Potassium Cyanide Formula || What does Cyanide do to the body?

White globular lumps, granular or crystalline powder, highly toxic. It deliquesces in humid air and emits traces of hydrogen cyanide gas. Easily 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. 

Potassium Cyanide Formula: KCN

Contact with skin wounds or inhalation of trace amounts of powder can poison death. Decomposition by contact with acid can release highly toxic hydrogen cyanide gas, and it can explode when mixed with chlorate or sodium nitrite.


Regulatory information

Potassium cyanide (very toxic ) ( XZ )

This product is controlled by the public security department according to the ” Dangerous Chemicals Safety Management Regulations “.

Physical and chemical properties

Physical properties

Appearance and properties: white crystal or powder, easily deliquescence, the smell of hydrogen cyanide (bitter almond smell)

  • Relative density (water = 1): 1.52
  • Melting point: 634 ° C
  • pH (0.1mol / L): 11.0
  • Saturated vapor pressure (kPa): Not available
  • The heat of combustion (kJ / mol): meaningless
  • Critical temperature (℃): meaningless
  • Critical pressure (MPa): meaningless
  • The logarithm of the octanol/water partition coefficient: Not available
  • Flashpoint (°C): meaningless
  • Upper explosion limit% (V / V): meaningless
  • Ignition temperature (° C): meaningless
  • Lower explosion limit% (V / V): meaningless
  • Solubility: Easily soluble in water, ethanol, glycerol, slightly soluble in methanol, sodium hydroxide aqueous solution.

Chemical properties

Deterioration in the air

2KCN + CO2 + H2O = 2HCN + K2CO3

2. The aqueous solution is easy to deteriorate


Function and use

And sodium cyanide for the same purpose can be common. Compared with sodium cyanide, it has the advantages of high conductivity and fine coating when it is electroplated. It is more suitable for use, but it is 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, etc.

Precautions for use

Health hazard

Invasion: inhalation, ingestion, percutaneous absorption.

Health hazard: Inhibition of respiratory enzymes, causing intracellular suffocation. Acute poisoning can be caused by inhalation, oral or transdermal absorption. Sudden death can be caused by oral administration of 50 to 100 mg. Non-sudden death patients are clinically divided into 4 stages: 


prodromal period with mucosal irritation, deepening of breathing, fatigue, headache, oral tongue tip, oral numbness, etc.

dyspnea, breathing difficulty, elevated blood pressure, bright red skin, etc. 

Seizures, coma, and respiratory failure occurred during the convulsions; muscles were loosened during the paralysis period, and respiratory heartbeat stopped and died. Prolonged exposure to small amounts of cyanide causes neurasthenia syndrome, eye and upper respiratory tract irritation. It can cause a rash.

Toxicological information and environmental behavior

Toxicity: Highly toxic.

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


DNA suppression: mouse lymphocytes 1 nmol / L.

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

Source of pollution: Cyanide is a highly toxic substance. 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 urine, saliva, sweat, etc.

Free cyano groups can also be combined within Vivo cobalt-containing compounds (such as hydroxycobalamin ) to form non-toxic cobalt cyano compounds. Therefore, clinical reports of hydroxycobalamin or cobaltate edetate to rescue CN-acute poisoning are useful.

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

Cyanide is very unstable in surface water. When the pH of the water is greater than 7 and the presence of oxygen, it can be oxidized to form carbonates and ammonia. Surface water contains microorganisms that can decompose and use cyanide and can also convert cyanide to carbonate and ammonia through biological oxidation.

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

The soil has a strong ability to purify cyanide. Except for the cyanide entering the soil, which escapes into the air, part of it is absorbed by plants and is assimilated or oxidized in the plants. It remains in the soil and is partially converted to carbonates, ammonia, and formate by the action of microorganisms. 

When cyanide continues to be contaminated, soil microorganisms can acclimate and produce suitable microflora after domestication, which plays a huge role in the purification of cyanide. Therefore, in some areas where low-concentration cyanide-containing industrial wastewater was subjected to long-term sewage irrigation, the cyanide content in the soil hardly accumulated.

Residue and accumulation: The natural world has a strong purification effect on cyanide pollution. Therefore, in general, exogenous cyanide is not easy to accumulate in the environment and the body. Only under specific conditions (accidental discharge, high-level continuous pollution), when the amount of cyanide pollution exceeds the purification capacity of the environment, it can remain and accumulate in the environment, posing a potential hazard to people and organisms.

Migration and transformation: Cyanide is widely present in nature. Animals and plants all contain some cyanide substances. Some plants such as bitter almonds, ginkgo, nuts, cassava, sorghum, etc. contain considerable amounts of cyanogenic glycosides. It releases hydrogen cyanide after hydrolysis, and trace cyanide can also be detected in some common grains and vegetables.

Cyanide is also commonly found in soil and decreases with increasing soil depth, and its content is 0.003-0.130 mg/kg. The cyanide in natural soil comes mainly 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 microorganisms, cyanide and phenol can be generated, so the background content of cyanide in the soil is closely related to the content of organic matter in it.

Due to hydrogen cyanide and its volatility, most cyanide is easily soluble in water, so the cyanide discharged into the natural environment is easily diluted, diffused by water (or the atmosphere), and has strong migration ability. Hydrogen cyanide and simple cyanide are very unstable in surface water, and hydrogen cyanide easily escapes into the air; or when the pH of the water is greater than 7 and the presence of oxygen, it can also be oxidized to form carbonates and ammonia.

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

Hydrogen cyanide has a bitter almond odor, which is easily diffused and easily soluble in water to form hydrocyanic acid. Cyanide is generally colorless crystals. It is prone to deliquescent in the air and has a weak odor of hydrogen cyanide. The water produces almond odor.

Symptoms of poisoning: mild cases with mucous membrane irritation, numbness, headache, dizziness, weakness in the lower limbs, chest compression, nausea, vomiting, increased blood pressure, palpitations, asthma, etc. Severe breathing is irregular, and gradually coma, convulsions, incontinence, decreased blood pressure, rapid respiratory failure and death.

Hazardous characteristics: Non-combustible. High heat or contact with acids can produce highly toxic cyanide gas. Reacts violently with nitrate, nitrite, and chlorate, posing the risk of explosion. It can absorb water and carbon dioxide in the presence of acid or exposed air, and decompose into highly toxic hydrogen cyanide. The aqueous solution is an alkaline corrosive liquid.

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

Emergency Response

Wear gas masks and gloves to handle spills, sweep up, and pour into a large amount of water. Add an excess of sodium hypochlorite or bleaching powder and leave it for 24 hours to confirm that all cyanide is decomposed.

After dilution, put it into the wastewater system. After the contaminated area is soaked with 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 a wastewater system for unified treatment. 

For hydrogen cyanide, the gas should be sent to a fume hood or introduced into a sodium carbonate solution, and an equal amount of sodium hypochlorite should be added to neutralize it with a 6mol / L sodium hydroxide solution.

Protective measures

Respiratory protection: When it is possible to come into contact with the poison, you must wear a hood-type electric air supply filter dust-proof respirator. When exposed to dust, wear an isolated respirator.

Eye protection: Protection has been done in respiratory protection.

Body protection: Wear protective clothing with protective tape.

Hand protection: Wear rubber gloves.

Others: Smoking, eating and drinking are not allowed on the job site. After work, wash thoroughly. The workshop should be equipped with first aid equipment and medicines. Store clothes contaminated by poisons separately and wash them for later use. Operators should learn to save themselves and each other.


Skin contact: Remove contaminated clothing immediately, rinse thoroughly with running water or 5% thiosulfuric acid solution for at least 20 minutes, and consult a doctor.

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

Inhalation: Quickly leave the scene to fresh air. Keep your airways open. If breathing is difficult, give oxygen. When breathing is stopped, immediately perform artificial respiration (do not use mouth to mouth) and chest compressions. Give inhaled isoamyl nitrite and seek medical attention.

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

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

Fire extinguishing agents: dry powder, sandy soil, carbon dioxide and acid and alkali fire extinguishing agents are prohibited.

Sanjay Bhandari

Hello Friends, My name is Sanjay Bhandari. I am a chemistry Teacher.

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