Calcium Hydride

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.
Calcium Hypochlorite Calcium Hypophosphite Calcium Iodate Calcium Iodide Calcium Iodobehenate

Calcium hydride
Calcium hydride
Identifiers
CAS number 7789-78-8 YesY
PubChem 105052
ChemSpider 94784 YesY
EC number 232-189-2
Jmol-3D images Image 1
Properties
Molecular formula CaH2
Molar mass 42.094 g/mol
Appearance gray powder (white when pure)
Density 1.70 g/cm3, solid
Melting point 816 °C
Solubility in water reacts violently
Solubility reacts in alcohol
Structure
Crystal structure Orthorhombic, oP12
Space group Pnma, No. 62
Hazards[1]
GHS pictograms Water-react. 1
GHS signal word DANGER
GHS hazard statements H260
EU Index 001-004-00-5
EU classification Flammable (F)
R-phrases R15
S-phrases (S2), S7/8, S24/25, S43
Related compounds
Other cations Sodium hydride,
Potassium hydride
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Calcium hydride is the chemical compound with the formula CaH2. This grey powder (white if pure, which is rare) reacts vigorously with water liberating hydrogen gas. CaH2 is thus used as a drying agent, i.e. a desiccant.

CaH2 is a saline hydride, meaning that its structure is salt-like. The alkali metals and the alkaline earth metals all form saline hydrides. A well-known example is sodium hydride, which crystallizes in the NaCl motif. These species are insoluble in all solvents with which they do not react because they have extended structures. CaH2 crystallizes in the PbCl2 (cotunnite) structure.[2]