Question #ee192

1 Answer
Oct 18, 2016

It's really an assumption, but the solid ice and liquid water. Try as you may, they require large pressures applied in order to change the volume by even a little bit.

In other words, they are negligibly compressible at low applied pressures.

Ice is naturally rigid and quite incompressible, while liquid water takes the shape of its container but is not rigid (so it can be morphed but is similarly fairly incompressible).

On the other hand, water vapor is already high in kinetic energy, so moving water molecules in their vapor phase is easy, requiring little changes in pressure.