CO2 diffuses more easily through the respiratory membrane than O2 because it is
Less dense
More soluble in plasma
Less molecular weight
Less PCO2 in the alveoli
Diffusion of Gases Through Liquids The more soluble a gas is, the faster it will diffuse. In this case carbon dioxide diffuses much faster than oxygen, as it is much more soluble. Ref: guyton and hall textbook of medical physiology 12 edition page number:348,349,350
Respiratory system