Potassium dichromate
The potassium dichromate substance has severalnames, which, to a greater or lesser extent, frequencies, are used depending on the sphere of use of the substance itself. Traditionally, the chemical theory most often uses the names of potassium dichromate or potassium chromium. When it comes to industrial use, then this compound is designated by the term chromepic. It is very important to understand what kind of connection is involved, because in everyday use, chrome is also called sodium dichromate with the formula Na2Cr2O7 * 2H2O. The chemical formula of potassium cadmium is K2Cr2O7.
Physical properties of potassium cadmium are as follows. Outwardly, this substance is an orange-colored crystal whose crystal lattice is variable under the influence of temperature. At its value up to 257 ° C, the lattice is in the form of triclinic single crystals, and when the temperature is raised above 257 ° C, it changes to monoclinic.
The potassium dichromate substance has a temperaturemelting at 396 ° C, when it rises above 500 ° C, the substance decomposes into K2CrO4, Cr2O3, and oxygen. The specific density of potassium cadmium is 2.69 g / cm3. Potassium dichromate is readily soluble in aqueous solutions:
- at a temperature of 0 ° C, 4.6 grams of potassium chrome is completely dissolved in 100 grams of water;
- at a temperature of 25 ° C, in the same amount of water you can completely dissolve 15.1 grams, and when the temperature is raised to 50 ° C - already 37.7 grams.
In alcohols, for example, in ethanol, potassium dichromate dissolves weakly.
Two-potassium potassium forms a eutectic -a composite liquid solution that crystallizes at the lowest temperature for a given group of substances, the structural-composition formula of which is H2O-K2Cr2O7 with a chrome content of 4.30% by weight. The melting point of this compound is only 0.63 ° C, and it boils at 104.8 ° C (the content of potassium chloride in the solution is 52% by mass).
With the participation of such a substance as potassium dichromate,the reactions take place in acid media if it is represented by an aqueous solution. The substance itself is also the strongest oxidizer, for example, during the reaction of potassium and potassium chromium, a salt of K2SO4 and chromium oxide is obtained.
When reacting with sulfuric and nitric acidspotassium dichromate forms polychromates. When heating mixtures containing this compound and hydrogen peroxide, easily explosive peroxide crystals are obtained, which in turn is an important component of explosives.
Industrially, the production of potassium chrome is carried out by the reaction of Na2Cr2O7 exchange with KCl, at which the solution warms up to enormous temperatures - on the order of 1000-1300 ° C.
Used potassium dichromate, chemical propertieswhich is described above, in the production of various dyes, in the textile and leather industries it is used in the tanning of leather. It is widely used in woodworking and production of matches, making pyrotechnic mixtures, photography. If you dissolve potassium chromium in sulfuric acid, you get a very effective solution for washing glass instruments in laboratories. As a component of potassium chromium is used in dry electrolytes, as well as in metallurgy as an inhibitor of the rusting of metals and their alloys.
Hrompik potassium is an extremely toxic compound. Drops of its solution, reaching the open areas of the human body, destroy the skin. Even small concentrations of this substance can cause serious damage to the respiratory tract and damage the cartilage ligament tissues. Known cases of damage to the kidneys, liver and gastrointestinal tract. Therefore, when carrying out work with potassium dichromate, strict precautions should be taken. Especially care should be taken to protect the respiratory system and skin.
