chloride

[l ǜ huà wù]

Salt compounds

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Chloride in inorganic chemistry In the field, it refers to the belt negative electricity Of Chloride ion And other elements positive electricity Of cation The salt compound formed by combination, in a broad sense, chloride can also be said to be chlorine and another element or Group Constituent chemical compound 。

Chinese name: chloride

Foreign name: chloride
Preparation method: Metal in chlorine Medium combustion, or reaction with hydrochloric acid

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▪ Phosphorus trichloride
six Chlorine and human body

Basic properties

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Chlorides generally have high melting and boiling points (ammonium chloride will "sublimate"). See Table 1 for the melting and boiling points and related substances of some common chlorides. When some metals (such as gold) are dissolved in aqua regia, chloroauric acid (such as chloroauric acid) will be produced, nitric oxide And water. The most common chloride is sodium chloride, which is the main component of table salt, and the chemical formula is NaCl. Sodium chloride is widely used, and its electrolysis produces chlorine, hydrogen and sodium hydroxide , chlorine and hydrogen are used to prepare hydrochloric acid; Sodium chloride and calcium chloride are fused and electrolyzed to produce sodium metal; Sodium chloride is also the raw material for soda ash production by ammonia soda.

Table 1 Melting and boiling points and relevant properties of some common chlorides
chloride	Melting point/℃	Boiling point/℃	Relevant nature
sodium chloride	eight hundred and one	one thousand four hundred and thirteen	Easily soluble in water, very slightly soluble in ethanol, almost insoluble in concentrated hydrochloric acid.
potassium chloride	seven hundred and seventy	1500 (some will be sublimated)	Easily soluble in water, ether, glycerin and alkali, slightly soluble in ethanol, but insoluble in absolute ethanol.
lithium chloride	six hundred and five	one thousand three hundred and fifty	Easily soluble in water, ethanol, acetone, pyridine and other organic solvents.
Ferric chloride	two hundred and eighty-two	three hundred and fifteen	Brown black crystal, soluble in water and strong water absorption, insoluble in glycerin.
Ferrous chloride	670-674		Anhydrous ferrous chloride is a yellow green hygroscopic crystal, which is soluble in water, ethanol and methanol.
calcium chloride	seven hundred and seventy-two	>1600	It is white, hard fragments or particles at room temperature, easily soluble in water, and gives off heat when dissolved.
Cupric chloride	six hundred and twenty	nine hundred and ninety-three	Green to blue powder or rhombic bipyramid crystal. Deliquescence in wet air.

physical property

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Common chlorides (4 sheets)

Most chlorides containing water crystals are colorless crystals (but copper chloride is blue crystal, Ferrous chloride Is green crystal, and ferric chloride is brown crystal); Soluble in water (silver chloride and Mercurous chloride Insoluble, lead chloride is slightly soluble in cold water) and forms ions, which is also a chloride solution electric conduction Reason for. Chlorides generally have high melting and boiling points (ammonium chloride will "sublimate").

Inspection method

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because silver nitrate encounter Chloride ion It will produce white silver chloride precipitates that are insoluble in nitric acid, so it can be used to test the existence of chloride ions.

Ionic equation ：Ag + +Cl - = AgCl↓

Preparation method

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Metal burns in chlorine

The metal chloride can be obtained by burning the metal in chlorine, for example, the metal sodium burns in chlorine to form sodium chloride, which belongs to Redox reaction 。

Reaction of active metals with hydrochloric acid

Some active metals react with hydrochloric acid solution to form chlorides of the metal, which belongs to oxidation-reduction reaction. However, it should be noted that not all metals can react with hydrochloric acid to form salts, only when Metal mobility Only the metal ranking before hydrogen in the order list can react with hydrochloric acid to form chlorides and hydrogen, such as magnesium, aluminum, calcium, potassium, iron, zinc, etc., while gold, platinum The less active metals after hydrogen in the metal activity sequence table cannot react with hydrochloric acid to form chlorides. Potassium, calcium, sodium and other metals will react directly with hydrochloric acid.

In addition, chlorides can also be obtained by reacting oxides, carbonates, hydroxides, etc. with hydrochloric acid.

Common chlorides

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Hydrogen chloride

1. Basic nature:

Molecular structure of hydrogen chloride

Hydrogen chloride (HCl), a molecule of hydrogen chloride is composed of a chlorine atom and a hydrogen atom, which is colorless and has thrill Odorous gas. Its aqueous solution is commonly known as hydrochloric acid , scientific name is hydrochloric acid. relative molecular mass 36.46. Hydrogen chloride is very soluble in water. At 0 ℃, one volume of water can dissolve about 500 volumes of hydrogen chloride.

Hydrogen chloride Mainly used for manufacturing dyestuff , spices, medicines, various chlorides and Corrosion inhibitor 。

2. Hydrogen chloride production in laboratory:

Generally, solid sodium chloride reacts with concentrated sulfuric acid without heating or slightly heating to generate Sodium bisulfate And hydrogen chloride.^[1]

Laboratory hydrogen chloride production unit

NaCl+H two SO four = NaHSO four +HCl↑

Then, under the condition of 500 ℃ to 600 ℃, continue to react to generate hydrogen chloride and sodium sulphate 。

NaHSO four +NaCl = Na two SO four +HCl↑

Overall Chemical equation It can be expressed as follows:

2NaCl+H two SO four = Na two SO four +2HCl ↑ (Note: HCl can only be added ↑ in the environment of heating and water shortage)

2. Industrial production of hydrogen chloride - chlor alkali industry:

2NaCl+2H two O=Energized=2NaOH+H two ↑+Cl two ↑

H two +Cl two =Ignition=2HCl

sodium chloride

Molecular structure of sodium chloride

Sodium chloride, chemical formula NaCl, colorless cubic crystal or fine crystalline powder, salty. The appearance is white crystal, and its source is mainly sea water, which is the main component of table salt. Soluble in water , glycerin, slightly soluble in ethanol (alcohol) liquid ammonia ； Insoluble Concentrated hydrochloric acid 。 The impure sodium chloride is deliquescent in the air. It has good stability, its aqueous solution is neutral, and electrolytic saturation is generally used in industry Sodium chloride solution It can be used to produce hydrogen, chlorine, caustic soda (sodium hydroxide) and other chemical products (generally referred to as chlor alkali industry), as well as ore smelting (electrolytic melting of sodium chloride crystals to produce active metal sodium), medical use to prepare physiological saline, and life can be used for flavoring.

Silver chloride

The appearance is white powder, unstable, easy to see the light decomposes into purple and gradually turns black. Water at 25 ℃ solubility 1.93mg/L, hydrochloric acid It can reduce its solubility in water and can dissolve in ammonia 、 Sodium cyanide 、 Sodium thiosulfate 、 Mercuric nitrate Solution. Insoluble ethanol and Dilute hydrochloric acid 。

Silver chloride is insoluble in water and dilute nitric acid. Therefore, it is often used in the laboratory to determine the silver content of silver chloride samples.

Still in AgCl suspension Silver ion Therefore, Zn can react with silver ion to displace silver, so AgCl suspension can react with Zn:

2AgCl+Zn = ZnCl two +2Ag

Silver sulfide The solubility of silver chloride is smaller than that of silver chloride. According to the principle of precipitation conversion, silver chloride can react with sulfur ions to generate silver sulfide:

2AgCl+Na two S = Ag two S+2NaCl

Silver chloride is used on very old and not very sensitive photographic film, offset plate and gummed paper. But generally, the film used is chemically similar, but more sensitive to light Silver bromide AgBr。

Phosphorus trichloride

Phosphorus trichloride The molecular formula of is PCl three , is a colorless transparent liquid, boiling point 76 ℃, hydrolysis reaction occurs when encountering ethanol and water:

3PCl three +3H two O = H three PO three +3HCl；

Phosphorus trichloride can form hydrochloric acid mist in the air. It is irritant and corrosive to skin and mucous membrane. Inhaling a large amount of steam in a short time can cause irritation symptoms of upper respiratory tract, pharyngitis bronchitis , serious cases may occur Laryngeal edema Suffocation, pneumonia or pulmonary edema. Skin and eye contact may cause irritation or burns. Severe eye burns can cause blindness. Chronic effect: long-term low concentration exposure may cause eye and respiratory tract irritation symptoms. It can cause phosphorus toxicity oral disease.

Chlorine and human body

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Some chemical elements in human body

Chlorine element It widely exists in the human body in the form of sodium chloride. The average adult body contains about 75-80g sodium chloride , mainly in the form of chloride ions, widely exists in tissues and body fluids, which are Extracellular fluid Most anion 。 It is related to Bicarbonate The content of is close. It can regulate water, osmotic pressure, acid and alkali in human body balance And so on. Chlorine ions are often absorbed and metabolized with sodium ions in the body, and the changes are often consistent. In addition, there are chlorides in human bones and stomach acid. The appropriate daily intake of sodium chloride for adults is 2-5g. Lack of chlorine in human body will lead to diarrhea, water shortage and other symptoms. baby If chlorine deficiency is caused by genetic factors, it will lead to Growth disorders 。 Some experts believe that too much sodium chloride intake will lead to hypertension.

Serum chloride (Cl) Normal value:

Calculated by chloride: 98~106mmol/L (98~106mEq/L).

Calculated by chlorine: 100~106mmol/L (55~376mg/dl).

Clinical significance of serum chloride (Cl):

(1) Increase:

① Decreased discharge: acute and chronic renal function failure 、 Renal tubule Sexual acidosis Obstructive nephropathy Etc.

② Excessive intake: high salt diet, input normal saline Too much, especially in Chronic renal insufficiency When.

③ Respiratory alkalosis 。

④ Hyperosmotic dehydration (water loss>sodium loss).

⑤ Bismuth bromide poisoning.

(2) Lower:

① Severe vomiting High intestinal obstruction , chronic pyloric obstruction, etc.

② Gastric juice, pancreatic juice bile Large loss, etc.

③ Chronic adrenocortical hypofunction 。

④ Serious diabetes Excessive urination causes acidosis.

⑤ Excessive sweating and failure to supplement sodium chloride in time.

⑥ Cardiac insufficiency And nephritis without salt or Low salt diet After massive diuresis.

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