Partial Pressures of Gas Mixtures You will need the following conversion for parts B and C: 1 mm of Hg = 13.6 mm of HO Pre-Lab Questions 1. What is meant by the term partial pressure? Partial pressure is the pressure exerted by an individual gas in a mixture. A. Partial Pressures of Oxygen and Nitrogen in Air (use Partial Pressures exercise module for a simulation of this experiment) A.1 Volume of test tube - = 78.0 mL A.2 Volume of nitrogen = 62.0 mL A.3 Atmospheric pressure = 754 mm Hg Calculations: A.4 Volume of oxygen = 22.0 mL A 5 Percent oxygen (show calculation)- 22%