Question

Under identical conditions, separate samples of O2 and an unknown gas were allowed to effuse through identical membranes simultaneously. After a certain amount of time, it was found that 5.36 mL of O2 had passed through the membrane, but only 3.60 mL of of the unknown gas had passed through. What is the molar mass of the unknown gas?

Answer 1

Let's assume the time is 1 sec. Then rate O2 = 5.36 mL/sec.
rate unknown gas = 3.60 mL/sec
rate O2/rate unk) = sqrt(mm unk/mmO2)
Solve for mm unk.