Sodium cyanide

Sodium cyanide is an inorganic compound with the formula NaCN. It is a white, water-soluble solid. Cyanide has a high affinity for metals, which leads to the high toxicity of this salt. Its main application, in gold mining, also exploits its high reactivity toward metals. It is a strong base. When treated with acid, it forms the toxic gas hydrogen cyanide:

NaCN + H2SO4 → HCN + NaHSO4

Production and chemical properties

Sodium cyanide is produced by treating hydrogen cyanide with sodium hydroxide:

HCN + NaOH → NaCN + H2O

This reaction is a classic example of an acid-base neutralization reaction, where the acid HCN is neutralized by the base NaOH to form water and the salt sodium cyanide.

Sodium cyanide reacts rapidly with strong acids to release hydrogen cyanide. This dangerous process represents a significant risk associated with cyanide salts. It is detoxified in modern waste treatment processes by converting it into sodium ferrocyanide, which is less toxic.

Applications

Sodium cyanide is used mainly in gold mining but also has other uses such as electroplating and in the production of plastics.

Gold mining

The high affinity of cyanide for metals such as gold and silver makes it suitable for use in extracting these metals from ores. Sodium cyanide is an important reagent in gold mining.

Electroplating

Sodium cyanide is used in some electroplating processes. The cyanide allows the metal ions to react with the metal being plated without causing unwanted chemical reactions.

Other uses

Sodium cyanide is used in the production of plastics and other chemical products.

Toxicity

Sodium cyanide, like other cyanide salts, is among the most rapidly acting of all known poisons. Sodium cyanide is a potent inhibitor of respiration, acting on mitochondrial cytochrome oxidase and hence blocking electron transport. This results in decreased oxidative metabolism and oxygen utilization. Lactic acidosis then occurs as a consequence of anaerobic metabolism.

See also

• Hydrogen cyanide
• Cyanide poisoning
• Gold mining
• Electroplating

Sodium cyanide Resources
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