Fuel cells have been proposed for use in cars and for power generation as part of a hydrogen economy. They offer the advantages of higher efficiency and cleaner fuel with insignificant pollutants. The reaction is 2H2 + O2 -> 2H2O Where the oxygen comes from the air (21% O2 and 79% N2). Hydrogen flows into a fuel cell at a rate of 27 gmol/min. Air enters the fuel cell in a separate stream. The air stream flow rate ensures that oxygen is fed at 75% excess required for the stoichiometric reaction. All hydrogen is reacted. Assume that a single stream leaves the fuel cell. Calculate the mole fraction of oxygen in the outlet stream.