A 15% (w/w) solution of BaCl2 in water has a density of 1.12 g/mL. What is the concentration of the same solution expressed as molarity? How many moles of chloride ions are in 25.0 mL of the BaCl2 solution? Solution Molarity = (% w/w x d x 10 / MW) Molarity = (15 x 1.12 x 10 / 208.23) Molarity = 0.807 M moles = Molarity x V in L moles = 0.807 x 25/1000 moles = 0.0202.