Description
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Calcium is an alkaline earth metal that is a silvery white solid in its natural state. Calcium readily reacts with water and it forms a layer of oxide and nitride coating if it is exposed to the air. Calcium has an atomic weight of 40.078, a melting point of 1548 °F, and a boiling point of 2703 °F. Some common uses of calcium include: in the formation of quicklime, limestone, and slaked lime, as an ingredient in Portland cement, in calcium chloride for ice removal on roads, as an ingredient in vitamins and food additives, and as an ingredient in fertilizers.
Isolation
Calcium is not found in its pure form in nature, and there are two main processes that are used to isolate calcium.
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Calcium in the form of sedentary rock can be found in such minerals as calcite, dolomite, and gypsum. The most frequently used calcium isolation method for industrial purposes uses electrolysis. During this process, calcium chloride is produced by reacting hydrochloric acid with calcium carbonate. The results of this reaction include calcium chloride, water, and carbon dioxide. The liquid calcium chloride is then subject to electrolysis; the cathode calcium is separated from the anode chloride.
There are two processes that can be used to isolate a small amount of calcium. The first process uses the reducing reaction between lime, (CaO), and aluminum; the results of this reaction include pure calcium and Ca3Al2O6. The second isolation process uses the reducing reaction between calcium chloride with metal sodium; the end result of this reaction is pure calcium and sodium chloride. These processes are not frequently used as pure calcium that has been isolated for industrial purposes is easily obtained commercially.