A 1.00 g sample of enriched water, a mixture of H2O and D2O, reacted completely with Cl2 to give a mixture of HCl and DCl. The HCl and DCl were then dissolved in pure H2O to make a 1.00 L solution. A 25.00 mL sample of the 1.00 L solution was reacted with excess AgNO3 and 0.3800 g of an AgCl precipitate formed. What was the mass % of D2O in the original sample of enriched water?
Atomic masses (g/mol): H = 1.0, D = 2.0, O = 16.0, Cl = 35.5, Ag = 107.9