Potassium cyanide
| Names | |
|---|---|
| IUPAC name
Potassium cyanide
| |
| Properties | |
| KCN | |
| Molar mass | 65.12 g/mol |
| Appearance | White solid |
| 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) | |
| Solubility | Soluble in glycerol |
| Solubility in ethanol | 0.57 g/100 ml |
| Solubility in formamide | 14.6 g/100 ml |
| Solubility in hydroxylamine | 41 g/100 ml |
| Solubility in methanol | 4.91 g/100 ml (20 °C) |
| Acidity (pKa) | 11.0 |
| 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 | Sigma-Aldrich |
| 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) |
| Related compounds | |
| Related compounds
|
Sodium 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.
Contents
Properties
Chemical
Potassium cyanide can be oxidized to potassium cyanate.
Physical
Potassium cyanide is a white solid soluble in water.
Availability
Chemical suppliers may sell potassium cyanide, however, due to its high toxicity it's almost impossible to get hold of.
Preparation
There are several ways to produce potassium cyanide.
One route involves melting urea with potassium hydroxide. This gives potassium cyanate. Crush the resulting solid and grind it. Mix it with a reducing agent, such as carbon or magnesium to make a thermite-like mixture. Ignite it to reduce the potassium cyanate to potassium cyanide and magnesium or carbon oxides. This route gives impure potassium cyanide which needs to be purified.
A different route involves treating formamide with potassium hydroxide.
Decomposition of potassium ferrocyanide also gives potassium cyanide.
Another more dangerous route involves the acidification of Prussian blue to give hydrogen cyanide which is bubbled to a cooled solution of potassium hydroxide. This gives crude potassium cyanide which can be purified by recrystallization.
Projects
Handling
Safety
Potassium cyanide is highly toxic. Ingestion can lead to death. Lethal dose for an average weight person is considered to be between 200–300 mg.
Storage
Potassium cyanide should be stored in closed bottles, away from any acids, in a locked cabinet with a clear hazard label on the storage bottle.
Disposal
Can be destroyed by oxidizing it with excess bleach or hydrogen peroxide to potassium cyanate.
