Potassium cyanide
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| Potassium cyanide | |
|---|---|
| Molecular formula | KCN |
| Molar mass | 65.12 g/mol |
| CAS number | [151-50-8] |
| EINECS number | 205-792-3 |
| Density | 1.52 g/cm3 |
| Solubility (water) | 71.6 g/100 ml (25°C) |
| Melting point | 634°C |
| Thermodynamic data | |
| Standard enthalpy of formation ΔfH°solid | −131.5 kJ/mol |
| Standard molar entropy S°solid | 127.8 J.K–1.mol–1 |
| Hazards | |
| MSDS | External MSDS |
| EU classification | Very toxic (T+) Dangerous for the environment (N) |
| R-phrases | R26/27/28, R32 R50/53 |
| S-phrases | S1/2, S7, S28, S29 S45, S60, S61 |
| PEL (US: OSHA) | 5 mg/m3 (TWA) (as CN) |
| IDLH (US: OSHA) | 25 mg/m3 (as CN) |
| RTECS number | TS8750000 |
| Supplementary data page | |
| Structure and properties | n, εr, etc. |
| Thermodynamic data | Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Other cations | Sodium cyanide |
| Related compounds | Hydrogen cyanide |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) [Chemical infoboxInfobox disclaimer and references] | |
Potassium cyanide or KCN is the potassium salt of hydrogen cyanide or hydrocyanic acid. It is a colorless crystalline compound, similar in appearance to sugar, and highly soluble in water. Highly toxic, KCN has a smell like bitter almonds, but not everyone can smell it. It is one of the few substances that form soluble compounds with gold, and thus is used in jewelry for chemical gilding and buffing. It can be used in gold mining to extract the metal from ores, although sodium cyanide is more commonly used. KCN was sometimes used as a rat poison until the 1970s.
Toxicity
Cyanide salts are among the most rapidly acting of all known poisons. Cyanide is a potent inhibitor of respiration, acting on mitochondrial cytochrome oxidase and hence blocking electron transport. This results in decreased oxidative metabolism and oxygen utilization. Lactic acidosis then occurs as a consequence of anaerobic metabolism. Initially, acute cyanide poisoning causes a red or ruddy complexion in the victim because the tissues are not able to use the oxygen in the blood.
The effects of potassium cyanide are similar to sodium cyanide. Once more than 100–200 mg of potassium cyanide is consumed, consciousness is lost within one minute, sometimes within 10 seconds, depending on the strength of the body's immunity and the amount of food present in the stomach. After a span of about 45 minutes, the body goes into a state of coma or deep sleep and the person may die within two hours if not treated medically. During this period, convulsions may occur. Death occurs mainly by cardiac arrest.
Several prominent Nazis, including Hermann Goering and Heinrich Himmler, used potassium cyanide to commit suicide. The substance was also used in the 1978 mass murder/suicide of more than 900 people at Jonestown, Guyana.
Potassium cyanide in fiction
Potassium cyanide (and other forms of cyanide) often appear in fiction. In crime fiction it is a popular choice as a murder weapon; in spy fiction captured agents often use cyanide pills to commit suicide as in the James Bond movie Dr. NoPotassium cyanide was also featured in the novel and movie Battle Royale. Provided with a sample of the substance to use as a weapon, one of the female characters employs the toxin to poison the soup of another character. The tainted food reaches an unintended recipient however, triggering the events in the infamous lighthouse scene.
Source
- Institut national de recherche et de sécurité (1997). "[Cyanure de sodium. Cyanure de potassium]". Fiche toxicologique n° 111, Paris:INRS, 6pp. (PDF file, in French)
See also
External links
- [International Chemical Safety Card 0671]
- [Hydrogen cyanide and cyanides] (CICAD 61)
- [National Pollutant Inventory - Cyanide compounds fact sheet]
- [NIOSH Pocket Guide to Chemical Hazards]
- [European Chemicals Bureau]
- [CSST (Canada)]
- [NIST Standard Reference Database]
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