Q. How to balance HNO3 Ca(OH)2 → Ca(NO3)2 H2O

The balanced equation for this acid-base neutralization reaction is 2HNO3 + Ca(OH)2 → Ca(NO3)2 + 2H2O. To balance this equation, start by recognizing that calcium hydroxide contains two hydroxide ions (OH-) that need to react with hydrogen ions from nitric acid to form water. First, notice that the product calcium nitrate has two nitrate groups (NO3)2, meaning you need two nitric acid molecules on the reactant side to provide these groups.

Once you place a coefficient of 2 before HNO3, you have two hydrogen atoms and two nitrate groups on the left, which matches the two nitrate groups in Ca(NO3)2 on the right. Now count the hydrogen and oxygen atoms destined for water: you have two H from the two HNO3 molecules and two OH from Ca(OH)2, giving you a total of four H atoms and two O atoms available to form water. This requires a coefficient of 2 before H2O to balance properly. The final balanced equation shows that two molecules of nitric acid neutralize one molecule of calcium hydroxide to produce one unit of calcium nitrate salt and two molecules of water. This double displacement reaction is common in chemistry labs for neutralizing bases with acids, and the stoichiometric ratio is essential for calculating how much acid is needed to completely neutralize a given amount of base.