Q. What are the products of the following reaction: CaH2(s) 2H2O(l) →

The products of the reaction CaH2(s) + 2H2O(l) → are calcium hydroxide (Ca(OH)2) and hydrogen gas (H2), giving the complete balanced equation: CaH2(s) + 2H2O(l) → Ca(OH)2(aq) + 2H2(g). Calcium hydride, a white crystalline solid, reacts vigorously with water in what's classified as a hydrolysis reaction (literally "breakdown by water"). In this reaction, the hydride ions (H-) from calcium hydride act as strong bases, pulling protons from water molecules to form hydrogen gas, while the calcium ions combine with hydroxide ions from water to produce calcium hydroxide.

This reaction is notably vigorous and highly exothermic, producing flammable hydrogen gas rapidly, which creates a serious fire hazard if ignition sources are nearby. Calcium hydride is used as a drying agent in organic chemistry laboratories precisely because it reacts so readily with water, and it's also used as a portable source of hydrogen gas in situations where storing H2 gas cylinders is impractical. The reaction must be conducted with proper safety precautions—adequate ventilation, no open flames, and protective equipment—because the rapid generation of hydrogen gas can cause pressure buildup in closed containers and the alkaline calcium hydroxide solution produced is corrosive. The stoichiometry shows that one mole of CaH2 produces two moles of H2, making it an efficient hydrogen source by weight, which is why calcium hydride has been explored for hydrogen storage applications despite the challenges of handling this reactive material.