Title: Calcium Hydride
CAS Registry Number: 7789-78-8
Molecular Formula: CaH2
Molecular Weight: 42.09
Percent Composition: Ca 95.22%, H 4.79%
Literature 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°. 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.
Melting point: mp 1.86°
Density: d 1.7
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. |