Cadmium is a silver-white metallic luster, melting point 320.9 deg.] C, a boiling point of 765 deg.] C, a relative density of 8.642. Resilience and ductility. Cadmium slowly oxidizes in humid air and loses its metallic luster, which forms a brown oxide layer on heating. At high temperatures, cadmium reacts with halogen to form cadmium halide [1]. It can also be directly combined with sulfur to form cadmium sulfide. Cadmium is soluble in acid but insoluble in alkali. The oxidation state of cadmium is +1, +2. Cadmium oxide and cadmium hydroxide have very low solubility, they are soluble in acid, but insoluble in alkali. Cadmium can form a variety of complex ions, such as Cd (NH 3 ), Cd (CN), CdCl and the like. Cadmium is highly toxic, and air and food contaminated with cadmium are seriously harmful to humans. In Japan, cadmium poisoning has been "painful."
Various methods are available from a dust containing cadmium or cadmium residue (such as coal or charcoal, or reduction of leaching zinc powder and sulfuric acid substitutions) obtained cadmium. Further purification can be carried out by electrolytic refining and vacuum distillation. Cadmium is mainly used for electroplating of steel, iron , copper , brass and other metals, and has strong corrosion resistance to alkaline substances. Cadmium can be used to make batteries that are small in size and large in capacity. Cadmium compounds are also used in large quantities for the production of pigments and phosphors. Cadmium sulfide, cadmium selenide, and cadmium telluride are used in the manufacture of photovoltaic cells.
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