A sample of 9.49 g of solid calcium hydroxide is added to 30.0 mL of 0.490 M aqueous hydrochloric acid. Write the balanced chemical equation for the reaction. Physical states are optional.

Ca (OH) 2 (s) + 2HCl (aq) → CaCl2 (aq) + 2H2O (l)

Explanation:

Step 1: Data given

Mass of Ca (OH) 2 = 9.49 grams

Volume of a 0.490 M HCl solution = 30.0 mL = 0.030 L

Step 2: The unbalanced equation

Ca (OH) 2 + HCl → CaCl2 + H2O

On the left side we have 2x O (in Ca (OH) 2) and on the right side we have 1x O (in H2O). To balance the amount of O we have to multiply H2O, on the right side, by 2.

Ca (OH) 2 + HCl → CaCl2 + 2H2O

On the right side we have 4x H (in 2H2O), and on the left side we have 3x H (2x in Ca (OH) 2 and 1x in HCl). To multiply the amount of H, we have to multiply HCl on the left side by 2.

Ca (OH) 2 (s) + 2HCl (aq) → CaCl2 (aq) + 2H2O (l)