Calcium nitrate

Calcium nitrate has the molecular formula of Ca(NO3)2 and the molecular weight of 164.0935 g/mol. Its CAS number is 10124-37-5. Calcium nitrate may be prepared by the reaction of nitric acid with calcium carbonate or calcium sulfide:
CaCO3 + 2HNO3 Ca(NO3)2 + CO +H2O
CaS + 2HNO3 Ca(NO3)2 +H2S
It is very soluble and forms a tetrahydrate, Ca(NO3) 2·4H2O if the solution is evaporated to dryness. The CAS number of the anhydrate is 10124-37-5 while that of the tetrahydrate is 13477-34-4. As with the beryllium nitrate salts, variation of the nitric acid concentration affects the type of hydrate produced. The trihydrate is known (CAS number 10124-37-5) but not the monohydrate. The anhydrate is a white cubic crystal that is hygroscopic; its density is 2.504 g/cm3 and it melts at 561°C. This salt is highly soluble in water and also dissolves in alcohols and acetone. The tetrahydrate melts in its own waters of hydration at 42.7°C and loses 4H2O molecules at 132°C. It decomposes to form nitrogen oxides and CaO similar to the behavior of the other alkaline earth nitrates. The anhydrous salt is soluble at 121.2 g/100 ml at 20°C and 271.2 g/100 ml at 40°C.