To solve this problem. use the formula m1 v1 = m2 v2 where m1 is the molarity of the stock soln v1 is the volume of the stock soln m2 is the molarity of the new soln v2 is the volume of the new soln
m1 v1 = m2 v2 13.5(v2) = (10.5)(1.8) v2 = (10.5)(1.8) / 13.5 v2 =1.4 L is needed from the 13.5 M HCl stock soln