FACTOID # 26: Delaware is the latchkey kid capital of America, with 71.8% of households having both parents in the labor force.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
   
 
WHAT'S NEW
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Phase diagram

In physical chemistry, mineralogy, and materials science, a phase diagram is a type of graph used to show the equilibrium conditions between the thermodynamically-distinct phases. In mathematics and physics, a phase diagram also has an alternative meaning, as a synonym for a phase space. Physical chemistry is the application of physics to macroscopic, microscopic, atomic and particulate phenomena in chemical systems[1]within the field of chemistry traditionally using the principles, practices and concepts of thermodynamics, quantum chemistry, statistical mechanics and kinetics. ... Mineralogy is an earth science that involves the chemistry, crystal structure, and physical (including optical) properties of minerals. ... The Materials Science Tetrahedron, which often also includes Characterization at the center Materials science is an interdisciplinary field involving the properties of matter and its applications to various areas of science and engineering. ... In thermodynamics, a thermodynamic system is said to be in thermodynamic equilibrium when it is in thermal equilibrium, mechanical equilibrium, and chemical equilibrium. ... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ... Euclid, Greek mathematician, 3rd century BC, as imagined by by Raphael in this detail from The School of Athens. ... The first few hydrogen atom electron orbitals shown as cross-sections with color-coded probability density Physics (Greek: (phúsis), nature and (phusiké), knowledge of nature) is the branch of science concerned with the discovery and characterization of universal laws which govern matter, energy, space, and time. ... For other senses of this term, see phase space (disambiguation). ...

Contents

Pressure-temperature diagrams

The simplest phase diagrams are pressure-temperature diagrams of a single simple substance, such as water. The axes correspond to the pressure and temperature. The phase diagram shows, in pressure-temperature space, the lines of equilibrium or phase boundaries between the three phases of solid, liquid, and gas. This article describes water from a scientific and technical perspective. ... axes is the plural of both axis and axe, and may thus be: Axe An axe is a tool with a metal blade fastened to a handle at 90 degrees, commonly used to split wood. ... The use of water pressure - the Captain Cook Memorial Jet in Lake Burley Griffin in Canberra, Australia. ... Fig. ... For other uses, see Solid (disambiguation). ... A liquid will usually assume the shape of its container A liquid is one of the main states of matter. ... This article does not cite any references or sources. ...

A typical phase diagram. The dotted line gives the anomalous behaviour of water. The green lines mark the freezing point and the blue line the boiling point, showing how they vary with pressure.
A typical phase diagram. The dotted line gives the anomalous behaviour of water. The green lines mark the freezing point and the blue line the boiling point, showing how they vary with pressure.

The markings on the phase diagram show the points where the free energy is non-analytic. The open spaces, where the free energy is analytic, correspond to the phases. The phases are separated by lines of non-analyticity, where phase transitions occur, which are called phase boundaries. Image File history File links Phase-diag. ... Image File history File links Phase-diag. ... Freezing Point (Chinese: 冰點, bing1 dian3) is a news journal in the Peoples Republic of China which has been the subject of controversy over its criticism of Communist Party officials and the sympathetic ear it lent to a Chinese historian who had criticized official history textbooks. ... The boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid at a given pressure. ... The free energy is a measure of the amount of mechanical (or other) work that can be extracted from a system, and is helpful in engineering applications. ... In mathematics, an analytic function is a function that is locally given by a convergent power series. ... In physics, a phase transition, (or phase change) is the transformation of a thermodynamic system from one phase to another. ...


In the diagram, the phase boundary between liquid and gas does not continue indefinitely. Instead, it terminates at a point on the phase diagram called the critical point. This reflects the fact that, at extremely high temperatures and pressures, the liquid and gaseous phases become indistinguishable, in what is known as a supercritical fluid. In water, the critical point occurs at around 647 K (374 °C or 705 °F) and 22.064 MPa. In chemistry and condensed matter physics, a critical point specifies the conditions (temperature, pressure) at which the liquid state of the matter ceases to exist. ... A supercritical fluid is any substance at a temperature and pressure above its thermodynamic critical point. ... The kelvin (symbol: K) is a unit increment of temperature and is one of the seven SI base units. ... The pascal (symbol: Pa) is the SI derived unit of pressure or stress (also: Youngs modulus and tensile strength). ...


The existence of the liquid-gas critical point reveals a slight ambiguity in our above definitions. When going from the liquid to the gaseous phase, one usually crosses the phase boundary, but it is possible to choose a path that never crosses the boundary by going to the right of the critical point. Thus, the liquid and gaseous phases can blend continuously into each other. However, it is impossible for the solid-liquid phase boundary to end in a critical point in the same way as the liquid-gas boundary, because the solid and liquid phases have different symmetry. Sphere symmetry group o. ...


An interesting thing to note is that the solid-liquid phase boundary in the phase diagram of most substances, such as the one shown above, has a positive slope. This is due to the solid phase having a higher density than the liquid, so that increasing the pressure increases the melting temperature. However, in the phase diagram for water the solid-liquid phase boundary has a negative slope. This reflects the fact that ice has a lower density than water, which is an unusual property for a material. Look up Slope in Wiktionary, the free dictionary. ... In physics, density is mass m per unit volume V. For the common case of a homogeneous substance, it is expressed as: where, in SI units: ρ (rho) is the density of the substance, measured in kg·m-3 m is the mass of the substance, measured in kg V is...


Binary phase diagrams

Other, much more complex types of phase diagrams can be constructed, particularly when more than one pure component is present. In that case concentration becomes an important variable. Phase diagrams with more than two dimensions can be constructed that show the effect of more than two variables on the phase of a substance. Phase diagrams can use other variables in addition to or in place of temperature and pressure and composition, for example the strength of an applied electrical or magnetic field and they can also involve substances that take on more than just three states of matter. In chemistry, concentration is the measure of how much of a given substance there is mixed with another substance. ...

A phase diagram for a binary system displaying a eutectic point.

One type of phase diagram plots temperature against the relative concentrations of two substances in a binary mixture called a binary phase diagram. Such a mixture can be either a solid solution, eutectic or peritectic, among others. These two types of mixtures result in very different graphs. A textbook example of a eutectic phase diagram is that of the olivine (forsterite and fayalite) system. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... His name is Kushal Bhardwaj who has recently dicovered compounds, elements and mixtures. ... Fig. ... A eutectic or eutectic mixture is a mixture of two or more phases at a composition that has the lowest melting point, and where the phases simultaneously crystallise from molten solution at this temperature. ... Peritectic transformations occur when a liquid and solid phase of fixed proportions react at a fixed temperature to yield a single solid phase. ... The mineral olivine (also called chrysolite and, when gem-quality, peridot) is a magnesium iron silicate with the formula (Mg,Fe)2SiO4. ... Forsterite (Mg2SiO4) is the magnesium rich end-member of the olivine solid-solution series. ... Fayalite (Fe2SiO4) is the iron rich end-member of the olivine solid-solution series. ...


In addition to the above mentioned types of phase diagrams, there are thousands of other possible combinations. Some of the major features of phase diagrams include congruent points, where a solid phase transforms directly into a liquid. There is also the peritectoid, a point where two solid phases combine into one solid phase during heating. The inverse of this, when one solid phase transforms into two solid phases during heating, is called the eutectoid.


A complex phase diagram of great technological importance is that of the iron-carbon system for less than 7% carbon (see steel). General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Standard atomic weight 55. ... General Name, Symbol, Number carbon, C, 6 Chemical series nonmetals Group, Period, Block 14, 2, p Appearance black (graphite) colorless (diamond) Standard atomic weight 12. ... The steel cable of a colliery winding tower. ...


The x-axis of such a diagram represents the concentration variable of the mixture. As the mixtures are typically far from dilute and their density as a function of temperature usually unknown the preferred concentration measure is mole fraction. A volume based measure like molarity would be unadvisable. In chemistry, concentration is the measure of how much of a given substance there is mixed with another substance. ... The mole fraction is one way of expressing the relative concentration of a given species. ... This page refers to concentration in the chemical sense. ...


Common components of a phase diagram

Lines of equilibrium or phase boundaries refer to the lines that demarcate where phase transitions occur.


A triple point is, in a pressure-temperature phase diagram, the unique intersection of the lines of equilibrium between three states of matter, usually solid, liquid, and gas. In physics, the triple point of a substance is the temperature and pressure at which three phases (gas, liquid, and solid) of that substance may coexist in thermodynamic equilibrium. ... In thermodynamics, a thermodynamic system is said to be in thermodynamic equilibrium when it is in thermal equilibrium, mechanical equilibrium, and chemical equilibrium. ...


For a phase diagram with temperature on the vertical axis, a solidus is a line below which the substance is stable in the solid state. A liquidus is a line above which the substance is stable in a liquid state. There may be a gap between the solidus and liquidus; within the gap, the substance is replaced by a mixture of solid crystals and liquid. In chemistry, materials science, and physics, the solidus is a line on a phase diagram below which a given substance is stable in the solid phase. ... In chemistry, materials science, and physics, the liquidus is a line on a phase diagram above which a given substance is stable in the liquid phase. ...


Liquid crystal phase diagrams

In liquid crystal physics, phase diagrams are used in the case of mixing of nematogenic compounds to distinguish between the isotropic liquid phase, the nematic liquid phase. Schlieren texture of Liquid Crystal nematic phase Liquid crystals are substances that exhibit a phase of matter that has properties between those of a conventional liquid, and those of a solid crystal. ... Isotropic means independent of direction. Isotropic radiation has the same intensity regardless of the direction of measurement, and an isotropic field exerts the same action regardless of how the test particle is oriented. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...


See also

It has been suggested that this article or section be merged with Gibbs phase rule. ... Hamiltonian mechanics is a re-formulation of classical mechanics that was invented in 1833 by William Rowan Hamilton. ...

External links

Wikimedia Commons has media related to:
Phase diagram
  • A collection of about 150 alloy phase diagrams and some PT diagrams
  • Iron-Iron Carbide Phase Diagram Example
  • How to build a phase diagram
  • Phase Changes: Phase Diagrams: Part 1
  • Equilibrium Fe-C phase diagram

Image File history File links Commons-logo. ... The Wikimedia Commons (also called Wikicommons) is a repository of free content images, sound and other multimedia files. ...


  Results from FactBites:
 
Phase Diagram (549 words)
As the substance is subjected to the temperature and pressure pairs that follow this line the solid and liquid phases to coexist in equilibrium.
As the substance is subjected to the temperature and pressure pairs that follow this line the solid and gas phases to coexist in equilibrium.
As the substance is subjected to the temperature and pressure pairs that follow this line the liquid and gas phases coexist in equilibrium.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m