Calcium metal reacts with liquid water to produce calcium hydroxidesolution and hydrogen gas Ca (s) + 2 H2O (l) > Ca(OH)2 (l) + H2 (g) Ca(OH)2 + 2HCl --> CaCl2 + 2H2O Solution Calcium metal reacts with liquid water to produce calcium hydroxidesolution and hydrogen gas Ca (s) + 2 H2O (l) > Ca(OH)2 (l) + H2 (g) Ca(OH)2 + 2HCl --> CaCl2 + 2H2O.