Фазни дијаграм — разлика између измена
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Дијаграм на српском ознака: уређивање извора (2017) |
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[[Датотека:Phase-diagram-of-water-serbian.jpg|мини|300px|Фазни дијаграм воде]]
'''Фазни дијаграм''' је помоћно средство у [[Хемија|хемији]], [[Физика|физици]], а посебно у [[Наука о материјалима|науци о материјалима]] и [[Металургија|металургији]] за шематски дводимензионални или мултидимензионални приказ распореда и међусобног односа [[Фаза (термодинамика)|фаза]] једног мултикомпонентног [[систем]]а (течног или чврстог раствора две или више супстанци). Област термодинамике која се бави изучавањем понашања вишекомпонентних система у зависности од притиска, температуре и састава назива се: [[хетерогене равнотеже]].
== Преглед ==
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Common components of a phase diagram are ''lines of equilibrium'' or ''phase boundaries'', which refer to lines that mark conditions under which multiple phases can coexist at equilibrium. Phase transitions occur along lines of equilibrium.
[[Triple point]]s are points on phase diagrams where lines of equilibrium intersect. Triple points mark conditions at which three different phases can coexist. For example, the water phase diagram has a triple point corresponding to the single temperature and pressure at which solid, liquid, and gaseous water can coexist in a stable equilibrium ({{val|273.16|ul=K}} and a partial vapor pressure of {{val|611.657|ul=Pa}}).
The [[solidus (chemistry)|solidus]] is the temperature below which the substance is stable in the solid state. The [[liquidus]] is the temperature 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 consists of a mixture of crystals and liquid (like a "[[slurry]]").<ref>{{cite book |last=Predel |first=Bruno |last2=Hoch |first2=Michael J. R. |last3=Pool |first3=Monte |year=2004 |title=Phase Diagrams and Heterogeneous Equilibria: A Practical Introduction |publisher=[[Springer (publisher)|Springer]] |isbn=978-3-540-14011-5}}</ref>
[[Working fluids]] are often categorized on the basis of the shape of their phase diagram.
== Генерална подела ==
Постоји много подела [[Фазни дијаграм|фазних дијаграма]], једна од најопштијих је она на равнотежне и неравнотежне фазне дијаграме. Ако је систем у равнотежи, односно ако су све [[Фазна трансформација|фазне трансформације]] у еквилибријуму (равнотежи), онда говоримо о тзв. [[Равнотежни фазни дијаграм|равнотежном фазном дијаграму]]. Да би се постигла истинска равнотежа, систему је у принципу потребно бесконачно [[време]]. Како је бесмислено чекати да се постигну апсолутне равнотеже фаза у систему, при мерењу тачака на [[Фазни дијаграм|фазном дијаграму]] најчешће се користе разумна времена која дозвољавају, са једне стране смисаоност поступка, а са друге стране приближавање равнотежном стању.
== Типови ==
=== Дводимензиони дијаграми ===
[[Датотека:Phase-diag2.svg|thumb|310x310px|A typical phase diagram. The solid green line applies to most substances; the dotted green line gives [[Water (molecule)#Density of water and ice|the anomalous behavior of water]]. The green lines mark the [[freezing point]] and the blue line the [[boiling point]], showing how they vary with pressure.]]The simplest phase diagrams are pressure–temperature diagrams of a single simple substance, such as [[water (molecule)|water]]. The [[Cartesian coordinate system|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]].
The curves on the phase diagram show the points where the free energy (and other derived properties) becomes non-analytic: their derivatives with respect to the coordinates (temperature and pressure in this example) change discontinuously (abruptly). For example, the heat capacity of a container filled with ice will change abruptly as the container is heated past the melting point. The open spaces, where the [[Thermodynamic free energy|free energy]] is [[analytic function|analytic]], correspond to single phase regions. Single phase regions are separated by lines of non-analytical behavior, where [[phase transition]]s occur, which are called '''phase boundaries'''.
In the diagram on the right, 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 (thermodynamics)|critical point]]. This reflects the fact that, at extremely high temperatures and pressures, the liquid and gaseous phases become indistinguishable,<ref>{{cite book |first=P. |last=Papon |first2=J. |last2=Leblond |first3=P. H. E. |last3=Meijer |title=The Physics of Phase Transition : Concepts and Applications |location=Berlin |publisher=Springer |year=2002 |isbn=978-3-540-43236-4 }}</ref> in what is known as a [[supercritical fluid]]. In water, the critical point occurs at around ''T''<sub>c</sub> = {{convert|647.096|K|C}}, ''p''<sub>c</sub> = {{convert|22.064|MPa|atm|abbr=on}} and ''ρ''<sub>c</sub> = 356 kg/m³.<ref>The International Association for the Properties of Water and Steam [http://www.iapws.org/relguide/fundam.pdf "Guideline on the Use of Fundamental Physical Constants and Basic Constants of Water"], 2001, p. 5</ref>
For most substances, the solid–liquid phase boundary (or fusion curve) in the phase diagram has a positive [[slope]] so that the melting point increases with pressure. This is true whenever the solid phase is [[Density|denser]] than the liquid phase.<ref name=Whitten>{{cite book |last1=Whitten |first1=Kenneth W. |last2=Galley |first2=Kenneth D. |last3=Davis |first3=Raymond E. |date=1992 |title=General Chemistry. |edition=4th |page=477 |publisher=Saunders College Publishing}}</ref> The greater the pressure on a given substance, the closer together the molecules of the substance are brought to each other, which increases the effect of the substance's [[intermolecular forces]]. Thus, the substance requires a higher temperature for its molecules to have enough energy to break out of the fixed pattern of the solid phase and enter the liquid phase. A similar concept applies to liquid–gas phase changes.<ref name=Dorin>{{cite book |title=Chemistry : The Study of Matter Prentice |last1=Dorin |first1=Henry |last2=Demmin |first2=Peter E. |last3=Gabel |first3=Dorothy L. |edition=Fourth |pages=266–273 |isbn=978-0-13-127333-7 |publisher=[[Prentice Hall]] }}</ref>
Water is an exception which has a solid-liquid boundary with negative slope so that the melting point decreases with pressure. This occurs because ice (solid water) is less dense than liquid water, as shown by the fact that ice floats on water. At a molecular level, ice is less dense because it has a more extensive network of [[hydrogen bond]]ing which requires a greater separation of water molecules.<ref name=Whitten/> Other exceptions are [[antimony]] and [[bismuth]].<ref>{{cite book |last1=Averill |first1=Bruce A. |last2=Eldredge |first2=Patricia |date=2012 |title=Principles of General Chemistry |chapter=11.7 Phase Diagrams |chapter-url=https://2012books.lardbucket.org/books/principles-of-general-chemistry-v1.0/s15-07-phase-diagrams.html |publisher=Creative Commons}}</ref><ref>{{cite book |last1=Petrucci |first1=Ralph H. |last2=Harwood |first2=William S. |last3=Herring |first3=F. Geoffrey |date=2002 |title=General Chemistry. Principles and Modern Applications |edition=8th |page=477 |publisher=Prentice Hall}}</ref>
The value of the slope dP/dT is given by the [[Clausius–Clapeyron relation|Clapeyron equation]] for fusion (melting)<ref>{{cite book |last1=Laidler |first1=Keith J. |last2=Meiser |first2=John H. |date=1982 |title=Physical Chemistry |pages=173–4 |publisher=Benjamin/Cummings}}</ref>
:<math>\frac{\mathrm{d}P}{\mathrm{d}T} = \frac{\Delta_{fus} H}{T\,\Delta_{fus} V}, </math>
where ΔH<sub>fus</sub> is the heat of fusion which is always positive, and ΔV<sub>fus</sub> is the volume change for fusion. For most substances ΔV<sub>fus</sub> is positive so that the slope is positive. However for water and other exceptions, ΔV<sub>fus</sub> is negative so that the slope is negative.
==== Друга термодинамичка својства ====
In addition to temperature and pressure, other thermodynamic properties may be graphed in phase diagrams. Examples of such thermodynamic properties include [[specific volume]], [[specific enthalpy]], or specific [[entropy]]. For example, single-component graphs of temperature vs. specific entropy (''T'' vs. ''s'') for water/[[steam]] or for a [[refrigerant]] are commonly used to illustrate [[thermodynamic cycle]]s such as a [[Carnot cycle]], [[Rankine cycle]], or [[vapor-compression refrigeration]] cycle.
Any two thermodynamic quantities may be shown on the horizontal and vertical axes of a two-dimensional diagram. Additional thermodynamic quantities may each be illustrated in increments as a series of lines – curved, straight, or a combination of curved and straight. Each of these '''iso-'''lines represents the thermodynamic quantity at a certain constant value.
[[Датотека:TS-Wasserdampf engl.png|thumb|center|500px|Temperature vs. specific entropy phase diagram for water/steam. In the area under the red dome, liquid water and steam coexist in equilibrium. The critical point is at the top of the dome. Liquid water is to the left of the dome. Steam is to the right of the dome. The blue lines/curves are '''isobars''' showing constant pressure. The green lines/curves are '''isochors''' showing constant specific volume. The red curves show constant quality.]]
{| class="wikitable" border="1"
| [[Image:Mollier enthalpy entropy chart for steam - US units.svg|thumb|300px]] || [[Image:Pressure-enthalpy chart for steam, in US units.svg|thumb|300px]] || [[Image:Temperature-entropy chart for steam, US units.svg|thumb|300px]]
|-
| enthalpy–entropy (''h''–''s'') diagram for steam || pressure–enthalpy (''p''–''h'') diagram for steam || temperature–entropy (''T''–''s'') diagram for steam
|}
=== Тродимензиони дијаграми ===
[[Датотека:pVT 3D diagram.png|thumb|250px|''p''–''v''–''T'' 3D diagram for fixed amount of pure material]]
[[Датотека:3D_representation_of_several_phases_of_water.jpg|мини|250п|лево|3D phase diagram of water fluids and selected ices]]
It is possible to envision three-dimensional (3D) graphs showing three thermodynamic quantities.<ref>{{cite book |last1=Zemansky |first1=Mark W. |last2=Dittman |first2=Richard H. |year=1981 |title=Heat and Thermodynamics |edition=6th |at=Figs. 2-3, 2-4, 2-5, 10-10, P10-1 |publisher=[[McGraw-Hill]] |isbn=978-0-07-072808-0}}</ref><ref>Web applet: [http://biomodel.uah.es/Jmol/plots/phase-diagrams/ 3D Phase Diagrams for Water, Carbon Dioxide and Ammonia]. Described in {{cite journal |last1=Glasser |first1=Leslie |last2=Herráez |first2=Angel |last3=Hanson |first3=Robert M. |year=2009 |title=Interactive 3D Phase Diagrams Using Jmol |journal=[[Journal of Chemical Education]] |volume=86 |issue=5 |pages=566 |doi=10.1021/ed086p566}}</ref> For example, for a single component, a 3D Cartesian coordinate type graph can show temperature (''T'') on one axis, pressure (''p'') on a second axis, and specific volume (''v'') on a third. Such a 3D graph is sometimes called a ''p''–''v''–''T'' diagram. The equilibrium conditions are shown as curves on a curved surface in 3D with areas for solid, liquid, and vapor phases and areas where solid and liquid, solid and vapor, or liquid and vapor coexist in equilibrium. A line on the surface called a '''triple line''' is where solid, liquid and vapor can all coexist in equilibrium. The critical point remains a point on the surface even on a 3D phase diagram.
For water, the 3D ''p''–''v''–''T'' diagram is seen here:<ref>{{cite journal |last1=David |first1=Carl |title=Verwiebe's "3-D" Ice phase diagram reworked |journal=Chemistry Education Materials |url=http://digitalcommons.uconn.edu/chem_educ/94|date=2016-08-08 }}</ref>
An [[orthographic projection]] of the 3D ''p''–''v''–''T'' graph showing pressure and temperature as the vertical and horizontal axes collapses the 3D plot into the standard 2D pressure–temperature diagram. When this is done, the solid–vapor, solid–liquid, and liquid–vapor surfaces collapse into three corresponding curved lines meeting at the triple point, which is the collapsed orthographic projection of the triple line.
== Експериментално и рачунско одређивање ==
Линија 17 ⟶ 66:
== Примена ==
Рачунски [[фазни дијаграм]]и се у већини случаја поклапају (уз одређену грешку која је иначе мера неидеалности постигнуте равнотеже) са експериментално одређеним [[Фазни дијаграм|фазним дијаграмима]]. Поготово је њихова улога велика у екстраполацији података за области [[Фазни дијаграм|фазног дијаграма]] у којима нема експерименталних мерења. Наука која је прва развила и применила [[Фазни дијаграм|фазне дијаграме]] била је [[металургија]], због изузеног значаја фазног дијаграма у производњи и пререди [[Гвожђе|гвожђа]] и [[челик]]а. [[Куриозитет]] је у томе да је управо фазни дијаграм који описује челик, један од еклатантних примера неравнотежног фазног дијаграма.
== Референце ==
{{reflist}}
== Спољашње везе ==
{{Commonscat|Phase diagrams}}
* -{[https://web.archive.org/web/20080216023642/http://www.sv.vt.edu/classes/MSE2094_NoteBook/96ClassProj/examples/kimcon.html Iron-Iron Carbide Phase Diagram Example]}-
* -{[http://www.soton.ac.uk/~pasr1/build.htm How to build a phase diagram]}-
* -{[http://www.chm.davidson.edu/ChemistryApplets/PhaseChanges/PhaseDiagram1.html Phase Changes: Phase Diagrams: Part 1]}-
* -{[https://web.archive.org/web/20060427102513/http://www.matter.org.uk/steelmatter/metallurgy/6_1_3_1.html Equilibrium Fe-C phase diagram]}-
* -{[http://mtdata.software.googlepages.com/periodictableSolders.htm Phase diagrams for lead free solders]}-
* -{[http://www.doitpoms.ac.uk/miclib/phase_diagrams.php DoITPoMS Phase Diagram Library]}-
* -{[http://www.doitpoms.ac.uk/tlplib/phase-diagrams/index.php DoITPoMS Teaching and Learning Package – "Phase Diagrams and Solidification"]}-
* -{[https://rd.springer.com/article/10.1007/s11669-014-0343-5 Phase Diagrams: The Beginning of Wisdom – Open Access Journal Article]}-
* -{[https://av.tib.eu/media/34658?pag=1 Binodal curves, tie-lines, lever rule and invariant points – How to read phase diagrams] (Video by SciFox on * [https://av.tib.eu/ TIB AV-Portal])}-
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