Nomenclature
CAS number: 7789-78-8
CaH
2; mol wt 42.09.
Ca 95.22%, H 4.79%.
Description and references
Prepd by direct combination of calcium and
hydrogen at 300-400°: GB 597055 (1948);
by reduction of lime with magnesium in the presence of hydrogen:
Gibb, Trans. Electrochem. Soc. 93, 198-211 (1948); from CaCl2 and hydrogen
in the presence of sodium: Wade, Alexander, US 2702740 (1955 to Metal Hydrides). Reviews: Halls, Ind. Chem. 22, 680 (1946); Kilb, USAEC APEX-485, 57 pp (1959).
Properties
Orthorhombic crystals or powder; the commercial
product is gray. d 1.7. mp 1.86°. Dangerous when wet. Decomposes with water,
lower alcohols and carboxylic acids to form hydrogen; moderately powerful
condensing agent with ketones and acid esters; more powerful reducing
agent toward metal oxides than lithium or sodium hydrides.Use
To prepare rare metals by reduction of their oxides;
as a drying agent for liquids and gases; to generate hydrogen: 1
g of calcium hydride in water liberates 1 liter of hydrogen at STP;
in organic syntheses.