Phase changes

Phase changes or phase transitions are events that disrupt the thermodynamic equilibrium of a substance or system. This disturbance causes a change in the phase of the substance. During this change, a jump occurs, during which the physical quantities that characterize the given substance can change.

Melting and solidifying
Atoms, molecules or ions fixed in a crystal lattice vibrate as a result of thermal motion. As the temperature increases, their kinetic energy rises until it reaches such a value that the particles leave the lattice and it disintegrates. The opposite happens when the liquid is cooled.

Evaporation and condensation

 * In a closed container there is a liquid and above it at any temperature its own vapors. If the movement of molecules from the liquid to the gas phase predominates, evaporation occurs and the pressure of the gas above the liquid increases until there are equal numbers of molecules in both the gas and liquid phases (&thinsp;=&thinsp;nasycená pára).
 * If evaporation occurs in the entire volume of liquid, it is a boil'.
 * Sudden cooling of the steam causes its condensation, but condensation centers (small dust particles or ions) are needed for this.

Sublimation and Desublimation
Transition from solid phase' to 'gaseous phase and vice versa.

Ionization and recombination
Transitions from the gas phase to the plasma phase and vice versa.

Related articles

 * Latent heat