A 0.2527-g sample of a mixture of Mg(OH)2 and Al(OH)3 was treated with 50.00 mL of 0.225 mol L^-1 HCl(aq). The resulting solution required 13.73 mL of 0.176 mol L^-1 NaOH(aq) to neutralize the excess, unreacted HCl. What was the percentage by mass of Mg(OH)2 in the original sample? When Mg(OH)2 or Al(OH)3 reacts with HCl(aq), the products are a chloride and water.