Names | |
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IUPAC name
Potassium cyanide
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Identifiers | |
151-50-8 | |
3D model (Jmol) | Interactive image |
ChEBI | CHEBI:33191 |
ChemSpider | 8681 |
ECHA InfoCard | 100.005.267 |
EC Number | 205-792-3 |
PubChem | 9032 |
RTECS number | TS8750000 |
UNII | MQD255M2ZO |
UN number | 1680 |
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Properties | |
KCN | |
Molar mass | 65.12 g/mol |
Appearance | White crystalline solid deliquescent |
Odor | faint, 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) |
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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/100mL |
Solubility in hydroxylamine | 41 g/100 mL |
Acidity (pKa) | 11.0 |
−37.0·10−6 cm3/mol | |
Refractive index (nD)
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1.410 |
Thermochemistry | |
Std molar
entropy (S |
127.8 J K−1 mol−1 |
Std enthalpy of
formation (ΔfH |
−131.5 kJ/mol |
Hazards | |
Safety data sheet | ICSC 0671 |
GHS pictograms | |
GHS signal word | Danger |
H290, H300, H310, H330, H370, H372, H410 | |
P260, P264, P273, P280, P284, P301+310 | |
EU classification (DSD)
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T+ N |
R-phrases | R26/27/28, R32, R50/53 |
S-phrases | (S1/2), S7, S28, S29, S45, S60, S61 |
NFPA 704 | |
Flash point | Non-flammable |
Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
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5 mg/kg (oral, rabbit) 10 mg/kg (oral, rat) 5 mg/kg (oral, rat) 8.5 mg/kg (oral, mouse) |
US health exposure limits (NIOSH): | |
PEL (Permissible)
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TWA 5 mg/m3 |
REL (Recommended)
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C 5 mg/m3 (4.7 ppm) [10-minute] |
IDLH (Immediate danger)
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25 mg/m3 |
Related compounds | |
Other anions
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Potassium cyanate Potassium thiocyanate |
Other cations
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Sodium cyanide |
Related compounds
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Hydrogen cyanide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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what is ?) | (|
Infobox references | |
Potassium cyanide is a compound with the formula KCN. This colorless crystalline salt, similar in appearance to sugar, is highly soluble in water. Most KCN is used in gold mining, organic synthesis, and electroplating. Smaller applications include jewelry for chemical gilding and buffing.
Potassium cyanide is highly toxic. The moist solid emits small amounts of hydrogen cyanide due to hydrolysis, which smells like bitter almonds. Not everyone, however, can smell this; the ability to do so is a genetic trait.
The taste of potassium cyanide has been described as acrid with a burning sensation.
KCN is produced by treating hydrogen cyanide with aqueous solution of potassium hydroxide, followed by evaporation of the solution in a vacuum:
or by treating formamide with potassium hydroxide:
About 50,000 tons of potassium cyanide are produced yearly.
Prior to 1900 AD, before the invention of the Castner process, potassium cyanide was the most important source of alkali metal cyanides. In this historical process, potassium cyanide was produced by decomposing potassium ferrocyanide: