Gaseous effusion can be used to separate isotopes. Suppose you had a balloon filled with equal molar amounts
of hydrogen, H2, and deuterium, D2, gas. After 10 hours you find that 20.0 % of the hydrogen, H2, had effused
out of the balloon along with some unknown amount of the deuterium, D2.
What would be the molar percentage of D2 gas in the balloon after this 10 hour period?
(Atomic Masses: H 1.01 grams/mol; D 2.01 grams/mol)

Question

Gaseous effusion can be used to separate isotopes. Suppose you had a balloon filled with equal molar amounts
of hydrogen, H2, and deuterium, D2, gas.  After 10 hours you find that 20.0 % of the hydrogen, H2, had effused
out of the balloon along with some unknown amount of the deuterium, D2.   
What would be the molar percentage of D2 gas in the balloon after this 10 hour period?
(Atomic Masses:         H   1.01 grams/mol;     D  2.01 grams/mol)