Question

Calculate the partial pressure of O2 (P₀₂, mm Hg) in dry air in Arcata (sea level- assume atmospheric pressure of 760 mm Hg). Arcata air never gets fully dry. Assume 90% humidity at 15°C (saturated water vapor pressure at 15°C=12.8 mm Hg) and calculated the actual partial pressure of O2 in Arcata air.

Answer 1

We will use Dalton's Law of Partial Pressure. It states that " The total pressure by a mixture of gases is equal to the sum of the partial pressures of each of the constituent gases. The partial pressure is defined as the pressure each gas would exert if it alone occupied the volume of the mixture at the same temperature"

Here we are given that:

Total atmospheric pressure at sea level = 760 mmHg

Mole fraction of O2 in dry air = 0.2093

Partial pressure of water vapour in humidified air = 12.8 mmHg

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