Question

when does phase changes

Answer 1

Phase Changes

There are forces of attraction and repulsion that exist between molecules of all substances. These intermolecular forces allow molecules to pack together in the solid and liquid states.

When a pot of water is placed on a burner, it will soon boil. A phase change is occuring; the liquid water is changing to gaseous water, or steam. On a molecular level, the intermolecular forces between the water molecules are decreasing. The heat is providing enough energy for the water molecules to overcome these attractive forces.