Movement of Gases across the Lung (PK4)

Question 1

Graham’s law

Answer 1

Diffusion in gaseous state α 1/√MW

Question 2

Henry’s law

Answer 2

Conc. of dissolved gas = partial pressure x solubility coefficient

Question 3

Solubility coefficients of O2 and CO2, and what that means about their relative diffusion speeds in liquids

Answer 3

• O2 = 0.23 ml L-1 kPa-1
• CO2 = 5.30 ml L-1 kPa-1
• Therefore CO2 is 23x more soluble, so diffuses 23x faster

Question 4

How is overall diffusibility of a gas in gas and liquid calculated?

Answer 4

• Combine Graham’s + Henry’s laws
• Diffusibility ratio in air x Diffusibility ratio in liquid