In modern inorganic chemistry, the classification of s alts, the interaction and properties of elements and their various compounds are of great importance. There are substances that, among others, occupy special places. Such compounds, in particular, should include calcium sulfate. The formula of the substance is CaSO4.
Relatively large deposits of this compound in the earth's crust allow it to be used as a raw material in the production of various materials. The resulting substances can be successfully used in construction, medicine and other fields.
In natural conditions, deposits of a mineral with the composition CaSO4 2 H2O are found. Calcium sulfate is also found in sea (about 1,800,000 tons per cubic meter) and fresh water.
Anhydride CaSO4 is a white powder with a density of 2.90-2.99 grams per cubic centimeter. The compound actively absorbs moisture from the air. Due to this property, calcium sulfate is used as a drying agent.
At a temperature of one thousand four hundred and fifty degrees, the substance melts and decomposes. The solubility of a substance increasesin the presence of HCl, HNO3, NaCl, MgCl2. Calcium sulfate reacts with sulfuric acid and is reduced when sintered with carbon.
Being in water along with MgSO4 and MgCl2, CaSO4 gives it permanent hardness. Chemical softening of the liquid is possible with the help of reagents. Reducing water hardness is based on the introduction of substances enriched with its anions.
Water softening is also carried out by ion exchange. This method is based on the ability of individual artificial and natural ion exchangers - high-molecular compounds - to exchange the radicals that make up their composition for the ions present in the solution. Aluminosilicates (Na2[Al2Si2O8]∙nH2O, for example) often act as ion exchangers.
Hydrate with the composition 2CaSO4 H2O - alabaster (burnt gypsum) - is used in the manufacture of binders. These substances are powdered compounds, from which, when mixed with water, a plastic mass is first formed, and subsequently hardened into a solid mass. Obtaining alabaster is carried out in the process of firing gypsum under the influence of a temperature of one hundred and fifty to one hundred and seventy degrees. This property is used in the production of partition panels and slabs, casts of objects, as well as in the implementation of plaster work.
Roasting under the influence of a temperature of more than two hundred degrees leads to the formation of a soluble form of anhydrous calcium sulfate, at a temperature of more than five hundred degrees - an insoluble form. The latter loses its abilityattach water, therefore it cannot be used as a binder.
Natural gypsum can be used as an initial product in the production of cement and sulfuric acid by a combined method.
Natural calcium sulfate can also be used as a desiccant in the analysis of organic compounds. An anhydrous compound is able to absorb 6.6% of moisture from the entire mass. Calcium sulfate is also used in the production of thermal insulation materials.
