A sample of 1.43 g of helium and an unweighed quantity of O2 are mixed in a flask at room temperature. The partial pressure of helium in the flask is 43.0 torr , and the partial pressure of oxygen is 158 torr .
What is the mass of the oxygen in the container?
We're being asked the mass of oxygen in the container filled with a mixture of oxygen and helium.
Recall that the partial pressure of a gas (PGas) in a mixture is given by:
where χGas = mole fraction of the gas and Ptotal = total pressure of the gas mixture.
The mole fraction of the gas is then given by: