# Molecule size of water and oxygen

by Coda
Tags: molecule, oxygen, size, water
 P: 108 The density of water is 1kg/L and that of liquid oxygen is 1.14kg/L. The molecular weights are 18 and 32 respectively. So I reckon the volume of an oxygen molecule is about 32/(18*1.14)=1.56 times that of water. The exact volume of each molecule can be calculated using Avagadro's constant and the above data. If the molecules are assumed spherical, apply a factor of $$\frac{\pi}{3\sqrt 2}$$ for closely packed spheres and you can find out the radius. Can't help with materials for osmosis. Wai Wong