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Calcium in nature

Because of its prevalence in the earth's crust, calciumoccupies the fifth place, its content is 2.96% by mass. It actively migrates, accumulating in various geochemical systems. About 385 calcium minerals are known, by their number it ranks fourth among all the chemical elements. CALCIUM prevails in the lower part of the earth's crust, in the mantle of the Earth it is small. Most of this element is a part of feldspar - anorthite. Calcium also contains: gypsum, marble and limestone, lime is the product of its roasting. In living matter, calcium is the most important of metals, there are organisms containing more than 10% calcium, they build their skeleton from its compounds. Accumulation of limestone is associated with the burials of skeletons of marine plants and animals. Plunging into the depths of the Earth, they are mineralized and transformed into various types of marble. Rivers bring calcium into the ocean, but in water it does not linger, concentrating in the skeletons of organisms. After their death, calcium is deposited on the bottom.

Physical and chemical properties

In calcium, face-centered cubiccrystal cell. This element is very active chemically, in compounds it is bivalent. At room temperature, the metal easily reacts with oxygen and air moisture, for this reason it is stored in sealed closed containers or in mineral oils. When heated in air or in oxygen, it ignites, forming calcium oxide. The reaction with cold water first proceeds quickly, and then slows down due to the formation of a film of calcium hydroxide. This metal reacts vigorously with acids or hot water, releasing hydrogen. With bromine and calcium chloride, a reaction occurs at a temperature above 400 ° C, forming bromide and calcium chloride.

Preparation and application

In the industry, calcium is produced in two ways. In the first case, a briquetted mixture of calcium oxide and aluminum powder is heated to 1200 ° C in vacuum, with calcium vapor deposited on a cold surface. The second method of preparation is the electrolysis of a melt of calcium and potassium chlorides using a liquid copper-calcium cathode. In pure form, calcium is used as a reducing agent for rare earth metals and their compounds. It is used for removal of sulfur from petroleum products, purification of argon from nitrogen impurities, for dehydration of organic liquids, and also in electrovacuum devices as a gas absorber.