Posted by Adam on .
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?
I am confused with how to go about answering this question, if someone could help me it would be greatly appreciated.

oopsChemistry 
DrBob222,
I have deleted the original response and replaced it with the following. Check my thinking.
Cl2 + H2O ==> HOCl + HCl
Cl2 + D2O ==> DOCl + DCl
let x = mass H2O
and y = mass D2O

x + y = 1.00
[x*(molar mass AgCl/molar mass H2O)] + [y*(molar mass AgCl/molar mass D2O)] = 0.3800 x 1000/25
Two equation in two unknowns. Solve for x and y and convert to percent. Check my thinking.