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