Potassium cyanide is white spherical hard block, granular or crystalline powder, highly toxic. Deliquescent in humid air and release a small amount of hydrogen cyanide gas. Soluble in water, slightly soluble in alcohol, the aqueous solution is strongly alkaline and quickly hydrolyzed.

The density is 1.857 g/cm^3, the boiling point is 1497°C, and the melting point is 563°C. It can be poisoned and died by touching the skin wound or inhaling a small amount of powder.

Decomposition with acid can release highly toxic hydrogen cyanide gas, which can be exploded by mixing with chlorate or sodium nitrite.

Potassium cyanide

Potassium Cyanide Formula

Alias: Kasumi

Chemical formula: KCN

Relative molecular mass: 65.12

Chemical category: Inorganic material – cyanide

Type of regulation: Potassium cyanide (very toxic) (XZ)

Storage: Sealed dry and protected from light

The X-ray Structure of Potassium Cyanide

Introduction of Potassium Cyanide

Regulatory information

Potassium cyanide (very toxic) (XZ)

The product is regulated by the public security department in accordance with the Regulations on the Safety Management of Hazardous Chemicals.

CAS number


Physical and chemical properties

Physical properties

Appearance and traits: white crystal or powder, easy to deliquesce, the smell of hydrogen cyanide (bitter almond smell)

Relative density (water = 1): 1.52

Melting point: 634 ° C

pH (0.1 mol / L): 11.0

Saturated vapor pressure (kPa): No data available

Combustion heat (kJ/mol): meaningless

Critical temperature (°C): meaningless

Critical pressure (MPa): meaningless

Logarithm of the octanol/water partition coefficient: no data available

Flashpoint (°C): meaningless

Upper explosion limit % (V/V): meaningless

Ignition temperature (°C): meaningless

Lower explosion limit % (V/V): meaningless

Solubility: Soluble in water, ethanol, glycerin, slightly soluble in methanol, sodium hydroxide solution.

The Facts About Cyanides

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Chemical properties

Deterioration in the air


The aqueous solution is easy to deteriorate


Potassium cyanide

Function and Use

It is the same as sodium cyanide and can be used universally. In more sodium cyanide plating further has a highly conductive property, fine coating, etc., more appropriate to use, but more expensive.

Used for ore flotation to extract gold and silver. Heat treatment of steel to produce organic nitriles. Analytical chemistry is used as a reagent. In addition, it is also used for photography, etching, lithography, and the like.

Precautions for use

Health hazard

Routes of entry: inhalation, ingestion, percutaneous absorption.

Health hazard: inhibits respiratory enzymes and causes intracellular asphyxia. Acute poisoning can be caused by inhalation, oral administration or percutaneous absorption.

Oral administration of 50 ~ 100mg can cause sudden death. The non-sudden death is divided into 4 stages: mucosal stimulation in the prodromal period, deepening of breathing, fatigue, headache, oral tip, oral numbness, etc.; difficulty breathing during breathing, elevated blood pressure, bright red skin, and mucous membranes.

How Does Cyanide Kill?

During convulsions, convulsions, coma, and respiratory failure occurred; during the paralysis period, the whole body muscles were slack, and the respiratory heartbeat stopped and died. Long-term exposure to small amounts of cyanide causes neurasthenia syndrome, eye, and upper respiratory tract irritation. Can cause a rash.

Toxicological information and environmental behavior

Toxicity: Highly toxic.

Acute toxicity: LD506.4mg/kg (rat oral); 8500μg/kg (mouse oral)


DNA inhibition: mouse lymphocytes 1 nmol / L.

Cytogenetic analysis: mouse mammary gland 1nmol/L, 48 hours.

Sources of pollution: Cyanide is a highly toxic substance, and its pollution accidents often occur in the production process of electroplating, alchemy, heat treatment, gas, cooking, tanning, plexiglass, benzene, toluene, xylene, photography, and pesticides.

Metabolism and degradation: free cyano in vivo metabolic pathway is the enzyme thiocyanate (or β-mercapto-pyruvate transferase enzyme) catalysis, the sulfur from the addition reaction, conversion into low toxicity SCN (only CN – 1/200 of toxicity). It is then excreted from the body by urine, saliva, sweat, and the like.

The free cyano group can also be combined with a cobalt-containing compound such as hydroxycobalamin to form a non-toxic cyanide compound. Therefore, the clinical use of hydroxycobalamin or dicobalt citrate to rescue CN-acute poisoning reports.

The human body has a strong detoxification function for CN-, and cyanide is a non-accumulative poison. When a small amount of exogenous cyanide that does not cause a toxic dose enters the body, it can be quickly converted into non-toxic or low-toxic substances and excreted.

Cyanide is very unstable in surface water and can be oxidized to form carbonate and ammonia when the pH of the water is greater than 7 and in the presence of oxygen. There are microorganisms in the surface water that can decompose cyanide, and cyanide can be converted into carbonate and ammonia by bio-oxidation.

Therefore, the self-cleaning process of cyanide in the surface water is quite rapid, but the self-purification process of cyanide in water is affected by water temperature, aeration degree (stirring), pH, water surface size and depth.

Potassium cyanide

The soil has a strong ability to purify cyanide. Cyanide entering the soil, in addition, to escape into the air, is partially absorbed by plants and assimilated or oxidatively decomposed in plants. It remains in the soil and is partially converted to carbonate, ammonia, and formate by the action of microorganisms.

When cyanide continues to be contaminated, the soil microorganisms are domesticated and sputum can produce a suitable microbial population, which plays a huge role in the purification of cyanide.

Therefore, in some areas where low-concentration cyanide-containing industrial wastewater is used for long-term sewage irrigation, the cyanide content in the soil is hardly accumulated.

Residues and accumulation: The natural environment has a strong purifying effect on cyanide pollution. Therefore, it is generally difficult for exogenous cyanide to accumulate in the environment and the body.

Only under certain conditions (accident discharge, high concentration, and continuous pollution), when the amount of cyanide pollution exceeds the environmental purification capacity, it can remain and accumulate in the environment, thus posing a potential hazard to humans and organisms.

Migration and transformation: Cyanide is widely found in nature. Animals and plants contain some cyanide substances, and some plants such as bitter almond, ginkgo, nuts, cassava, sorghum, etc. contain considerable amounts of the cyanogenic glycoside.

After it is hydrolyzed, it releases the hydrogen cyanide, and in some common grains and vegetables, traces of cyanogen are also detected.

Cyanide is also commonly found in soils and decreases with increasing soil depth, with the content of 0.003-0.130 mg/kg.

Cyanide in natural soils is mainly derived from soil humus. Humus is a complex class of organic compounds whose core is polymerized from polyphenols and contains a certain amount of nitrogen compounds.

Under the action of soil microbes, cyanide and phenol can be formed, so the background content of cyanide in the soil is closely related to the content of organic matter.

Due to hydrogen cyanide and volatile, most cyanide is easily soluble in water, so cyanide discharged into the natural environment is easily diluted and diffused by water (or the atmosphere), and has strong migration ability.

Hydrogen cyanide and simple cyanide are very unstable in surface water, hydrogen cyanide easily escapes into the air; or when the pH of water is greater than 7 and in the presence of oxygen, it can also be oxidized to form carbonate and ammonia.

Simple cyanide is easily hydrolyzed in water to form hydrogen cyanide. If the water contains inorganic acid, even carbon dioxide produced by dissolving carbon dioxide in water can accelerate the decomposition process.

Hydrogen cyanide is a bitter almond flavor, which is easily diffused and easily soluble in water to form hydrocyanic acid. Cyanide is generally colorless crystal, which is deliquescent in air and has a weak odor of hydrogen cyanide. Water produces almond stink.

Symptoms of poisoning: mild mucous membrane irritation, numb headache, dizziness, weakness of the lower limbs, chest pressure, nausea, vomiting, blood pressure, palpitations, asthma, etc. Severe breathing is irregular, gradually coma, paralysis, incontinence, blood pressure, rapid respiratory failure, and death.

Hazardous characteristics: Not flammable. Highly heated or in contact with acid can produce highly toxic cyanide gas. It reacts violently with nitrates, nitrites, and chlorates, posing a risk of explosion. It can absorb water and carbon dioxide in the presence of acid or exposed air and decomposes highly toxic hydrogen cyanide. The aqueous solution is an alkaline corrosive liquid.

Combustion (decomposition) products: hydrogen cyanide, nitrogen oxides.

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Leakage Emergency Treatment

To prevent spills, you must wear gas masks and gloves, sweep them up, and pour them into plenty of water. Add excess sodium hypochlorite or bleaching powder and leave it for 24 hours to confirm that the cyanide is completely decomposed, diluted and placed in the wastewater system.

After the contaminated area is immersed in sodium hypochlorite solution or bleaching powder for 24 hours, it is rinsed with a large amount of water, and the washing water is put into the wastewater system for uniform treatment. Potassium Cyanide

For hydrogen cyanide, the gas should be sent to the fume hood or the gas should be introduced into the sodium carbonate solution, the same amount of sodium hypochlorite should be added, neutralized with 6 mol/L sodium hydroxide solution, and the sewage should be put into the wastewater system for unified treatment.

Protective Measures

Respiratory protection: A hood-type powered air-purifying dust-proof respirator must be worn when exposed to poison. An isolated respirator should be worn when exposed to dust.

Eye protection: Protected from respiratory system protection.

Body protection: Wear protective clothing tape.

Hand protection: Wear rubber gloves.

Other: Smoking, eating, and drinking are prohibited at the job site. After work, thoroughly clean. The workshop should be equipped with first aid equipment and medicines. Store clothes contaminated with poisons separately and wash them for later use. Operators should learn to save themselves from each other.

Potassium Cyanide First-aid

Skin contact: Immediately remove contaminated clothing and rinse thoroughly with running water or 5% thiosulfuric acid solution for at least 20 minutes.

Eye contact: Immediately lift eyelids and rinse thoroughly with plenty of running water or saline for at least 15 minutes. Seek medical attention.

Inhalation: Remove quickly from the scene to fresh air. Keep the airway open. If breathing is difficult, give oxygen. When the heartbeat stops, immediately perform artificial respiration (do not use mouth-to-mouth) and chest compressions. For inhalation of isoamyl nitrite, seek medical attention.

Ingestion: Drink plenty of warm water, induce vomiting, and gastric lavage with 1:5000 potassium permanganate or 5% sodium thiosulfate solution. Seek medical attention.

Firefighting methods: Firefighters must wear special protective clothing for the body.

Extinguishing media: dry powder, sand, it is forbidden to use carbon dioxide and acid and alkali fire extinguishing agents.