Potassium thiocyanate - a toxic substance used in analytical chemistry

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

Getting

A substance is obtained only by chemical means; isolating it from natural sources (human blood and saliva) is extremely expensive. In order to synthesize potassium thiocyanate, it is necessary to mix solutions of ammonium thiocyanate and potassium hydroxide (the trivial name is caustic potassium).

The experiment is carried out under traction, because the emitted ammonia can cause chemical burns and poisoning; then the filtered solution is filtered and the residue is evaporated to obtain crystals of the desired substance. With a yield of up to seventy percent and a sufficiently pure sample of ammonium thiocyanate, this method is very effective.

Another method is the fusion of sulfur with potassium cyanide, however, this method of obtaining potassium thiocyanate is very dangerous due to the high toxicity of cyanide.

Application

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

• Textile industry.
• Film photography.
• Organic synthesis.
• Analytical chemistry.

Areas of use

1. In the textile industry. A solution of potassium thiocyanate is used to etch tissues, for example, silk, during dyeing and processing in order to preserve the original properties of the material.
2. In organic synthesis. Some organic substances are synthesized from potassium thiocyanate, such as thiourea, synthetic mustard oil and a variety of dyes. Other thiocyanates, for example, copper-2 rhodanide, are also obtained with its help.
3. In analytical chemistry, a solution of potassium thiocyanate is used to determine ferric cations in a substance. A case in point is a reaction in which potassium thiocyanate and iron-3 chloride, also called “blood from water”, are involved in which a purple-red potassium hexacyanoferrate 3 is formed; the trivial name is red blood salt. Thiocyanates are also used to separate rare metals like thorium and lanthanum. Potassium thiocyanate and jelly chloride have recently been helping to obtain artificial blood for filming, but this method is being relegated to the background due to 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 the production of 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 released during the hydrolysis of hydrocyanic acid and the oxidation of the resulting substance to cyan. Cyan is a no less poisonous, but heavier gas than rhodanum, and therefore is often used as an insecticide.

Potassium thiocyanate is a toxic substance, the lethal dose of which is about 0.9 grams of a substance per kilogram of a person’s weight when given orally.

Availability

Potassium thiocyanate can be bought at any chemical reagent store, but in small quantities due to its fairly high toxicity. The average price of a reagent is four hundred rubles per kilogram; sales are most often limited to two kilograms in one hand.

Security

Due to its toxicity, potassium thiocyanate must be stored in special conditions according to safety requirements when handling toxic substances:

1. Crystals and solutions of potassium thiocyanate are strictly forbidden to take inside and it is extremely undesirable to get solutions with a high concentration of the main substance on the skin.
2. Despite the fact that the drug is toxic only when used internally, it is advisable to work with the substance in rubber gloves and a lab coat, as well as with all chemical reagents according to the basic safety requirements.
3. It is necessary to isolate the substance from children and persons who do not have knowledge of the laboratory assistant, as this can cause unpleasant incidents with the loss of reagents, improper use and sudden death.
4. Since the substance is non-combustible and stable enough in air, you can do with storing the substance in the dark. dry closet. Avoid high humidity and direct sunlight, as reagent spoilage may occur due to its decomposition into its constituent parts. Also, according to the NFPA 704 standard, the following symbols appear on the rhombic marking: 3 0 0 W, where 3 (on the blue rhombus) - toxicity, 0 (on red and yellow) - combustibility and reactivity, and W - mark for interaction with water, when which is the release of toxic thiocyanic acid.

And remember, chemical experiments are amazing and unique, but never neglect safety precautions!