A 4. 0-l sample of helium (molar mass = 4. 00 g/mol) was placed in a container fitted with a porous membrane. Half of the helium effused through the membrane in 12 hours. A 4. 0-l sample of oxygen (o2) (molar mass = 32. 00 g/mol) was placed in an identical container. How many hours will it take for half of the oxygen (o2) to effuse through the membrane?.
