Question

A 150.0 mL gas tank contains 51.2 g of oxygen gas and 32.6 g helium gas. What is the total pressure in the tank? What is the partial pressure of oxygen?

Answer 1

V = 150 ml = 0.15 L

moles of O2 = 51.2 / 32 = 1.6

moles of He = 32.6 /4 = 8.15

total moles = 1.6 + 8.15 = 9.75

mole fraction of O2 = moles of O2 / total moles

                               = 1.6 / 9.75

                               = 0.164

P V = n R T

P x 0.150 = 9.75 x 0.0821 x 298

P = 1590.28 atm

total pressure = 1590.28 atm

partial pressure of O2 = mole fraction of O2 x total pressure

                                     = 0.164 x 1590.28

                                      = 260.8 atm