Calcium Carbonate

Calcium Carbonate CAS: 7440-70-2 Ca HSN: 2836

Alkaline- earth element of atomic number 20, group IIA of the periodic system. Aw 40.08. Valence 2. Six stable isotopes.

Properties: Moderately soft, silver-white, crystal- line metal, oxidizes in air to form adherent pro- tective film, can be machined, extruded, or drawn. Soluble in acid. Decomposes water to liberate hydrogen. D 1.57; mp 845C; sublimes above mp in vacuum; bp 1480C; Brinell hardness 17.

Derivation: Electrolysis of fused calcium chloride, by thermal process under high vacuum from lime reduced with aluminum. Does not occur free in nature.

Forms: Crowns, nodules, ingots, crystals up to 99.9% pure.

Hazard: Evolves hydrogen with moisture. Flam- mable in finely divided state. Fire and explosion

hazard when heated or on contact with strong oxidizing agents.

Use: Alloying agent for aluminum, copper and lead; reducing agent for beryllium; deoxidizer for alloys. Dehydrating oils. Decarburizaton and desulfurization of iron and its alloys, getter in vacuum tubes. Separation of nitrogen from ar- gon. Reducing agent in preparation of chromium metal powder, thorium, zirconium, and uranium. Fertilizer ingredient.

Note: Calcium is an essential component of bones, teeth, shells, and plant structures. It occurs in milk in trace amounts and is necessary in animal and human nutrition. Vitamin D aids in the de- position of calcium in bones.