Q. How to balance Ca(OH)2 HCl → CaCl2 H2O

The balanced equation for this acid-base neutralization reaction is Ca(OH)2 + 2HCl → CaCl2 + 2H2O. To balance this equation, begin by recognizing that calcium hydroxide contains two hydroxide ions (OH-) that will each react with one hydrogen ion (H+) from hydrochloric acid to form water. Start with the skeleton equation and identify that calcium chloride (CaCl2) contains two chlorine atoms, meaning you need two HCl molecules on the reactant side.

Once you place a coefficient of 2 before HCl, count your atoms: you now have one calcium, two chlorines, four hydrogens (two from the 2HCl and two from Ca(OH)2), and two oxygens on the left side. On the right side, you have one calcium and two chlorines in CaCl2, which are already balanced. For water, you need to account for four hydrogen atoms and two oxygen atoms from the reactants, which requires placing a coefficient of 2 before H2O. The final check confirms balance: 1 Ca, 2 Cl, 4 H, and 2 O on each side. This double displacement reaction where a base neutralizes an acid to form a salt and water is one of the most common reaction types in chemistry, and getting the stoichiometry right is essential for laboratory work, titrations, and industrial neutralization processes where you need to know exactly how much acid will neutralize a given amount of base.