Hydrocyanic Acid - HCN

What is Hydrocyanic Acid?

Hydrocyanic acid is a liquid of hydrogen cyanide in water. The chemical formula of Hydrocyanic acid is HCN. Hydrocyanic acid is a colorless liquid whose vapor is lighter than air and dissipates rapidly. It is usually sold commercially as an aqueous solution containing 2 to 10% hydrogen cyanide.The aqueous solutions of hydrogen cyanide decomposes slowly to form ammonium formate. It is very poisonous colourless gas with a characteristic fragrance of bitter almonds. It is a dangerous transparent liquid its storage and transport are prohibited.

Other names – Prussic acid, acetonitrile, formonitrile

HCN Hydrocyanic acid
Density 687 kg/m³
Molecular Weight/ Molar Mass 27.0253 g/mol
Boiling Point 25.6 °C
Melting Point -13.4 °C
Chemical Formula HCN

Hydrocyanic Acid Structure – HCN

Hydrocyanic Acid Structure

Physical Properties of Hydrocyanic Acid – HCN

Odour Bitter almond smell
Appearance Pale blue
Covalently-Bonded Unit 2
Heat capacity 35.9 J K−1 mol−1
Hydrogen Bond Donor 1
Solubility Miscible in water and ethanol

Chemical Properties of Hydrocyanic Acid – HCN

    • Hydrocyanic acid reacts with base like sodium hydroxide forms sodium cyanide and water. The chemical equation is given below.

HCN + NaOH → NaCN + H2O

    • Hydrocyanic acid reacts with potassium hydroxide forms potassium cyanide and water. The chemical equation is given below.

HCN + KOH → H2O + KCN

Uses of Hydrocyanic Acid – HCN

  • Used as a fugiment to kill pests such as rodents in warehouses, grain storage bins, greenhouses and holds of ships where its high toxicity and ability to penetrate obscure spaces are advantageous.
  • Used in the manufacture of cyanide salts, acrylonitrile and dyes. It is also used as a horticultural fumigant.
  • Used as a highly valuable precursor in the production of several chemicals.

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