Change of State - More Grades 3-5 Science on the Learning Videos Channel

The change of state is most commonly used to describe transitions between solid, liquid, and gaseous states of matter, as well as plasma in rare cases. A phase of a thermodynamic system and the states of matter have uniform physical properties. During a phase transition of a given medium, certain properties of the medium change, often discontinuously, as a result of the change of external conditions, such as temperature, pressure, or others. For example, a liquid may become gas upon heating to the boiling point, resulting in an abrupt change in volume. The measurement of the external conditions at which the transformation occurs is termed the phase transition. Phase transitions commonly occur in nature and are used today in many technologies.

A eutectic transformation, in which a two component single phase liquid is cooled and transforms into two solid phases. The same process, but beginning with a solid instead of a liquid is called a eutectoid transformation.
A metastable to equilibrium phase transformation. A metastable polymorph which forms rapidly due to lower surface energy will transform to an equilibrium phase given sufficient thermal input to overcome and energetic barrier.
A peritectic transformation, in which a two component single phase solid is heated and transforms into a solid phase and a liquid phase.
A spinodal decomposition, in which a single phase is cooled and separates into two different compositions of that same phase.
Transition to a mesophase between solid and liquid, such as one of the "liquid crystal" phases.
The transition between the ferromagnetic and paramagnetic phases of magnetic materials at the Curie point.
The transition between differently ordered, commensurate or incommensurate, magnetic structures, such as in cerium antimonide.
The martensitic transformation which occurs as one of the many phase transformations in carbon steel and stands as a model for displacive phase transformations.
Changes in the crystallographic structure such as between ferrite and austenite of iron.
Order-disorder transitions such as in alpha-titanium aluminides.
The dependence of the adsorption geometry on coverage and temperature, such as for hydrogen on iron (110).
The emergence of superconductivity in certain metals and ceramics when cooled below a critical temperature.
The transition between different molecular structures (polymorphs, allotropes or polyamorphs), especially of solids, such as between an amorphous structure and a crystal structure, between two different crystal structures, or between two amorphous structures.
Quantum condensation of bosonic fluids (Bose–Einstein condensation). The superfluid transition in liquid helium is an example of this.
The breaking of symmetries in the laws of physics during the early history of the universe as its temperature cooled.
Isotope fractionation occurs during a phase transition, the ratio of light to heavy isotopes in the involved molecules changes. When water vapor condenses (an equilibrium fractionation), the heavier water isotopes (18O and 2H) become enriched in the liquid phase while the lighter isotopes (16O and 1H) tend toward the vapor phase

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