For Most Substances, Describe The Relative Densities Of The Phases

The density of a substance, or the mass per unit of volume, is a key physical property when describing the different states or ‘phases’ of a substance. Different substances are composed of different molecules and atoms, and these molecules and atoms will interact differently under different conditions; this causes the density of a substance to change depending on the phase. Generally, as the temperature of a substance increases, its molecules and atoms will become less orderly, less dense, and hence less dense than in their solid or liquid states.

In solid phases, the density is highest due to the orderly arrangement of molecules, and the tight bonds between atoms. This arrangement provides it with the highest possible number of molecules per unit volume. This arrangement of atoms also resists any change in its volume, even when pressure or temperature is applied to it.

In liquid phases, the molecules of a substance are spread out, due to the weakening of intermolecular bonds. As a result, the density of the liquid will be lower than in its solid state. This is why it appears to ‘flow’ as it is moved around. The density of a liquid also depends on its temperature; as the temperature increases, its molecules move faster, and the density decreases.

In gas phases, due to the very low density and low viscosity, the molecules of a substance move freely and rapidly, and their ordering is no longer present. This means that the density of a gas is lower than in both solid and liquid phases. Again, the density of a gas can also differ depending on its temperature and pressure.

In conclusion, the density of a substance can change depending on its phase, or state. Generally, the densest phase is the solid phase, followed by the liquid phase, and then the gaseous phase. The density of a phase can also vary depending on its temperature and pressure.