Question

A breathing mixture used by deep-sea divers contains helium, oxygen, and carbon dioxide. What is the partial pressure of oxygen at 101.4kPa if P(He) = 68.7kPa and P(CO2) = 1.4kPa?

Answer 1

Answer is: pressure of oxygen is 31,3 kPa.
The total pressure of an ideal gas mixture is the sum of the partial pressures of the gases in the mixture.
p(mixture) = p(helium) + p(oxygen) + p(carbon dioxide).
p(oxygen) = p(mixture) - (p(helium) + p(carbon dioxide)).
p(oxygen) = 101,4 kPa - (68,7 kPa + 1,4 kPa).
p(oxygen) = 101,4 kPa - 70,1 kPa.
p(oxygen) = 31,3 kPa.