Ca(s) + 2H2O(l) → Ca(OH)2(aq) + H2(g)
Calcium metal and water react to produce calcium hydroxide and hydrogen gas.
Calcium reacts vigorously and exothermically with cold water, but not as vigorously as the elements in Group 1 (sodium, potassium, francium, lithium, rubidium, and cesium). Bubbles of hydrogen gas are given off, and a white precipitate of calcium hydroxide is formed, together with an alkaline solution. Calcium hydroxide is slightly soluble in water. Once the solution is saturated, it becomes milky as solid calcium hydroxide appear.
