Density of solids, liquids and gases

The difference between the densities of solids, liquids and gases is due to the distance between the particles in each state of matter.

The particles of a solid are very close together.

It melts when it changes from the solid state to the liquid state.

The particles remain close together, so there is usually only a small increase of .

The same mass of liquid will have slightly greater volume than the solid.

As density equals \(\frac{\text{mass}}{\text{volume}}\), the liquid will have slightly lower density.

The density of solid iron = 7.8 g/cm³

The density of liquid iron = 6.9 g/cm³

A substance evaporates when it changes from the liquid state to the gas state.

Its particles move freely and are very far apart, so there is a large increase of volume.

The same of gas will have very much greater volume than the liquid, and so will have much lower density.

The density of liquid oxygen = 1.1 g/cm³

The density of gaseous oxygen = 0.0014 g/cm³

State	Distance between particles	Density	Density in g/cm³
Solid	Very close together	High	Solid iron = 7.8
Liquid	Slightly further apart than a solid	Slightly less than the solid	Liquid iron = 6.9
Gas	Very much further apart than a solid or liquid	Very much less than the solid or liquid	Oxygen gas = 0.0014

State	Liquid
Distance between particles	Slightly further apart than a solid
Density	Slightly less than the solid
Density in g/cm³	Liquid iron = 6.9

State	Gas
Distance between particles	Very much further apart than a solid or liquid
Density	Very much less than the solid or liquid
Density in g/cm³	Oxygen gas = 0.0014

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