<span>Ca(OH)2 + 2 HCl = 2 H2 O + CaCl2 </span> We are given the amount of hydrochloric acid to be used in the reaction. This will be the starting point for the calculations.
0.124 mol HCl / L soln ( .0375 L solution) ( 1 mol Ca(OH)2 / 2 mol HCl) / 0.020 L Ca(OH)2 solution = 0.12 mol / L Ca(OH)2 = 0.12 M