ЦИАНИД НАТРИЯ

Описание

Sodium cyanide, NaCN, is a cyanide salt that is a white, deliquescent, crystalline powder and is soluble in water. The specific gravity is 1.6, which is heavier than water. Sodium cyanide is toxic by inhalation and ingestion, with a TLV of 4.7 ppm and 5 mg/m3 of air. The target organs are the cardiovascular system, central nervous system, kidneys, liver, and skin. Reactions with acids can release flammable and toxic hydrogen cyanide gas. Cyanides are incompatible with all acids. The four-digit UN identification number is 1689.
The NFPA 704 designation is health 3, flammability 0, and reactivity 0. The primary uses are in gold and silver extraction from ores, electroplating, fumigation, and insecticides.

Химические свойства

Sodium cyanide is found as white granules, flakes or lumps. Sodium cyanide is shipped as pellets or briquettes. Odorless when dry. It absorbs water from air (is hygroscopic or deliquescent). Hydrogen cyanide gas released by sodium cyanide has a distinctive mild, bitter almond odor, but a large proportion of people cannot detect it; the odor does not provide adequate warning of hazardous concentrations.

Физические свойства

Physical Properties White cubic crystals; hygroscopic; density 1.6 g/cm³; melts at 563°C; very soluble in water; aqueous solution strongly alkaline and decomposes rapidly.

Использование

Sodium cyanide is used for electroplating metals such as zinc, copper, cadmium, silver, and gold, and their alloys; for extracting gold and silver from ores; and as a fumigant and a chelating agent. It occurs in many varieties of maniocs (cassava), especially in bitter manioc.

Определение

sodium cyanide: A white orcolourless crystalline solid, NaCN,deliquescent, soluble in water and inliquid ammonia, and slightly solublein ethanol; cubic; m.p. 564°C; b.p.1496°C. Sodium cyanide is now madeby absorbing hydrogen cyanide insodium hydroxide or sodium carbonatesolution. The compound is extremelypoisonous because it reacts with the iron in haemoglobin in theblood, so preventing oxygen reachingthe tissues of the body. It is used inthe extraction of precious metals andin electroplating industries. Aqueoussolutions are alkaline due to salt hydrolysis.

Подготовка

Sodium cyanide can be prepared by several methods (See Potassium Cyanide).
It is prepared by passing hydrogen cyanide through a 50% aqueous solution of sodium hydroxide followed by evaporation of the solution in vacuum: NaOH + HCN → NaCN + H₂O
Another method is to reduce sodamide with carbon at red heat: NaNH₂ + C → NaCN + H₂↑
Also, sodium cyanide can be made by heating a mixture of sodium carbonate and carbon with ammonia at high temperatures: Na₂CO₃ + 4C + 2NH₃ → 2NaCN + 3CO↑ + 3H₂↑.

Методы производства

Sodium cyanide was first prepared in 1834 by heating Prussian Blue, a mixture of cyanogen compounds of iron, and sodium carbonate and extracting sodium cyanide from the cooled mixture using alcohol. Sodium cyanide remained a laboratory curiosity until 1887, when a process was patented for the extraction of gold and silver ores by means of a dilute solution of cyanide.

Реакции

Sodium cyanide, NaCN, white solid, soluble, very poisonous, formed (1) by reaction of sodamide and carbon at high temperature, (2) by reaction of calcium cyanamide and sodium chloride at high temperature, reacts in dilute solution in air with gold or silver to form soluble sodium gold or silver cyanide, and used for this purpose in the cyanide process for recovery of gold. The percentage of available cyanide is greater than in potassium cyanide previously used. Used as a source of cyanide, and for hydrocyanic acid.

Общее описание

A clear colorless aqueous solution.

Реакции воздуха и воды

Slowly evolves flammable and poisonous hydrogen cyanide gas.

Профиль реактивности

Sodium cyanide is weakly basic. Reacts with acids of all kinds to generate quantities of very poisonous hydrogen cyanide gas. Incompatible with strong oxidizing agents, especially if solution dries out. Gives insoluble products with silver(I), mercury(I) and lead(II) ions that may decompose violently under certain conditions.

Опасность

Toxic by ingestion and inhalation.

Угроза здоровью

Sodium cyanide is a white crystalline solid that is odorless when dry, but emits a slight odor of hydrogen cyanide in damp air. It is slightly soluble in ethanol and formamide. It is very poisonous. It explodes if melted with nitrite or chlorate at about 450°F. It produces a violent reaction with magnesium, nitrites, nitrates, and nitric acid. On contact with acid, acid fumes, water, or steam, it produces toxic and flammable vapors. Synonyms for sodium cyanide are hydrocyanic acid, sodium salt, and cyanide of sodium.

Воспламеняемость и взрывоопасность

Sodium cyanide and potassium cyanide are noncombustible solids. Reaction with acids liberates flammable HCN.

Промышленное использование

sodium cyanide and other water-soluble cyanides are used as modifying reagents for selective flotation of ores containing galena, sphalerite and gangue minerals.

Возможный контакт

Sodium cyanide is used as a solid or in solution to extract metal ores, in electroplating and metal cleaning baths; in metal hardening; in treatment of rabbit and rat burrows and holes and termite nests; in insecticides

хранилище

In particular, work with cyanides should be conducted in a fume hood to prevent exposure by inhalation, and splash goggles and impermeable gloves should be worn at all times to prevent eye and skin contact. Cyanide salts should be stored in a cool, dry location, separated from acids.

Перевозки

UN1689 Sodium cyanide, Hazard Class: 6.1; Labels: 6.1-Poisonous materials.

Несовместимости

Sodium cyanide decomposes on contact with acids, acid salts, water, moisture, alcohols, and carbon dioxide, releasing highly toxic and flammable hydrogen cyanide gas. Aqueous solution is a strong base; it reacts violently with acid and is corrosive. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides. Absorbs moisture from the air forming a corrosive syrup. Corrosive to active metals, such as aluminum, copper, and zinc. Under acid conditions, sarin hydrolyzes to form hydrofluoric acid.

Утилизация отходов

Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform to EPA regulations governing storage, transportation, treatment, and waste disposal. In accordance with 40CFR165, follow recommendations for the disposal of pesticides and pesticide containers. Must be disposed properly by following package label directions or by contacting your local or federal environmental control agency, or by contacting your regional EPA office. Add strong alkaline hypochlorite and react for 24 hours. Then flush to sewer with large volumes of water.