Why is thermal energy (heat) required to freeze ice into crystals?

Answer 1

Thermal energy is required to freeze ice into crystals because when water freezes, the molecules need to slow down and lose kinetic energy in order to form a solid structure. By removing thermal energy, the molecules move more slowly and come closer together, allowing them to form the ordered crystal structure of ice. This process is known as freezing point depression, where reducing the temperature of water lowers the kinetic energy of the molecules, causing them to lock into a solid lattice structure. Without sufficient thermal energy to drive this process, the molecules would not be able to transition from a liquid to a solid state.