On a cloudy, windy day in August the temperature above Lake Superior reached 25°C The barometer read 760 mmHg, and a scientist aboard an EPA research vessel measured an oxygen concentration (partial pressure) of 0.18. If there is no water vapor in the air, the oxygen partial pressure would have been 0.2. Assuming that nitrogen, oxygen, and water vapor are the only important contributors to the gas pressure, calculate the equilib-rium constant at 25°C for the reaction:
