Calcium in nature
In its prevalence in the crust of calcium ranked fifth, its content is 2.96% by weight.He actively migrate, accumulate in various geochemical systems.There are about 385 minerals calcium, according to their number, he ranked fourth among all chemical elements.
Calcium prevails in the lower crust, into the mantle it a little.Most of this element is part of the feldspar - anorthite.Calcium also include gypsum, marble, limestone, lime is a product of his firing.
calcium in living matter - the most important of the metals, there organisms containing more than 10% of calcium, they build a skeleton of its compounds.The accumulation of limestone associated with the disposal of skeletons of marine plants and animals.Plunging into the depths of the earth, they are mineralized and turn into different types of marble.Rivers
bring calcium into the ocean, but in the water it is not delayed, concentrating in the skeletons of organisms.After their death of calcium deposits on the bottom.
Physical and chemical properties
calcium have a face-centered cubic crystal lattice.This element is very active chemically, in the compounds it is bivalent.At room temperature, the metal readily reacts with oxygen and moisture in the air, for this reason, it is stored in a sealed vessel or in mineral oils.When heated in air or oxygen, it is ignited, forming calcium oxide.
reaction with cold water first flows quickly and then slows down because the film forming calcium hydroxide.The metal reacts vigorously with an acid or hot water, releasing hydrogen.With bromine and chlorine and calcium enters the reaction at a temperature above 400 ° C, to form bromide and calcium chloride.
Preparation and use
In industry calcium is obtained in two ways.In the first case is heated to 1200 ° C in vacuo to briquette a mixture of calcium oxide and aluminum powder, and the vapor deposited calcium on a cold surface.A second method to obtain a melt electrolysis of chlorides of calcium and potassium in liquid copper and the calcium cathode.
Pure calcium is used as a reducing agent of rare earth metals and their compounds.It is used to remove sulfur from petroleum, argon purification from impurities nitrogen for dewatering organic liquids, as well as other electronic devices as a scavenger gas.
- HiMiK.ru, Calcium