Dry air consists of 78.1% nitrogen (28 g/mol), 20.9% oxygen (32 g/mol), 0.9% argon (40 g/mol), 0.03% carbon dioxide (44 g/mol), and 0.07% other gases by volume. What is the partial pressure of oxygen in air when the total pressure is 760 torr?

Question

Quizplus · Accepted Answer

First, we need to find the mole fraction of oxygen in dry air:
Mole fraction of oxygen = (20.9/100) / (78.1/100 + 20.9/100 + 0.9/100 + 0.03/100 + 0.07/100)
Mole fraction of oxygen = 0.209 / 0.999 = 0.2093

Next, we can use the mole fraction to find the partial pressure of oxygen:
Partial pressure of oxygen = Mole fraction of oxygen × Total pressure
Partial pressure of oxygen = 0.2093 × 760 torr
Partial pressure of oxygen ≈ 159 torr

Therefore, the answer is B.

Dry Air Consists of 78