Critical line (thermodynamics)
Encyclopedia
In thermodynamics
, a critical line is the higher-dimensional equivalent of a critical point
. It is the
locus of contiguous critical points in a phase diagram
. These lines cannot occur for
a single substance due to the phase rule
, but they can be observed in systems with more variables, such as mixtures. Two critical lines may meet and terminate in a tricritical point
.
Thermodynamics
Thermodynamics is a physical science that studies the effects on material bodies, and on radiation in regions of space, of transfer of heat and of work done on or by the bodies or radiation...
, a critical line is the higher-dimensional equivalent of a critical point
Critical point (thermodynamics)
In physical chemistry, thermodynamics, chemistry and condensed matter physics, a critical point, also called a critical state, specifies the conditions at which a phase boundary ceases to exist...
. It is the
locus of contiguous critical points in a phase diagram
Phase diagram
A phase diagram in physical chemistry, engineering, mineralogy, and materials science is a type of chart used to show conditions at which thermodynamically distinct phases can occur at equilibrium...
. These lines cannot occur for
a single substance due to the phase rule
Gibbs' phase rule
Gibbs' phase rule was proposed by Josiah Willard Gibbs in the 1870s as the equalityF\;=\;C\;-\;P\;+\;2where P is the number of phases in thermodynamic equilibrium with each other and C is the number of components. Typical phases are solids, liquids and gases. A system involving one pure chemical...
, but they can be observed in systems with more variables, such as mixtures. Two critical lines may meet and terminate in a tricritical point
Tricritical point
In condensed matter physics, dealing with the macroscopic physical properties of matter, a tricritical point is a point in the phase diagram of a system at whichthree-phase coexistence terminates...
.