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 colourless liquid whose vapour 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 decompose slowly to form ammonium formate. It is a 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
Table of Contents
- Lewis Structure of Hydrogen cyanide – HCN
- Chemical data of Hydrogen cyanide-HCN
- Physical Properties of Hydrogen cyanide – HCN
- Chemical Properties of Hydrogen cyanide – HCN
- Uses of Hydrogen cyanide – HCN
- Frequently Asked Questions
Lewis Structure of Hydrogen cyanide – HCN
Chemical data of Hydrogen Cyanide-HCN
| 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 |
Physical Properties of Hydrogen cyanide-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 Hydrogen cyanide-HCN
- Hydrocyanic acid reacts with bases 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 Hydrogen cyanide-HCN
- Used as a fumigant 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.
Frequently Asked Questions- FAQs
1. Is hydrocyanic acid harmful?
Hydrocyanic acid is one of the most rapidly acting poisons, and it is therefore used especially as a suicidal or homicidal agent. Small concentrations of hydrocyanic acid are inhaled, causing headache, dizziness, feeling of suffocation, nausea, etc.
2. Is hydrogen cyanide still used?
Hydrogen cyanide is used in the manufacture of cyanide salts, acrylonitrile and dyes. It is also used as a horticultural fumigant. It is used commercially for fumigation, electroplating, mining, chemical synthesis, and the production of synthetic fibres, plastics, dyes, and pesticides.
3. What is the molecular shape of HCN?
The molecular shape of HCN is linear.
4. What is the hybridization of HCN?
In HCN structure the hybridisation of carbon atom is sp hybridisation. There are two sigma bonds, C-H and C-N. The number of sigma bonds is equal to the number of hybrid orbitals formed.
5. Is HCN a strong or weak acid?
HCN is a weak acid. A weak acid has a strong conjugate base. CN- is a strong conjugate base.
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