Rodanid potassium - a poisonous substance used in analytical chemistry

Rodanid potassium (according to the modern nomenclature of IUPAC - potassium thiocyanate) - crystals that do not have color and odor; In a finely dispersed state they acquire a white color. The substance has a bitterish acute taste, is poisonous. Potassium rodanide dissolves well in many solvents, such as water, amyl alcohol and ethanol.

Receiving

The substance is obtained only chemically, it is extracted from natural sources (blood and human saliva) - extremely costly. In order to synthesize potassium thiocyanate, it is necessary to mix solutions of ammonium thiocyanate and potassium hydroxide (trivial name - caustic potassium).

Experience is conducted under traction, because the ammonia released can cause chemical burns and poisoning; Then, the purified solution is filtered and the residue is evaporated to obtain crystals of the desired substance. When the product is released to seventy percent and a sufficiently pure sample of ammonium thiocyanate, this method is very effective.

Another way is to fuse sulfur with potassium cyanide, but this method of obtaining potassium thiocyanate is very dangerous because of the high toxicity of cyanide.

Application

Potassium thiocyanate, its derivatives and solutions with different concentrations in several industries are used. For example:

• Textile industry.
• A film photograph.
• Organic synthesis.
• Analytical chemistry.

Areas of use

1. In the textile industry. Potassium thiocyanate solution is used for dressing fabrics, for example - silk, during painting and processing in order to preserve the original properties of the material.
2. In organic synthesis. Some organic substances, such as thiourea, synthetic mustard oil and various dyes, are synthesized from potassium thiocyanate. Also with its help, other thiocyanates are obtained, for example, copper thiocyanate-2.
3. In analytical chemistry, a solution of potassium thiocyanate is used to determine cations of ferric iron in matter. An illustrative example is the reaction in which potassium thiocyanate and iron-3 chloride are also involved, also called "blood from water", in which a crimson red hexacyanoferrate 3 of potassium is formed; The trivial name is red blood salt. Also, thiocyanates are used to separate rare metals like thorium and lanthanum. Potassium rodanide and ferric chloride have recently helped in obtaining artificial blood for filming, but this method goes into the background because of the introduction of computer graphics in the film industry.
4. In agriculture, strong insecticides are obtained from solutions of thiocyanates. There are two possible reactions:

• The first is obtaining thiocyan gas by removing potassium from the salt; Rodan is a rather dangerous gas for all living organisms and is rarely used.
• The second is the dissolution of potassium thiocyanate, the collection of cyanobic acid liberated during the hydrolysis, and the oxidation of the obtained substance to the cyanogen. Cyan is not less poisonous, but heavier gas compared to the syringe, and therefore is often used as an insecticide.

Potassium rodanide is a toxic substance whose lethal dose is about 0.9 grams of substance per kilogram of human body weight when administered orally.

Availability

Rodanid potassium can be purchased at any store of chemical reagents, but in small quantities because of the rather high toxicity. The average price of a reagent is four hundred rubles per kilogram, the sale is most often limited to two kilograms in one hand.

Security

Due to its toxicity, potassium thiocyanate must be stored under special conditions for safety requirements when handling poisonous substances:

1. Crystals and solutions of potassium thiocyanate are categorically forbidden to be taken orally, and solutions with a high concentration of the basic substance on the skin are highly undesirable.
2. Despite the fact that the drug is toxic only when used inside, it is desirable to work with the substance in rubber gloves and a lab coat, as well as with all chemical reagents for basic safety requirements.
3. It is necessary to isolate the substance from children and persons who do not have the knowledge of a laboratory assistant, since this can cause unpleasant incidents with the loss of reagents, improper application and sudden death.
4. Since the substance is non-flammable and fairly stable in the air, you can do without storing the substance in the dark. Dry closet. Avoid high humidity and direct sunlight, as the reagent may deteriorate due to decomposition into components. Also according to the NFPA 704 standard, the following symbols are on rhombic marking: 3 0 0 W, where 3 (blue diamond) - toxicity, 0 (red and yellow) - flammability and reactivity, and W - mark for interaction with water, with Which is the release of toxic thiocyanic acid.

And remember, chemical experiments are amazing and unique, but never disregard safety techniques!