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Cyanide of potassium
Cyanure de potassium
Hydrocyanic acid, potassium salt
Potassium cyanide (K(CN))
Molecular Formula
MDL Number
Molecular Weight
MOL File

Chemical Properties

Potassium cyanide are white lumps, granular powder, or colorless solution. It may be shipped as capsules, tablets, or pellets. Toxic hydrogen cyanide gas released by potassium cyanide has a distinctive, weak bitter almond odor, but many people cannot detect it; the odor does not provide adequate warning of hazardous concentrations.
white granular powder or crystals
634 °C(lit.)

1625 °C
1.00 g/mL at 20 °C

storage temp. 
Poison room
H2O: 1 M at 20 °C, clear, colorless

Stable. Incompatible with a variety of materials, including acids, iodine, peroxides, permanganates, alkaloids, chloral hydrate, metallic salts. Light and moisture sensitive. Contact with acid generates extremely toxic HCN gas.
Potassium cyanide is a white granular salt made by the absorption of hydrogen cyanide in potassium hydroxide. It is soluble in both water and alcohol and a lethal poison. If mixed with acids it produces highly toxic hydrogen cyanide gas. This was the preferred fixing chemical for collodion positives because it contained no sulfides to darken the highlight silver. As a fixing agent cyanide was particularly effective. After dissolving the unexposed silver halides cyanide would also remove nonimage fog producing very clean shadow areas. Prolonged fixing would eventually remove image silver. Tincture of iodine was added to dilute solutions of potassium cyanide and used to remove unwanted non-image silver in photographic materials and to remove silver stains.
CAS DataBase Reference
151-50-8(CAS DataBase Reference)

Safety Data

Hazard Codes 
Risk Statements 
R26/27/28:Very Toxic by inhalation, in contact with skin and if swallowed .
R32:Contact with acids liberates very toxic gas.
R50/53:Very Toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment .
Safety Statements 
S7:Keep container tightly closed .
S28:After contact with skin, wash immediately with plenty of ... (to be specified by the manufacturer) .
S29:Do not empty into drains .
S45:In case of accident or if you feel unwell, seek medical advice immediately (show label where possible) .
S60:This material and/or its container must be disposed of as hazardous waste .
S61:Avoid release to the environment. Refer to special instructions safety data sheet .
UN 1680 6.1/PG 1

WGK Germany 


HS Code 
Safety Profile
A deadly human poison by ingestion. A experimental poison by ocular, subcutaneous, intravenous, intramuscular, and intraperitoneal routes. Experimental teratogenic and reproductive effects. Human systemic effects by ingestion: convulsions, pulse rate increase. Mutation data reported. Reacts with acids or acid fumes to liberate deadly HCN. When heated to decomposition it emits very toxic fumes of K2O , CN-, and NOx. See also CYANIDE.

Raw materials And Preparation Products

Hazard Information

General Description
White amorphous lumps or a crystalline mass with a faint odor of bitter almonds. Density 1.52 g/cm3 Toxic by skin absorption through open wounds, by ingestion. Heating to decomposition produces toxic fumes. Used for gold and silver extraction, in chemical analysis, to make other chemicals, and as an insecticide.
Reactivity Profile
POTASSIUM CYANIDE(151-50-8) is a basic salt and a reducing agent. Reacts with acids of all kinds to generate poisonous hydrogen cyanide gas. Can react violently with oxidizing agents: fusion with metal chlorates, perchlorates, nitrates, or nitrites can cause explosions [Bretherick 1979. p. 101]. A mixture with perchloryl fluoride may explode above 100°C. A mixture with nitrite salts may cause an explosion [Pieters 1957. p. 30]. Incompatible with iodine. Initiates the explosive decomposition of nitrogen trichloride.
Air & Water Reactions
Deliquescent. Soluble in water. Dissolution releases some poisonous hydrogen cyanide gas. The amount is not hazardous except in an enclosed space. If the water is acidic, dangerous amounts of hydrogen cyanide form at once.
A poison as absorbed by skin.
Health Hazard
Potassium cyanide is a white solid or colorless water solution with a faint bitter almond odor. As a solution, it is slightly soluble in ethanol. It is a poison that reacts with acid or acid fumes to emit deadly hydrogen cyanide. When heated to decomposition, it emits very toxic fumes. As a solid, potassium cyanide is incompatible with nitrogen trichloride, perchloryl fl uoride, sodium nitrite, acids, alkaloids, chloral hydrate, and iodine. A synonym for potassium cyanide is potassium salt of hydrocyanic acid
Health Hazard
POTASSIUM CYANIDE is classified as super toxic. Probable oral lethal dose in humans is less than 5 mg/kg or less than a taste (7 drops) for a 150 lb. person. It is an eye and skin irritant. Poisonous in very small quantities; a taste is lethal.
Potential Exposure
Used in electroplating, steel hardening; extraction of precious metals form ores; as a fumigant; in insecticides; a reagent in analytical chemistry
Fire Hazard
Contact with acid releases highly flammable hydrogen cyanide gas. Moisture may cause this material to volatilize as hydrogen cyanide. When heated to decomposition, POTASSIUM CYANIDE emits very toxic fumes of cyanide and nitrogen oxides. Reacts with acids to produce hydrogen cyanide gas. Reacts with strong oxidizers such as nitrates and chlorates, nitrogen trichloride; perchloryl fluoride; sodium nitrate; acids; alkaloids; chloral hydrate; iodine. Avoid contact with acids.
First aid
If this chemical gets into the eyes, remove any contact lenses at once and irrigate immediately for at least 15 minutes, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts the skin, remove contaminated clothing and wash immediately with soap and water. Speed in removing material from skin is of extreme importance. Shampoo hair promptly if contaminated. Seek medical attention immediately. If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR if heart action has stopped. Transfer promptly to a medical facility. When this chemical has been swallowed, get medical attention. Give large quantities of water and induce vomiting. Do not make an unconscious person vomit. Keep under observation for 2448 hours as symptoms may return. Use amyl nitrate capsules if symptoms develop. All area employees should be trained regularly in emergency measures for cyanide poisoning and in CPR. A cyanide antidote kit should be kept in the immediate work area and must be rapidly available. Kit ingredients should be replaced every 12 years to ensure freshness. Persons trained in the use of this kit; oxygen use, and CPR must be quickly available.
UN1680 Potassium cyanide, Hazard Class: 6.1; Labels: 6.1-Poisonous materials.
A strong reducing agent; keep away from oxidizers. Potassium cyanide decomposes on contact with water, humidity, carbon dioxide, strong acids (such as hydrochloric, sulfuric, and nitric acids), and acid salts, producing highly toxic and highly flammable hydrogen cyanide gas. Potassium cyanide absorbs water from air (is hygroscopic or deliquescent); the aqueous solution is a strong base. Incompatible with organic anhydrides; isocyanates, alkylene oxides; epichlorohydrin, aldehydes, alcohols, glycols, phenols, cresols, caprolactum, strong oxidizers; nitrogen trichloride; sodium chlorate. Attacks aluminum, copper, zinc in the presence of moisture.
Waste Disposal
Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal. In accordance with 40CFR165, follow recommendations for the disposal of pesticides and pesticide containers. Must be disposed properly by following package label directions or by contacting your local or federal environmental control agency, or by contacting your regional EPA office. Add strong alkaline hypochlorite and react for 24 hours. Then flush to sewer with large volumes of water.

Material Safety Data Sheet(MSDS)

Questions And Answer

Potassium cyanide (KCN) is a white crystalline substance with a slight odor of bitter almonds. It is produced when hydrogen cyanide is absorbed in potassium hydroxide. It is used to extract gold and silver from their ores, in electroplating computer boards, and as an insecticide. Potassium cyanide is very toxic to the skin or when ingested or inhaled, and it is used as a source of cyanide (CN) gas in gas chambers.

Potassium cyanide, in addition to processes already described, can be prepared by the reaction of potassium carbonate with calcium hexacyanoferrate(II) or by thermal decomposition of K4Fe(CN)6 above 435°C. Rubidium and cesium cyanides can be prepared by the reaction of HCN with the metal hydroxides in alcohol or ether or with the corresponding metals in anhydrous ether or benzene. Hydrogen reduction of metal cyanates produces water and the corresponding cyanide, as does reduction with carbon monoxide.

Spectrum Detail

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