Potassium Cyanide

Potassium Cyanide - A Form of Cyanide

A compound named potassium cyanide is a colorless crystalline salt, similar to sugar particles in its appearance. Its general formula is KCN and IUPAC's name is Potassium Cyanide. Potassium Cyanide is a very poisonous inorganic salt. Potassium Cyanide is a highly toxic substance in nature and exposure to this element can be very much lethal for humans. Apart from all these circumstances, it is considered to be highly soluble in water. Mostly it is used in the gold mining industries for the extraction of gold and silver ores. It is also used in various other industries for electroplating, fumigation, chemical gilding, and buffing.  

Structure of Potassium Cyanide

  • Chemical Formula is KCN.

  • The molecular formula is KCN.

  • The molar mass of potassium cyanide is 65.12 g/mol.

Potassium cyanide is a compound formed of potassium( K+ cation ) and Cyanide (CN- anion). In which potassium is positively charged and cyanide is negatively charged ions. Carbon has a triple bond with the nitrogen ion. It is similar to the structure of NaCl crystalline solid.                

Properties of Potassium Cyanide

  • Potassium Cyanide is a white crystalline colorless solid.

  • Its density is 1.52 g/ml.

  • Its melting point is 634.5’c

  • Potassium cyanide is highly soluble in water.

  • It decomposes slowly in the air and rapidly after heating.

  • Potassium Cyanide, when reacted with hydrogen peroxide, forms a less harmful cyanide derivative.

  • KCN+ H₂O₂ -> KOCN+ H₂O

  • It is a toxic substance. It tastes bitter and it exhibits burning sensations.

Preparation of Potassium Cyanide

Potassium Cyanide can be prepared by various methods in industries as per their use. The most commonly used methods are:

  • When hydrogen cyanide is reacted with an aqueous solution of potassium hydroxide:-

HCN + KOH -> KCN + H₂O 

  • When Formamide is reacted with KOH:-

HCONH₂ + KOH -> KCN + 2H₂O

Uses of Potassium Cyanide

  • Potassium Cyanide and Sodium Cyanide are widely used for the production of nitriles and carboxylic acids.

  • Potassium Cyanide was produced for the decomposition of potassium ferrocyanide. It was produced before the invention of the Castner process.

  • In the colloidal process, KCN is used as a photographic fixer.

  • It is used in the gold mining procedure, where KCN forms water-soluble Potassium gold cyanide and Potassium Hydroxide in the presence of oxygen.

4Au+ 8KCN +O₂ +2 H₂O -> 4K[Au(CN)₂]+ 4KOH

  • KCN is used in mining industries of gold and other metals.

  • Potassium cyanide is used for the preparation of plastic and another organic synthesis.

  • It is used for electroplating and fumigation.

  • Potassium Cyanide is also used in warehouses.

  • It is also used as an insecticide by farmers.


Potassium cyanide is a highly toxic inorganic substance with the general formula KCN. It is generally prepared by the reaction of hydrogen cyanide (HCN) and potassium hydroxide (KOH). This is made up of a solid base (KOH) and a weak acid (HCN).  This is used for the extraction of gold, silver, and other metals. It is one of the forms of cyanide prepared for the decomposition of potassium ferrocyanide before the invention of the Castner process.

Potassium Cyanide is harmful to health. If someone inhales this element then they may face severe health problems which can even lead to death. A person may also suffer from headaches, vomiting, dizziness, and seizures which can be harmful to human health.

Potassium cyanide is a salt prepared with the help of hydrogen cyanide or a reagent formamide.

FAQ (Frequently Asked Questions)

1. What are the Harmful Effects of Potassium Cyanide?

Potassium cyanide is a harmful toxic substance and is very much similar to the crystalline solid of NaCl in appearance. 

  • It's toxic in many cases and high exposure to Potassium Cyanide can lead to headaches, nausea, dizziness, anxiety, and heart racing.

  • It can also lead to death in severe cases.

  • In some cases, if a person is suffering from any kind of chronic symptoms then eventually they will suffer from headache, nausea, vomiting or bright red flush if they come in contact with Potassium Cyanide

  • On the other hand, if a person is suffering from any kind of acute symptoms then he/she may face difficulty in breathing or either they may suffer from seizure or cardiac arrest.

  • According to sources of chemistry, it's said that even a single spoon of this toxic element can kill approximately 43% of the total population.

2.How can we Prepare Potassium Cyanide?

Potassium Cyanide can be prepared by various methods in the industries. Potassium cyanide was prepared for the decomposition of potassium ferrocyanide and was invented before the Castner process. There are many different methods among which the most commonly used method of preparing Potassium Cyanide is given below :

  • Hydrogen Cyanide reacts with Potassium Hydroxide which leads to the formation of Potassium Cyanide and Water.

HCN + KOH -> KCN + H₂O

Here in this method, there is a relation between a strong base (KOH) and a weak acid (HCN) which leads to the formation of potassium salt (KCN). 

  • Another method of preparing potassium cyanide is with formamide,


Here in this reaction, a crystalline salt is prepared with the combination of a strong base and weak acid.