Question

The atmospheric pressure is 1.0 atm and Henry’s law constant for O2 is 1.66 x 10^−6 M/mm Hg at 25 °C. Assume air contains 21% oxygen. Calculate the partial pressure of oxygen. (21% of air is oxygen and the mole fraction of O2 is 0.21).

(a) 180 mm Hg

(b) 130 mm Hg

(c) 120 mm Hg

(d) 160 mm Hg

This question was posed to me in an interview for internship.

My question comes from Estimating Oxygen Solubility topic in section Mass Transfer of Bioprocess Engineering

Answer 1

Correct answer is (d) 160 mm Hg

Easiest explanation: The partial pressure of oxygen is:

P (O2) = (1.0 atm) ((760 mm Hg)/(1 atm)) (0.21) = 160 mm Hg.