Educational Guide on the Chemistry of Sodium Cyanide

Sodium cyanide (NaCN) is a chemical compound that combines sodium (Na) and cyanide (CN), an ion composed of carbon and nitrogen linked by a triple bond. It is a white, water-soluble solid that possesses a high affinity for metals, which makes it extremely useful in industries such as mining, particularly in the extraction of gold and silver. However, its high toxicity also makes it one of the most dangerous chemicals in use, demanding strict handling and safety protocols.

Chemical Properties of Sodium Cyanide

Sodium cyanide is an ionic compound with a crystalline structure. It readily dissolves in water to produce sodium ions (Na+) and cyanide ions (CN-). The cyanide ion acts as a pseudohalide and is highly reactive, particularly towards transition metals.

Molecular Weight: Sodium cyanide has a molecular weight of 49.01 g/mol.

Melting and Boiling Points: It has a melting point of 563.7 degrees Fahrenheit (295.4 degrees Celsius) and decomposes upon heating before reaching its boiling point.

Solubility: Sodium cyanide is quite soluble in water and also soluble in alcohol. Its high solubility in water makes it particularly hazardous as it can easily contaminate water sources.

Stability: Sodium cyanide is stable under normal conditions but releases highly toxic hydrogen cyanide gas when reacted with acidic substances or heated to decomposition.

Reactions with Other Substances

  1. Reaction with Acids: Sodium cyanide reacts violently with strong acids to produce hydrogen cyanide (HCN), a highly toxic and volatile gas. This reaction is a major risk factor when dealing with NaCN, especially in the presence of water and acid.++NaCN+HClNaCl+HCN
  2. Complexation with Metals: In the presence of transition metals, NaCN forms strong coordination complexes. For example, in the cyanidation process used in mining, NaCN reacts with gold and silver to form soluble complexes which can then be extracted.
  3. Reaction with Carbon Dioxide: Sodium cyanide can react with carbon dioxide in water to form sodium bicarbonate and hydrogen cyanide, which is a consideration for environmental exposure and contamination.

Applications and Uses

Despite its dangers, sodium cyanide’s ability to form complexes with metals makes it invaluable in certain industrial processes:

  • Mining: Used in the extraction of gold and silver from ores through the process of cyanidation.
  • Chemical Synthesis: Used in the production of organic compounds such as nitriles and carboxylic acids.
  • Electroplating: Used in cadmium and zinc electroplating for the formation of metal coatings.

Toxicity and Safety Concerns

The primary reason sodium cyanide is dangerous is due to its high toxicity. Exposure can occur through inhalation, ingestion, or skin contact. The cyanide ion inhibits cellular respiration by binding irreversibly to the iron atom in the cytochrome oxidase enzyme, effectively stopping the production of ATP (adenosine triphosphate) and leading to cell death.

Symptoms of Cyanide Poisoning:

  • Headache, dizziness, confusion
  • Shortness of breath, respiratory failure
  • Cardiac arrest, seizures

Due to its potential for harm, handling sodium cyanide requires stringent safety measures. These include the use of personal protective equipment (PPE), proper ventilation systems, and training for emergency response to cyanide exposure.


Sodium cyanide is a compound with significant industrial utility, particularly in mining. However, its highly toxic nature requires that it be handled with the utmost care. Understanding the chemical properties, reactions, and safety measures associated with sodium cyanide can help prevent accidents and ensure safe usage in various industrial applications. This guide serves both educational and practical purposes, aiming to enhance awareness and knowledge about this potent chemical, thereby safeguarding human health and the environment.

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