Potassium cyanide
| Names | |
|---|---|
| IUPAC name
Potassium cyanide | |
| Identifiers | |
3D model (JSmol) |
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| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.005.267 |
| EC Number |
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PubChem CID |
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| RTECS number |
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| UNII | |
| UN number | 1680 |
CompTox Dashboard (EPA) |
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| Properties | |
| KCN | |
| Molar mass | 65.12 g/mol |
| Appearance | White crystalline solid deliquescent |
| Odor | faint, bitter almond-like |
| Density | 1.52 g/cm3 |
| Melting point | 634.5 °C (1,174.1 °F; 907.6 K) |
| Boiling point | 1,625 °C (2,957 °F; 1,898 K) |
| 71.6 g/100 ml (25 °C) 100 g/100 ml (100 °C) | |
| Solubility in methanol | 4.91 g/100 ml (20 °C) |
| Solubility in glycerol | soluble |
| Solubility in formamide | 14.6 g/100 ml |
| Solubility in ethanol | 0.57 g/100 ml |
| Solubility in hydroxylamine | 41 g/100 ml |
| Acidity (pKa) | 11.0 |
| −37.0·10−6 cm3/mol | |
Refractive index (nD) |
1.410 |
| Thermochemistry | |
Std molar entropy (S⦵298) |
127.8 J K−1 mol−1 |
Std enthalpy of formation (ΔfH⦵298) |
−131.5 kJ/mol |
| Hazards | |
| GHS labelling: | |
| Danger | |
| H290, H300, H310, H330, H370, H372, H410 | |
| P260, P264, P273, P280, P284, P301+P310 | |
| NFPA 704 (fire diamond) | |
| Flash point | Non-flammable |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose) |
5 mg/kg (oral, rabbit) 10 mg/kg (oral, rat) 5 mg/kg (oral, rat) 8.5 mg/kg (oral, mouse) |
| NIOSH (US health exposure limits): | |
PEL (Permissible) |
TWA 5 mg/m3 |
REL (Recommended) |
C 5 mg/m3 (4.7 ppm) [10-minute] |
IDLH (Immediate danger) |
25 mg/m3 |
| Safety data sheet (SDS) | ICSC 0671 |
| Related compounds | |
Other anions |
Potassium cyanate Potassium thiocyanate |
Other cations |
Sodium cyanide Rubidium cyanide lithium cyanide caesium cyanide |
Related compounds |
Hydrogen cyanide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references | |
Potassium cyanide is a compound with the formula KCN. It is a colorless salt, similar in appearance to sugar, that is highly soluble in water. Most KCN is used in gold mining, organic synthesis, and electroplating. Smaller applications include jewellery for chemical gilding and buffing. Potassium cyanide is highly toxic, and a dose of 200 to 300 milligrams will kill nearly any human.
The moist solid emits small amounts of hydrogen cyanide due to hydrolysis (reaction with water). Hydrogen cyanide is often described as having an odor resembling that of bitter almonds.
The taste of potassium cyanide has been described as acrid and bitter, with a burning sensation similar to lye. However, potassium cyanide kills so rapidly its taste has not been reliably documented. In 2006, an Indian man named M.P. Prasad committed suicide using potassium cyanide. He was a goldsmith and was aware of the mystery behind its taste. In the suicide note Prasad left, the final words written were that potassium cyanide "burns the tongue and tastes acrid", but for obvious reasons this description has not been independently confirmed.