Why are freezing, condensation and deposition exothermic processes?

1 Answer
Feb 26, 2017

Because all of these slow molecular motion, i.e. require the extraction of heat from the system.


Exothermic by definition means the release of heat from a system. Any process that slows down the particles in the system due to heat flow outwards is therefore exothermic.

  • Freezing has particles of a liquid slow down to form a lattice structure and become a solid phase.
  • Condensation has particles of a gas slow down to form intermolecular forces and transition into a liquid phase.
  • Deposition has particles of a gas slow down to form a lattice structure, becoming a solid and skipping the liquid phase.

Thus, the above three processes are exothermic with respect to the system.