How small is a water molecule compared to the volume of liquid water?

[hcchong]

One mole of liquid water occupies a volume of 18 cm3. Imagine that each molecule on the average is at the centre of a small cube. (i) What is the length of the sides of this small cube? (ii) Compare this length with the diameter of a molecule.

 

[Astronuc]

1 gram-mole of water has a mass of approximately 18 g, and since water has a density of approximately 1 g/cm³, it has a volume of cm³. How many molecules are in a mole? Knowing that, one can detemine the volume per molecule. One should be able to find the side length from the volume of a cube.