A flask contains 1.45 moles of N2, 0.659 moles of He. If the total pressure is 775 torr, what is the partial pressure of O2 ?

533.2 torr.

Explanation:

The following data were obtained from the question:

Mole of N₂ = 1.45 moles

Moles the He = 0.659 mole

Total pressure = 775 torr

Partial pressure of N₂ =?

Next, we shall determine the mole fraction of N₂. This can be obtained as follow:

Mole of N₂ = 1.45 moles

Moles the He = 0.659 mole

Total mole = 1.45 + 0.659 = 2.109 moles

Mole fraction of N₂ = Mole of N₂ / total mole

Mole fraction of N₂ = 1.45 / 2.109

Mole fraction of N₂ = 0.688

Gina, we shall determine the partial pressure of N₂. This can be obtained as follow:

Total pressure = 775 torr

Mole fraction of N₂ = 0.688

Partial pressure of N₂ =?

Partial pressure of N₂ = total pressure × mole fraction of N₂

Partial pressure of N₂ = 775 × 0.688

Partial pressure of N₂ = 533.2 torr.

Therefore, the partial pressure of N₂ is 533.2 torr.