Example

Question:

What is the average distance between atoms (interatomic distance) in water? Use the data given in Examples 12.1 and 12.2.

Solution:

A given mass of water in vapour state has \(1.67 \times 10^3\) times the volume of the same mass of water in liquid state (Ex. 12.1). This is also the increase in volume available for each molecule of water.
When volume increases by \(10^3\) times, the radius increases by \(V^{1/3} = 10\) times, so radius becomes \(10 \times 2\,\text{Å} = 20\,\text{Å}\) (from Example 12.2).
So, the average distance is \(2 \times 20 = 40\,\text{Å}\).