Chromium (Chromium, Cr) is a chemical element of group VI periodic table of elements, number 24, atomic weight (mass) 51,9. Solid white shiny metal, temperature melting 1890°, temperature boiling 2480 degrees, the density 7,16. Used in the steel industry to produce high quality steels.
Chrome compounds (oxides and salts of ammonium sulphate) are used in leather industry, electroplating for chrome plating of products, in the manufacture of paints, as prograsses grain in agriculture.
Chrome compounds penetrate the body through the respiratory tract and mucous membranes and intact skin. Most are toxic compounds hexavalent chromium (chromium trioxide, chromic and Dvorakova acid and others). Metallic chromium and trivalent compounds have low toxicity. Chrome compounds with effect on the skin may lead to the development of lesions type of eczema (see), dermatitis (see)Have also irritating and prijigatm action on mucous membranes.
Acute poisoning compounds of chromium is rare. Thus there are the phenomena of acute enteritis, the defeat of the respiratory tract, accompanied by cough with sputum, elevation of body temperature, shortness of breath, cyanosis, moist rales in the lungs. In severe cases can cause nervous system, liver, kidneys (anuria, azotemia), sometimes fatal.
Chronic poisoning are accompanied by headaches, weight loss, diarrhoea events; possible gastritis, peptic ulcer disease, sometimes there are signs of liver damage (toxic jaundice).
Characteristic exposure to chromium compounds is the development of ulcerative lesions of the mucous membranes of the mouth and nose until the perforation cartilaginous part of the nasal septum. At hit of chromium compounds in fresh scratches, cuts, abrasions may develop long-term recurrent ulcers.
Treatment. Care of the mucous membrane of the nose (washing with soap and water), the lubrication of the nasal passages fish oil, a mixture of lanolin with vaseline, yellow mercury ointment, etc.
At hit of chromium compounds in the eye apply copious lavage water (15-20 minutes), fish oil, 30% solution sulfatsila soluble (sulfacetamide sodium). Should eye observation.
Prevention. The effective use of local exhaust ventilation devices, sealing equipment, automation of production processes. In the presence of dust containing chromium, use of respirators type "Petal", hose gas masks, protection of the skin, observance of rules of personal hygiene.
Preliminary and preventive medical examinations (1 every six months) with the participation of otolaryngology and a dermatologist. Maximum permissible concentration of chromium in air of working premises - 0.01 mg/m3 (in terms of CrO3).
Radioactive chromium. Of radioactive isotopes chromium has practical value only Cr51 with a half-life of 27.8 days. This isotope has a very soft x-ray radiation (see) and a small share of gamma radiation (see), due to which it is convenient to be used as a radioactive label, in particular for radioisotope diagnostics (see). In the form of chloride salt Cr51 serves as a label for the plasma of blood and as sodium salt chromate - label for red blood cells. With its help study the total volume of blood plasma volume, the life span of red blood cells and platelets, produce quantitative assessment of blood loss in hidden bleeding. Toxicity Cr51 is low.

Chromium (Chromium), Cr, is a chemical element side VI subgroup of the group of the periodic system of elements of D. I. Mendeleyev. Ever since. room 24, at. mass (ATA. weight) 51,996, valence +6, +3, + 2. The content in the earth crust 0,03 wt.%. Manganese is found in the tissues of plants, animals and humans. The biological role of chromium is not clear.
Chrome is a hard, silvery-white metal, density 7,16, temperature PL 1890°, temperature instrumentation 2480 degrees. Soluble in dilute sulfuric and hydrochloric acids and release of hydrogen.
In the air under normal conditions chrome inert, at high temperature reacts with oxygen, nitrogen, sulfur, and other chemical elements. Oxygen chrome forms an oxide of chromium - CrO (main oxide).
Oxide of chromium - Cr2O3 (chrome green, green kroons), the corresponding hydroxide Cr (OH)3 - amphoteric connection with acids forming salts CrCl3, Cr2 (SO4)3, with alkalis and salts chromic acid - chromites, for example NaCrO2 and other Chromic anhydride CrO3 - acid oxide. The two acids: chrome H2CrO4 and Dvorakova N2Cr2O7, salts of these acids - chromates and bichromate - strong oxidants.
Apply chromium and its compounds in the production of special steels and non-ferrous alloys, chrome metal surfaces for corrosion protection, in the production of paints, catalysts.
Chromic alum is used in the tanning, dyeing, the production of ink, photographic technique and other
The bichromate of potash To2Cr2O7 mixed with concentrated sulfuric acid (chrome mix) used in laboratories for chemical washing of utensils.
Chrome compounds are poisonous.