Potassium Cyanide - KCN

What is Potassium Cyanide?

Potassium Cyanide is a chemical compound which arises due to the reaction between hydrogen cyanide (HCN) and potassium hydroxide (KOH). It is also called Cyanide of potassium or Cyanopotassium. The chemical formula of Potassium Cyanide is KCN.

It is a crystalline salt which has no colour and is highly toxic and soluble in water. It has a smell of bitter almonds and tastes like acrid with a burning sensation. It is a cyanide salt which contains an equal number of cyanide anions and potassium cations. It is a cyanide salt, potassium salt, and a one-carbon compound.

Properties of Potassium Cyanide – KCN

Potassium Cyanide KCN
Molecular Weight of Potassium Cyanide 65.12 g/mol
Density of of Potassium Cyanide 1.52 g/cm3
Melting Point of Potassium Cyanide 634.5 °C
Boiling point of Potassium Cyanide 1,625 °C

Structure of Potassium Cyanide (KCN)

Structure of Potassium Cyanide

Uses of Potassium Cyanide (KCN)

  • Potassium Cyanide is used in the extraction of silver and gold from ores.
  • It is used in the electroplating process.
  • Used as a reagent in analytical chemistry.
  • It is widely used in the preparation of carboxylic acids and nitriles.
  • It is used in the wet plate collodion process as a photographic fixer.
  • It is used in gold mining.
  • Used in warehouses.

Preparation of Potassium Cyanide

It is obtained by the treatment of hydrogen cyanide (HCN) with a solution of potassium hydroxide (KOH). Further, it is evaporated in a vacuum:


Approximately 50,000 tons of potassium cyanide (KCN) is produced annually.

Historically Production of KCN

Potassium cyanide (KCN) was an important source of alkali metal cyanides before the invention of the Castner process. It was produced by the decomposition of potassium ferrocyanide. The reaction is as follows:

K4[Fe(CN)6] → 4 KCN + FeC2 + N2

Effects on Health

It is a highly poisonous compound which acts as an inhibitor for many metabolic processes. It is toxic by skin absorption through and opens wounds. When it is heated to decomposition it produces toxic fumes. It is widely used for silver extraction and as an insecticide.

Learn more about the physical and chemical properties of Potassium Cyanide (KCN) from the experts at BYJU’S.

Leave a Comment

Your email address will not be published. Required fields are marked *