Sodium chloride is an ionic compound with the chemical formula NaCl. It is colorless cubic crystal or fine crystalline powder, and tastes salty.
The appearance is white crystal, and its source is mainly seawater, which is the main component of table salt. Soluble in water, glycerin, slightly soluble in ethanol (alcohol), liquid ammonia, insoluble in concentrated hydrochloric acid. Impure sodium chloride is deliquescent in air.
The stability is relatively good, and its aqueous solution is neutral. Industrially, the method of electrolytically saturated sodium chloride solution is generally used to produce hydrogen, chlorine and caustic soda (sodium hydroxide) and other chemical products (commonly called Chlor-alkali industry).
It can be used in ore smelting (electrolytic melting of sodium chloride crystals to produce active metal sodium), medically used to configure physiological saline, and daily life can be used for condiments.
English name: sodium chloride
English alias: sodium hydrochloride; Sodium chloride
CAS number: 7647-14-5
Molecular formula: NaCl
Molecular weight: 58.44280
Exact mass: 57.95860
Customs code: 2501002000
Danger category code: R36; R22
Safety instructions: S24 / 25-S26
Dangerous goods sign: Xi
Physical properties of Sodium chloride
Appearance and properties: colorless crystal or white powder
Density: 2.165g / cm³ (25 ° C)
Water solubility: 360 g / L (25 ºC)
Stability: Stable under normal shipping and handling conditions.
Storage conditions: low temperature, ventilated and dry in warehouse
Vapor pressure: 1 mm Hg (865 ° C)
Melting point: 801 ° C
Boiling point: 1465 ℃
Sodium chloride is a white odorless crystalline powder. Mp 801 deg.] C, a boiling point of 1465 deg.] C, slightly soluble in ethanol, propanol, butane, butane, and after the plasma becomes miscible, soluble in water, the water solubility of 35.9 g (room temperature).
NaCl is dispersed in alcohol to form colloids. Its solubility in water is reduced by the presence of hydrogen chloride, and it is almost insoluble in concentrated hydrochloric acid.
Chemical properties of Sodium Chloride
The crystals of sodium chloride form stereo symmetry. In its crystal structure, the larger chloride ions form the densest packing in the cube, and the smaller sodium ions fill the octahedral gap between the chloride ions. Each ion is surrounded by six other ions. This structure is also found in many other compounds, called sodium chloride type structure or stone salt structure.
1. Preparation of sodium metal by electrolytic melting of sodium chloride
2NaCl(molten) = 2Na + Cl2
2. Electrolytic saltwater
2NaCl + 2H2O = H2 + Cl2 + 2NaOH
3. React with silver nitrate
NaCl + AgNO3 = NaNO3 + AgCl
Cl– + Ag+ = AgCl
(Which is the essence CI – property)
4. Reaction with concentrated sulfuric acid (laboratory hydrogen chloride)
( Concentrated behalf concentrated, Excess Representative excess)
A: chloride was added dropwise to a solution of nitric acid had acidified solution of silver nitrate, a white precipitate (precipitated silver chloride) is generated, proved CI– .
B: Dip a small amount of solution with platinum wire and put it on an alcohol lamp to burn. The flame is yellow and it can be proven that it contains Na+.
C: In order to eliminate interference, the original test solution can be added with saturated barium hydroxide until it is obviously alkaline. At this time, most cations and anions such as PO43− and AsO43− will be precipitated.
Ba2+ introduced into the test solution should be removed by ammonium carbonate, and finally ammonium salt should be removed by burning. After the residue was leached with water, the solution was acidified with HAc, and the uranyl zinc acetate reagent was added according to the number of drops of 1: 8, and the tube wall was rubbed with a glass rod. If lemon-yellow crystals were formed, Na+ was present.
Preparation of Sodium Chloride
Introduced into salt fields by seawater (average of 2.4% sodium chloride) and dried in the sun, Concentrated to crystallize to obtain a crude product. The seawater can also be heated by steam, filtered by a sand filter, and concentrated by ion-exchange membrane electrodialysis to obtain brine (containing sodium chloride 160-180g / L).
The halo gypsum is precipitated by evaporation, and the obtained chlorine is centrifuged. More than 95% sodium (2% moisture) can be dried to obtain common salt. Rock salt and salt lake brine can also be used as raw materials and dried in the sun to obtain raw salt.
When underground brine and well salt are used as raw materials, they are concentrated by three- or four-effect evaporation, crystals are precipitated, and centrifuged to obtain.
The crude salt is dissolved in water to remove insoluble impurities, and refined preparations such as sodium hydroxide and sodium carbonate are added to make soluble impurities such as SO42-, Ca2+ and Mg2+ become precipitates, filtered to remove, and finally purified with The pH was adjusted to 7 with hydrochloric acid, and the solution was concentrated to obtain pure sodium chloride crystals.
The preparation method in the laboratory is to mix an equal amount of hydrochloric acid with sodium hydroxide to form a sodium chloride solution. The solution was then distilled to obtain sodium chloride crystals. The main reaction:
In addition, sodium chloride will also produce sodium chloride when ignited in the environment of chlorine gas. Its chemical equation is:
what is Sodium Chloride used for
1. When electrolytic sodium chloride solution is electrolyzed, hydrogen and chlorine gas will be generated. Chlorine gas has a wide range of applications in the chemical industry and can be used to synthesize polyvinyl chloride, pesticides, hydrochloric acid, etc.
2. Preparation of sodium metal by the Dangs method: Preparation of sodium metal by electrolytically melting a mixture of sodium chloride and calcium chloride. Calcium chloride is used as a flux to lower the melting point of sodium chloride below 700 ° C. Calcium is less reductive than sodium and does not introduce impurities.
3. Sodium chloride is necessary for many biological reactions. For example, various solution formulas in molecular biology experiments contain sodium chloride, and most of the bacterial culture medium contains sodium chloride. It is also the raw material in the production of soda ash by the ammonia-alkali method.
4. Inorganic and organic industries are used as raw materials for the production of caustic soda, chlorate, hypochlorite, bleaching powder, refrigerants for refrigeration systems, raw materials for organic synthesis and salting-out agents. The steel industry is used as a heat treatment agent. A high-temperature heat source is used to form a salt bath with potassium chloride, barium chloride, etc., which can be used as a heating medium to maintain the temperature between 820-960 ° C. In addition, it is also used in glass, dyes, metallurgy and other industries.
5. Analytical reagents are used as fluorine and silicate trace analysis reagents.
6. Soda ash production by Hou’s alkali method: the second step: the ammonium bicarbonate solution prepared in the first step is mixed with the sodium chloride solution to obtain sodium bicarbonate and ammonium chloride at 10°C.
The food industry and fisheries are used for salting, as well as raw materials for seasonings and refined table salt.
Adding salt to cooking dishes can remove some odors of raw materials and increase the taste, which is the effect of salt freshness. “Slightly tasteless, salty and tasteless” means that the proper amount of salt can be used to exert its unique functions.
Sodium chloride is very important for life on Earth. Most biological tissues contain multiple salts. The concentration of sodium in the blood is directly related to the regulation of the safe level of body fluids. The conduction of nerve impulses caused by signal conversion is also regulated by sodium ions.
Water containing 0.9% sodium chloride is called saline because it has the same osmotic pressure as plasma. Normal saline is the main body fluid substitute. It is widely used in the treatment and prevention of dehydration, and it is also used in the treatment of intravenous injection and the prevention of hypovolemic shock.
Unlike other primates, humans secrete large amounts of sodium chloride through sweating.
Sodium chloride is indispensable for humans. The total amount of sodium ions contained in adults is about 60g, 80% of which is in extracellular fluid, that is, in plasma and intercellular fluid. Chloride is also mainly present in extracellular fluid. The physiological functions of sodium and chloride ions are:
(1) maintaining the osmotic pressure of the extracellular fluid.
(2) participate in the regulation of acid-base balance in the body.
(3) Chloride is involved in the production of gastric acid in the body. In addition, sodium chloride also plays a role in maintaining the normal excitability of nerves and muscles.
Its aqueous solution can be used for seed selection. The NaCl solution is configured according to the needs of the species, and its density is greater than that of water. Seeds are put into NaCl solution, floating full and sinking full.
According to new findings released by the Singapore Science and Technology Research Institute, sodium chloride can significantly increase the capacity of hard drives. Specifically, the existing conventional hard disk uses a randomly allocated magnetic disk storage technology, which can only achieve a data density of 0.5TB per square inch.
The new technology benefits from the help of sodium chloride. With the new high-resolution lithography factor technology, the data density will be more orderly, reaching 3.3TB per square inch without the need for complicated equipment upgrades. Using 1TB hard disk with this technology can reach 6TB capacity without adding discs.
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