl 5 (90 °C)

2Cl 2 +Si→SiCl 4 (340 °С)

Reactions with compounds of other halogens:

a) Cl 2 + 2KVg (P) = 2KSl + Br 2 (boiling)

b) Сl 2 (week) + 2КI (р) = 2КCl + I 2 ↓

ZCl (ex.) + 3H 2 O + KI \u003d 6HCl + KIO 3 (80 °С)

Qualitative reaction- the interaction of a lack of CL 2 with KI (see above) and the detection of iodine by blue staining after adding a starch solution.

Receipt chlorine in industry:

2NаСl (melt) → 2Nа + Сl 2 (electrolysis)

2NaCl+ 2Н 2 O→Н 2 + Cl 2+ 2NаOH (electrolysis)

and in laboratories:

4HCl (conc.) + MnO 2 \u003d Cl 2 + MnCl 2 + 2H 2 O

(similarly with the participation of other oxidizing agents; see the reactions for HCl and NaCl for more details).

Chlorine is a product of the main chemical production, used to produce bromine and iodine, chlorides and oxygen-containing derivatives, for paper bleaching, as a disinfectant for drinking water. Poisonous.

Hydrogen chloride HC l . Anoxic acid. A colorless gas with a pungent odor, heavier than air. The molecule contains a covalent σ-bond H - Cl. Thermally stable. Let's very well dissolve in water; dilute solutions are called hydrochloric acid, and a fuming concentrated solution (35-38%) - hydrochloric acid(the name was given by the alchemists). Strong acid in solution, neutralized by alkalis and ammonia hydrate. A strong reducing agent in a concentrated solution (due to Cl - I), a weak oxidizing agent in a dilute solution (due to H I). An integral part of "royal vodka".

A qualitative reaction to the Cl ion is the formation of white precipitates of AgCl and Hg 2 Cl 2, which are not transferred into solution by the action of dilute nitric acid.

Hydrogen chloride serves as a raw material in the production of chlorides, organochlorine products, is used (in the form of a solution) in the etching of metals, the decomposition of minerals and ores. Equations of the most important reactions:

HCl (dil.) + NaOH (dil.) \u003d NaCl + H 2 O

Hcl (razb.) + NH 3 H 2 O \u003d NH 4 Cl + H 2 O

4HCl (conc., horizon) + MO 2 \u003d MCl 2 + Cl 2 + 2H 2 O (M = Mn, Pb)

16HCl (conc., horizon) + 2KMnO 4 (t) \u003d 2MnCl 2 + 5Cl 2 + 8H 2 O + 2KCl

14HCl (conc.) + K 2 Cr 2 O 7 (t) \u003d 2СrCl 3 + ZCl 2 + 7H 2 O + 2KSl

6HCl (conc.) + KClO 3 (T) \u003d KCl + ZCl 2 + 3H 2 O (50-80 °С)

4HCl (conc.) + Ca (ClO) 2 (t) \u003d CaCl 2 + 2Cl 2 + 2H 2 O

2HCl (razb.) + M \u003d MCl 2 + H 2 (M = Re, 2p)

2HCl (razb.) + MSO 3 \u003d MCl 2 + CO 2 + H 2 O (M = Ca, Va)

Hcl (razb.) + AgNO 3 \u003d HNO 3 + AgCl ↓

Obtaining Hcl in industry - burning H 2 in Cl 2 (see), in the laboratory - displacement from chlorides with sulfuric acid:

NaCl (t) + H 2 SO4 (conc.) = NaHSO 4 + NAl(50 °C)

2NaCl (t) + H 2 SO 4 (conc.) = Na 2 SO 4 + 2HCl(120 °C)

chlorides

Sodium chloride Na Cl . Anoxic salt. household name salt. White, slightly hygroscopic. Melts and boils without decomposition. Moderately soluble in water, solubility slightly depends on temperature, the solution has a characteristic salty taste. Does not undergo hydrolysis. Weak reducer. Enters into ion exchange reactions. It is subjected to electrolysis in melt and solution.

It is used to produce hydrogen, sodium and chlorine, soda, caustic soda and hydrogen chloride, as a component of cooling mixtures, a food product and a preservative.

In nature - the main part of rock salt deposits, or halite, and sylvinite(together with KCl), brines of salt lakes, mineral impurities of sea water (NaCl content = 2.7%). In industry, it is obtained by evaporating natural brines.

Equations of the most important reactions:

2NaCl (t) + 2H 2 SO 4 (conc.) + MnO 2 (t) \u003d Cl 2 + MnSO 4 + 2H 2 O + Na 2 SO 4 (100 °C)

10NaCl (t) + 8H 2 SO 4 (conc.) + 2KMnO 4 (t) \u003d 5Cl 2 + 2MnSO 4 + 8H 2 O + 5Na 2 SO 4 + K 2 SO 4 (100°C)

6NaCl (T) + 7H 2 SO 4 (conc.) + K 2 Cr 2 O 7 (t) \u003d 3Cl 2 + Cr 2 (SO 4) 3 + 7H 2 O + ZNa 2 SO 4 + K 2 SO 4 (100 °C)

2NaCl (t) + 4H 2 SO 4 (conc.) + PbO 2 (t) \u003d Cl 2 + Pb (HSO 4) 2 + 2H 2 O + 2NaHSO 4 (50 °C)

NaCl (razb.) + AgNO 3 \u003d NaNO 3 + AgCl ↓

NaCl (l) → 2Na + Cl 2 (850°С, electrolysis)

2NaCl + 2H 2 O → H 2 + Cl 2 + 2NaOH (electrolysis)

2NaCl (p, 20%) → Cl 2 + 2 Na(Hg) "amalgam"(electrolysis, onhg-cathode)

Potassium chloride KCl . Anoxic salt. White, non-hygroscopic. Melts and boils without decomposition. Sparingly soluble in water, the solution has a bitter taste, no hydrolysis. Enters into ion exchange reactions. It is used as a potash fertilizer to obtain K, KOH and Cl 2 . In nature, the main component (along with NaCl) of deposits sylvinite.

The equations of the most important reactions are the same as those for NaCl.

Calcium chloride CaCl 2 . Anoxic salt. White, melts without decomposition. Disperses in the air due to the vigorous absorption of moisture. Forms a crystalline CaCl 2 6H 2 O with a dehydration temperature of 260 °C. Let's well dissolve in water, there is no hydrolysis. Enters into ion exchange reactions. It is used for drying gases and liquids, preparing cooling mixtures. A component of natural waters, an integral part of their "permanent" hardness.

Equations of the most important reactions:

CaCl 2 (T) + 2H 2 SO 4 (conc.) \u003d Ca (HSO 4) 2 + 2HCl (50 °C)

CaCl 2 (T) + H 2 SO 4 (conc.) \u003d CaSO 4 ↓ + 2HCl (100 °C)

CaCl 2 + 2NaOH (conc.) \u003d Ca (OH) 2 ↓ + 2NaCl

ЗСаСl 2 + 2Na 3 RO 4 \u003d Ca 3 (PO 4) 2 ↓ + 6NaCl

CaCl 2 + K 2 CO 3 \u003d CaCO 3 ↓ + 2KSl

CaCl 2 + 2NaF \u003d CaF 2 ↓ + 2NaCl

CaCl 2 (g) → Ca + Cl 2 (electrolysis, 800°С)

Receipt:

CaCO 3 + 2HCl = CaCl 2 + CO 3 + H 2 O

Aluminum chloride AlCl 3 . Anoxic salt. White, fusible, highly volatile. The pair consists of AlCl 3 covalent monomers (triangular structure, sp 2 hybridization, prevail at 440-800 ° C) and Al 2 Cl 6 dimers (more precisely, Cl 2 AlCl 2 AlCl 2, the structure is two tetrahedra with a common edge, sp 3 -hybridization, prevail at 183-440 °C). Hygroscopic, smokes in air. Forms a crystalline hydrate that decomposes when heated. It is highly soluble in water (with a strong exo-effect), completely dissociates into ions, creates a strongly acidic environment in solution due to hydrolysis. Reacts with alkalis, ammonia hydrate. It is restored during the electrolysis of the melt. Enters into ion exchange reactions.

Qualitative reaction on the Al 3+ ion - the formation of a precipitate of AlPO 4, which is transferred into a solution with concentrated sulfuric acid.

It is used as a raw material in aluminum production, as a catalyst in organic synthesis and in oil cracking, as a chlorine carrier in organic reactions. Equations of the most important reactions:

AlCl 3 . 6H 2 O → AlCl (OH) 2 (100-200°С, —HCl, H 2 O) →Al 2 O 3 (250-450°С,-HCl,H2O)

AlCl 3 (t) + 2H 2 O (moisture) \u003d AlCl (OH) 2 (t) + 2HCl (White smoke")

AlCl 3 + ZNaOH (razb.) \u003d Al (OH) 3 (amorphous) ↓ + ZNaCl

AlCl 3 + 4NaOH (conc.) = Na[Al(OH) 4] + ZNaCl

AlCl 3 + 3 (NH 3. H 2 O) (conc.) \u003d Al (OH) 3 (amorphous) + ZNH 4 Cl

AlCl 3 + 3 (NH 3 H 2 O) (conc.) \u003d Al (OH) ↓ + ZNH 4 Cl + H 2 O (100°C)

2Al 3+ + 3H 2 O + ZSO 2- 3 \u003d 2Al (OH) 3 ↓ + ZSO 2 (80°C)

2Al 3+ \u003d 6H 2 O + 3S 2- \u003d 2Al (OH) 3 ↓+ 3H 2 S

Al 3+ + 2HPO 4 2- - AlPO 4 ↓ + H 2 PO 4 -

2AlCl 3 → 2Al + 3Cl 2 (electrolysis, 800 °C ,in the meltNasl)

Receipt AlCl in industry and - chlorination of kaolin, alumina or bauxite in the presence of coke:

Al 2 O 3 + 3C (coke) + 3Cl 2 = 2AlCl 3 + 3CO (900 °С)

Ferric chloride( II ) F EU l 2 . Anoxic salt. White (blue-green hydrate), hygroscopic. Melts and boils without decomposition. With strong heating, it is volatile in a stream of HCl. Fe-Cl bonds are predominantly covalent, the pair consists of FeCl 2 monomers (linear structure, sp-hybridization) and Fe 2 Cl 4 dimers. Sensitive to atmospheric oxygen (darkens). Let's well dissolve in water (with strong exo-effect), completely dissociates on ions, is slightly hydrolyzed on cation. When the solution is boiled, it decomposes. Reacts with acids, alkalis, ammonia hydrate. Typical restorer. It enters into reactions of ion exchange and complex formation.

It is used for the synthesis of FeCl and Fe 2 O 3 , as a catalyst in organic synthesis, a component of medicines against anemia.

Equations of the most important reactions:

FeCl 2 4H 2 O \u003d FeCl 2 + 4H 2 O (220 °С, in atm.N 2 )

FeCl 2 (conc.) + H 2 O \u003d FeCl (OH) ↓ + Hcl (boiling)

FeCl 2 (t) + H 2 SO 4 (conc.) \u003d FeSO 4 + 2HCl (boiling)

FeCl 2 (t) + 4HNO 3 (conc.) \u003d Fe (NO 3) 3 + NO 2 + 2HCl + H 2 O

FeCl 2 + 2NaOH (razb.) \u003d Fe (OH) 2 ↓ + 2NaCl (in atm.N 2 )

FeCl 2 + 2 (NH 3 . H 2 O) (conc.) \u003d Fe (OH) 2 ↓ + 2NH 4 Cl (80 °С)

FeCl 2 + H 2 \u003d 2HCl + Fe (extra pure, above 500 °C)

4FeCl 2 + O 2 (air) → 2Fe(Cl)O + 2FeCl 3 (t)

2FeCl 2(p) + Cl 2 (ex.) = 2FeCl 3(p)

5Fe 2+ + 8H + + MnO - 4 \u003d 5Fe 3+ + Mn 2+ + 4H 2 O

6Fe 2+ + 14H + + Cr 2 O 7 2- \u003d 6Fe 3+ + 2Cr 3+ + 7H 2 O

Fe 2+ + S 2- (razb.) \u003d FeS ↓

2Fe 2+ + H 2 O + 2CO 3 2- (razb.) \u003d Fe 2 CO 3 (OH) 2 ↓ + CO 2

FeCl 2 → Fe ↓ + Cl 2 (90°С, diluted with HCl, electrolysis)

Get e: interaction of Fe with hydrochloric acid:

Fe + 2HCl = FeCl 2+ H 2

(in industry hydrogen chloride is used and the process is carried out at 500 ° C).

Ferric chloride( III ) F EU l 3 . Anoxic salt. Black-brown (dark red in transmitted light, green in reflected), dark yellow hydrate. When melted, it turns into a red liquid. Very volatile, decomposes on strong heating. Fe-Cl bonds are predominantly covalent. The vapor consists of FeCl 3 monomers (triangular structure, sp 2 hybridization, dominate above 750 ° C) and Fe 2 Cl 6 dimers (more precisely, Cl 2 FeCl 2 FeCl 2, the structure is two tetrahedra with a common edge, sp 3 hybridization, dominate at 316-750 °C). FeCl crystalline hydrate. 6H 2 O has the structure of Cl 2H 2 O. Let's dissolve well in water, the solution is colored yellow; highly hydrolyzed at the cation. Decomposes in hot water, reacts with alkalis. Weak oxidizing and reducing agent.

It is used as a chlorine agent, a catalyst in organic synthesis, a mordant in dyeing fabrics, a coagulant in the purification of drinking water, an etchant for copper plates in electroplating, a component of hemostatic preparations.

Equations of the most important reactions:

FeCl 3 6H 2 O \u003d Cl + 2H 2 O (37 °C)

2 (FeCl 8 6H 2 O) \u003d Fe 2 O 3 + 6HCl + 9H 2 O (above 250 °C)

FeCl 3 (10%) + 4H 2 O \u003d Cl - + + (yellow)

2FeCl3 (conc.) + 4H 2 O \u003d + (yellow) + - (bts.)

FeCl 3 (razb., conc.) + 2H 2 O → FeCl (OH) 2 ↓ + 2HCl (100 °C)

FeCl 3 + 3NaOH (razb.) \u003d FeO (OH) ↓ + H 2 O + 3NaCl (50 °C)

FeCl 3 + 3 (NH 3 H 2 O) (conc, horizon) \u003d FeO (OH) ↓ + H 2 O + 3NH 4 Cl

4FeCl 3 + 3O 2 (air) \u003d 2Fe 2 O 3 + 3Cl 2 (350-500 °С)

2FeCl 3(p) + Cu → 2FeCl 2 + CuCl 2

ammonium chloride N H 4 Cl . Anoxic salt, technical name ammonia. White, volatile, thermally unstable. Let's well dissolve in water (with noticeable endo-effect, Q = -16 kJ), it is hydrolyzed on cation. It decomposes with alkalis when the solution is boiled, converts magnesium and magnesium hydroxide into solution. Enters into a reaction of mutation with nitrates.

Qualitative reaction on the NH 4 + ion - the release of NH 3 when boiled with alkalis or when heated with slaked lime.

It is used in inorganic synthesis, in particular, to create a weakly acidic environment, as a component of nitrogen fertilizers, dry galvanic cells, when soldering copper and tinning steel products.

Equations of the most important reactions:

NH 4 Cl (t) ⇌ NH 3 (g) + HCl (g) (above 337.8 °C)

NH 4 Cl + NaOH (sat.) = NaCl + NH 3 + H 2 O (100 °C)

2NH 4 Cl (T) + Ca (OH) 2 (t) \u003d 2NH 3 + CaCl 2 + 2H 2 O (200°C)

2NH 4 Cl (conc.) + Mg \u003d H 2 + MgCl 2 + 2NH 3 (80°C)

2NH 4 Cl (conc., horizon) + Mg (OH) 2 = MgCl 2 + 2NH 3 + 2H 2 O

NH + (sat.) + NO - 2 (sat.) \u003d N 2 + 2H 2 O (100°C)

NH 4 Cl + KNO 3 \u003d N 2 O + 2H 2 O + KCl (230-300 °С)

Receipt: interaction of NH 3 with HCl in the gas phase or NH 3 H 2 O with HCl in solution.

Calcium hypochlorite Ca(C l O) 2 . Salt of hypochlorous acid HClO. White, decomposes without melting when heated. Let's well dissolve in cold water (a colorless solution is formed), it is hydrolyzed on anion. Reactive, completely decomposed by hot water, acids. Strong oxidizer. When standing, the solution absorbs carbon dioxide from the air. Is an active part chlorine (bleach) lime - mixtures of uncertain composition with CaCl 2 and Ca(OH) 2 . Equations of the most important reactions:

Ca (ClO) 2 \u003d CaCl 2 + O 2 (180 °С)

Ca (ClO) 2 (t) + 4HCl (conc.) \u003d CaCl + 2Cl 2 + 2H 2 O (80 °С)

Ca (ClO) 2 + H 2 O + CO 2 \u003d CaCO 3 ↓ + 2HClO (in the cold)

Ca (ClO) 2 + 2H 2 O 2 (razb.) \u003d CaCl 2 + 2H 2 O + 2O 2

Receipt:

2Ca(OH) 2 (suspension) + 2Cl 2 (g) \u003d Ca (ClO) 2 + CaCl 2 + 2H 2 O

Potassium chlorate KS lo 3 . Salt of chloric acid HclO 3, the most famous salt of oxygen-containing acids of chlorine. technical name - Berthollet's salt(named after its discoverer K.-L. Berthollet, 1786). White, melts without decomposition, decomposes upon further heating. Let's well dissolve in water (a colorless solution is formed), there is no hydrolysis. Decomposed by concentrated acids. Strong oxidizing agent when fused.

It is used as a component of explosive and pyrotechnic mixtures, match heads, in the laboratory - a solid source of oxygen.

Equations of the most important reactions:

4KSlO 3 \u003d ZKSlO 4 + KCl (400 °C)

2KSlO 3 \u003d 2KSl + 3O 2 (150-300 °C, cat. MpO 2 )

KClO 3 (T) + 6HCl (conc.) \u003d KCl + 3Cl 2 + ZN 2 O (50-80 °С)

3KSlO 3 (T) + 2H 2 SO 4 (conc., horizon) \u003d 2ClO 2 + KClO 4 + H 2 O + 2KHSO 4

(chlorine dioxide explodes in the light: 2Clo2(G)\u003d Cl 2 + 2O 2 )

2KSlO 3 + E 2 (ex.) \u003d 2KEO 3 + Cl 2 (in section HNO 3 , E = Br, I)

KClO 3 + H 2 O → H 2 + KClO 4 (Electrolysis)

Receipt KClO 3 in industry - electrolysis of a hot KCl solution (KClO 3 product is released at the anode):

KCl + 3H 2 O → H 2 + KClO 3 (40-60°C, Electrolysis)

Potassium bromide KV r . Anoxic salt. White, non-hygroscopic, melts without decomposition. Let's well dissolve in water, there is no hydrolysis. Reducing agent (weaker than

Qualitative reaction on the Br ion - the displacement of bromine from the KBr solution with chlorine and the extraction of bromine into an organic solvent, for example, CCl 4 (as a result, the aqueous layer becomes colorless, the organic layer turns brown).

It is used as a component of etchants for engraving on metals, an integral part of photographic emulsions, a medicinal product.

Equations of the most important reactions:

2KVr (t) + 2H 2 SO 4 (CONC., mountains) + MnO 2 (t) \u003d Br 2 + MnSO 4 + 2H 2 O + K 2 SO 4

5Br - + 6H + + BrO 3 - \u003d 3Br 2 + 3H 2 O

Вr — + Аg + =АgВr↓

2KVr (p) + Cl 2 (G) \u003d 2KSl + Br 2 (p)

KBr + 3H 2 O → 3H 2 + KBrO 3 (60-80 °С, electrolysis)

Receipt:

K 2 CO 3 + 2HBr = 2KVr+ CO 2 + H 2 O

Potassium iodide K I . Anoxic salt. White, non-hygroscopic. Turns yellow when exposed to light. Let's well dissolve in water, there is no hydrolysis. Typical restorer. An aqueous solution of KI readily dissolves I 2 due to complexation.

quality the reaction to the I ion is the displacement of iodine from the KI solution by a lack of chlorine and the extraction of iodine into an organic solvent, for example CCl 4 (as a result, the aqueous layer becomes colorless, the organic layer turns purple).

Equations of the most important reactions:

10I - + 16H + + 2MnO 4 - \u003d 5I 2 ↓ + 2Mn 2+ + 8H 2 O

6I - + 14H + + Cr 2 O 7 2- \u003d 3I 2 ↓ + 2Cr 3+ + 7H 2 O

2I - + 2H + + H 2 O 2 (3%) \u003d I 2 ↓ + 2H 2 O

2I - + 4H + + 2NO 2 - \u003d I 2 ↓ + 2NO + 2H 2 O

5I - + 6H + + IO 3 - \u003d 3I 2 + 3H 2 O

I - + Ag + = AgI (yellow.) ↓

2KI (r) + Cl 2 (r) (week) \u003d 2KSl + I 2 ↓

KI + 3H 2 O + 3Cl 2 (p) (ex.) \u003d KIO 3 + 6HCl (80°C)

KI (P) + I 2 (t) \u003d K) (P) (short) ("iodine water")

KI + 3H 2 O → 3H 2 + KIO 3 (electrolysis, 50-60 °С)

Receipt:

K 2 CO 3 + 2НI = 2 KI+ CO 2 + H 2 O

A discussion of the topic of why bleach is harmful should begin with a clarification of what, in fact, it is. Chlorine is a chemical element that is very abundant in nature. People have long discovered chlorine and in everyday life they most often use it for disinfection purposes. Unfortunately, the toxicity potential of chlorine is not limited to fighting mold and fungus, and in fact, the harmful properties of chlorine can indeed be associated with a serious danger to human health.

What is chlorine: general facts

Chlorine is a chemical used in industry and household cleaners. At room temperature, chlorine is a yellow-green gas with a pungent, irritating, bleach-like odor. Typically, chlorine is stored under pressure and refrigeration and shipped as an amber liquid. Chlorine itself is not very flammable, but in combination with other substances, it forms explosive compounds.

Use of chlorine

Chlorine has many uses. It is used to disinfect water and is part of the sanitation process for sewage and industrial waste. In the manufacture of paper and cloth, chlorine is used as a bleaching agent. It is also used in detergents, including household bleach, which is chlorine dissolved in water. Chlorine is used to make chlorides, chlorinated solvents, pesticides, polymers, synthetic rubbers, and coolants.

Why chlorine is dangerous for people

Due to its widespread use in industrial and commercial environments, exposure to chlorine can come from accidental spills or releases, or from a deliberate act. The most harmful exposure to chlorine is from inhaling chlorine gas. Problems can also arise from skin or eye contact with chlorine gas or from swallowing food or water with bleach.

Chlorine gas is heavier than air and initially remains in low-lying areas unless wind or other conditions favor air movement.

What is harmful chlorine: what happens to chlorine in the body

When chlorine enters the body through breathing, swallowing, or skin contact, it reacts with water to form acids. Acids contribute to corrosion and damage to cells in the body upon contact.

Chlorine Harm: Immediate Health Effects of Chlorine Exposure

Most of the harmful effects of chlorine are the result of inhalation. The health effects usually begin within seconds to minutes. After exposure to chlorine, the most common symptoms are:

• Respiratory tract irritation
• Wheezing
• Labored breathing
• sore throat
• Cough
• Chest tightness
• Eye irritation
• Skin irritation

The severity of health effects depends on the mode of exposure, dose and duration of exposure to chlorine. Inhaling large amounts of chlorine causes fluid to build up in the lungs, a condition known as pulmonary edema. The development of pulmonary edema may be delayed for several hours after exposure to chlorine. Contact with compressed liquid chlorine can cause frostbite to the skin and eyes.

What to do if you have been exposed to chlorine

If you have already encountered chlorine emissions, follow these steps:

How is chlorine poisoning treated?

To limit health effects from chlorine exposure, flush eyes and skin as quickly as possible with large volumes of water.

Modern medicine does not know of an antidote for chlorine poisoning, but the effects of chlorine are treatable and most people recover from chlorine poisoning. People who experience severe health effects (eg, severe eye and respiratory irritation, very bad cough, difficulty breathing, pulmonary edema) may need hospital treatment.

Lab tests to make treatment decisions if someone is exposed to chlorine

Laboratory testing for chlorine exposure will not be helpful in making treatment decisions. A person who is exposed to harmful amounts of chlorine will be noticed immediately due to bad breath and skin, eye, nose and/or throat irritation problems. Thus, the diagnosis and treatment of chlorine poisoning will primarily be based on the patient's medical history and the health effects of chlorine exposure.

Harm of bleach as a disinfectant

Chlorine is found in many household cleaners, it is used as a fumigant, and because it inhibits the growth of bacteria such as E. coli and Giardia, it is often added to water systems as a disinfectant. While disinfection of drinking water is a necessary measure to reduce disease, chlorine safety concerns are associated with some serious adverse health effects, including dementia in older patients.

Why can you get poisoned by chlorine in the pool?

Swimming pool water must be purified with some means to prevent contamination and bacterial growth. Chlorine is not the safest method, but probably the most common. Remember that chlorine is a poison. Dilute it just enough to be strong enough, but not strong enough to kill a person.

Some research confirms that long-term swimming in chlorinated pools can cause asthma symptoms in swimmers. This can affect athletes who were previously healthy, especially teenagers. In addition, there is a hypothesis that eye and skin irritation in swimmers is also associated with bleach.
By the way, scientists from the New York University College of Dentistry found that chlorinated water has a detrimental effect on tooth enamel.

Why chlorine is dangerous at home

Millions of accidents and injuries occur every year in residential areas, and many of them involve exposure to toxic chemicals, particularly in bleach. Its composition can release chlorine gas, which irritates the respiratory system when inhaled. If you've ever used bleach to clean an enclosed space, you've probably experienced a chlorine burn. Remember that chlorine is toxic enough to be considered a real chemical weapon and is classified as a breath arrest agent. Inhaling chlorine can cause breathing difficulties, chest pain, coughing, eye irritation, increased heart rate, rapid breathing, and even death. Smelling bleach or cleaner for a long time can be a very traumatic experience. By the way, chlorine poisoning has recurring symptoms.

How to protect yourself from exposure to chlorine

1. Try to reduce the risks of exposure to bleach in your home. If you have a pool, avoid products containing chlorine. There are alternative methods that can be used to disinfect water, including using silver ions, copper generators, and salt water.
2. To protect yourself in chlorinated pools, put on a mask to protect your eyes, and after swimming, leave the pool and breathe fresh air to get the gas out of your "system". A shower will quickly and thoroughly wash the chlorine off your skin.
3. Sunblock will not protect you from chlorine exposure. Choose public pools that are not cleaned with chlorine, but with more modern and safe disinfection methods. Many use a silver and copper ion generator.
4. Avoid household cleaners that contain chlorine. There are natural and organic alternatives. You can even make your own.
5. One of the most significant steps you can take to ensure you always drink purified water is to consider installing a water purification system for your home. This will help reduce toxins before the water even reaches the faucet.

Disclaimer: The information provided in this article about the dangers of bleach is intended to inform the reader only. It cannot be a substitute for the advice of a health professional.

DEFINITION

Chlorine- the seventeenth element of the Periodic table. Designation - Cl from the Latin "chlorum". Located in the third period, VIIA group. Refers to non-metals. The nuclear charge is 17.

The most important natural chlorine compound is sodium chloride (common salt) NaCl. The main mass of sodium chloride is found in the water of the seas and oceans. The waters of many lakes also contain significant amounts of NaCl. It is also found in solid form, forming thick layers of so-called rock salt in places in the earth's crust. Other chlorine compounds are also common in nature, for example, potassium chloride in the form of the minerals carnallite KCl × MgCl 2 × 6H 2 O and sylvite KCl.

Under normal conditions, chlorine is a yellow-green gas (Fig. 1), which is highly soluble in water. Upon cooling, crystalline hydrates are released from aqueous solutions, which are clarates of the approximate composition Cl 2 × 6H 2 O and Cl 2 × 8H 2 O.

Rice. 1. Chlorine in a liquid state. Appearance.

Atomic and molecular weight of chlorine

The relative atomic mass of an element is the ratio of the mass of an atom of a given element to 1/12 of the mass of a carbon atom. The relative atomic mass is dimensionless and is denoted by A r (the index “r” is the initial letter of the English word relative, which means “relative” in translation). The relative atomic mass of atomic chlorine is 35.457 amu.

The masses of molecules, just like the masses of atoms, are expressed in atomic mass units. The molecular weight of a substance is the mass of a molecule, expressed in atomic mass units. The relative molecular weight of a substance is the ratio of the mass of a molecule of a given substance to 1/12 of the mass of a carbon atom, the mass of which is 12 amu. It is known that the chlorine molecule is diatomic - Cl 2 . The relative molecular weight of a chlorine molecule will be equal to:

M r (Cl 2) = 35.457 × 2 ≈ 71.

Isotopes of chlorine

It is known that in nature chlorine can be in the form of two stable isotopes 35 Cl (75.78%) and 37 Cl (24.22%). Their mass numbers are 35 and 37, respectively. The nucleus of the atom of the chlorine isotope 35 Cl contains seventeen protons and eighteen neutrons, and the isotope 37 Cl contains the same number of protons and twenty neutrons.

There are artificial isotopes of chlorine with mass numbers from 35 to 43, among which the most stable is 36 Cl with a half-life of 301 thousand years.

Chlorine ions

On the outer energy level of the chlorine atom, there are seven electrons that are valence:

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

As a result of chemical interaction, chlorine can lose its valence electrons, i.e. be their donor, and turn into positively charged ions or accept electrons from another atom, i.e. be their acceptor, and turn into negatively charged ions:

Cl 0 -7e → Cl 7+;

Cl 0 -5e → Cl 5+;

Cl 0 -4e → Cl 4+;

Cl 0 -3e → Cl 3+;

Cl 0 -2e → Cl 2+;

Cl 0 -1e → Cl 1+;

Cl 0 +1e → Cl 1-.

Molecule and atom of chlorine

The chlorine molecule consists of two atoms - Cl 2 . Here are some properties that characterize the atom and molecule of chlorine:

Examples of problem solving

EXAMPLE 1

Chlorine, one might say, is already a constant companion of our daily life. Rarely in which house will there not be household products based on the disinfecting effect of this element. But at the same time, it is very dangerous for humans! Chlorine can enter the body through the mucous membrane of the respiratory system, digestive tract, and skin. You can poison them both at home and on vacation - in many pools, water parks, it is the main means of water purification. The effect of chlorine on the human body is sharply negative, it can cause serious dysfunction and even death. Therefore, everyone needs to be aware of the symptoms of poisoning, first aid methods.

Chlorine - what is this substance

Chlorine is a yellowish gaseous element. It has a sharp specific odor - In gaseous form, as well as in chemical forms, which imply its active state, it is dangerous, toxic to humans.

Chlorine is 2.5 times heavier than air, so in the event of a leak it will spread along ravines, the spaces of the first floors, and along the floor of the room. When inhaled, the victim may develop one of the forms of poisoning. We will talk about this further.

Symptoms of poisoning

Both prolonged inhalation of vapors and other exposure to the substance are very dangerous. Since it is active, the effect of chlorine on the human body manifests itself quickly. The toxic element affects the eyes, mucous membranes and skin to a greater extent.

Poisoning can be both acute and chronic. However, in any case, with untimely assistance, a fatal outcome threatens!

Symptoms of poisoning with chlorine vapor can be different - depending on the specifics of the case, the duration of exposure and other factors. For convenience, we have delimited the signs in the table.

This is the effect of chlorine on the human body. Let's talk about where you can get poisoned by its poisonous fumes and how to provide first aid in this case.

Poisoning at work

Chlorine gas is used in many industries. You may well get a chronic form of poisoning if you work in the following industries:

• Chemical industry.
• Textile factory.
• pharmaceutical industry.

Vacation poisoning

Although many are aware of the effect of chlorine on the human body (of course, in large volumes), not all saunas, swimming pools, and entertainment water complexes strictly monitor the use of such a budget disinfectant. But its dosage is very easy to accidentally exceed. Hence the chlorine poisoning of visitors, which happens quite often in our time.

How to notice that during your visit the dose of the element in the pool water is exceeded? Very simple - you will feel a strong specific smell of the substance.

What happens if you often visit the pool, where they violate the instructions for using Dez-chlor? Visitors should be wary of constant dry skin, brittle nails and hair. In addition, swimming in highly chlorinated water, you risk getting mild element poisoning. It manifests itself with the following symptoms:

• cough;
• vomit;
• nausea;
• in rare cases, inflammation of the lungs occurs.

Poisoning at home

Poisoning can also threaten you at home if you have violated the instructions for using Dez-Chlor. A chronic form of poisoning is also common. It develops if the housewife often uses the following means to clean up:

• Bleachers.
• Preparations designed to combat mold.
• Tablets, washing liquids, which contain this element.
• Powders, solutions for general disinfection of the premises.

Effects of chlorine on the body

The constant impact of even small doses of chlorine (the state of aggregation can be any) on the human body threatens people with the following:

• Pharyngitis.
• Laryngitis.
• Bronchitis (in acute or chronic form).
• Various diseases of the skin.
• Sinusitis.
• Pneumosclerosis.
• Tracheitis.
• Visual impairment.

If you have noticed one of the ailments listed above, provided that you have been constantly or once (cases of visiting the pool also applies here) were exposed to chlorine vapor, then this is a reason to contact a specialist as soon as possible! The doctor will prescribe a comprehensive diagnosis to study the nature of the disease. After studying its results, then he will prescribe treatment.

First aid for poisoning

Chlorine is a gas that is very dangerous to inhale, especially in large volumes! With an average, severe form of poisoning, the victim should immediately receive first aid:

1. Whatever the state of the person, do not panic. You should first of all pull yourself together, and then calm him down.
2. Remove the victim to fresh air or to a ventilated area free of chlorine fumes.
3. Call an ambulance as soon as possible.
4. Make sure that the person is warm and comfortable - cover him with a blanket, blanket or sheet.
5. Make sure that he breathes easily and freely - remove tight clothing, jewelry from the neck.

Medical care for poisoning

Before the arrival of the ambulance team, you can help the victim yourself, using a number of household and medical preparations:

• Prepare a 2% baking soda solution. Rinse the victim's eyes, nose, and mouth with this liquid.
• Put vaseline or olive oil in his eyes.
• If a person complains of pain, pain in the eyes, then in this case, a 0.5% dicaine solution would be best. 2-3 drops for each eye.
• For prevention, an eye ointment is also applied - synthomycin (0.5%), sulfanilic (10%).
• Albucid (30%), zinc sulfate solution (0.1%) can be used as a substitute for eye ointment. These drugs are instilled into the victim twice a day.
• Intramuscular, intravenous injection. "Prednisolone" - 60 mg (intravenously or intramuscularly), "Hydrocortisone" - 125 mg (intramuscularly).

Prevention

Knowing how dangerous chlorine is, what substance has an effect on the human body, it is best to take care of reducing or eliminating its negative impact on your body in advance. This can be achieved in the following ways:

• Compliance with sanitary standards in the workplace.
• Regular medical examinations.
• The use of protective equipment when working with chlorine-containing drugs at home or at work - the same respirator, tight protective rubber gloves.
• Compliance with safety regulations when working with the substance in an industrial environment.

Working with chlorine always requires caution, both on an industrial scale and in households. You know how to diagnose yourself for signs of substance poisoning. Assistance to the victim must be provided immediately!