Question

The atmosphere is about 21% oxygen. At a pressure of 749 torr, what is the partial pressure of O2?

Answer 1

Answer:

157.29 Torr

Explanation:

This question may be solved by the mole fraction.

Mole fraction → Moles of gas / Total moles = Partial pressure of gas / Total pressure

If the atmosphere is about 21% you assume that the mole fraction is 0.21 so:

0.21 = Partial pressure of gas / Total pressure

0.21 = Partial pressure of gas / 749 Torr

Partial pressure of the gas = 749 Torr . 0.21 →  157.29 Torr