g Nitrogen forms a surprising number of compounds with oxygen. A number of these, often given the collective symbol (for "nitrogen + oxygens") are serious contributors to air pollution. They can often be interconverted, sometimes by reaction with oxygen or ozone () in the air. An atmospheric scientist decides to study the reaction between nitrogen dioxide and oxygen that produces dinitrogen pentoxide. He fills a stainless steel reaction chamber with of nitrogen dioxide gas and of oxygen gas and raises the temperature considerably. At equilibrium he measures the mole fraction of dinitrogen pentoxide to be . Calculate the pressure equilibrium constant for the equilibrium between nitrogen dioxide, oxygen, and dinitrogen pentoxide at the final temperature of the mixture. Round your answer to significant digits.