Use the Periodic Table to find molar mass of water. Sodium hydroxide (NaOH) and hydrochloric acid (HCl) react to form sodium chloride (NaCl) and water according to the equation: NaOH + HCl → NaCl + H2O What mass of water forms when 2.75 × 10–4 mol NaOH reacts completely? 2.75 × 10–4 mol NaOH = g H2O