phasediagram 2015

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Phase DiagramsA Description of phase diagrams.

See the presentations:Phases

Daltons lawfor some background information.


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Phase Diagrams

In the discussion of Raoultslaw, the vapor pressure of

water at 50EC was used.From the CRC* handbookgave this vapor pressure:

From this one can see thatthe vapor pressure of waterat 50EC is:

142.60 torr

*Handbook of Chemistry and Physics, C. D. Hodgman, R. C. Weast and S. M. Shelby, eds.,Chemical Rubber Publishing Co. Handbook, 40th ed. (1958) Cleveland, OH


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One could plot this data, temperature as theabscissa and pressure as the ordinate:

Temperature /

C

Phase Diagrams


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Temperature /

C

Phase Diagrams

This line

represents the

equilibrium:

H2O(l) H2O(g)

(l) /liquid(g)/gas

(s)/

solid(aq) /aqueous


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Temperature /

C

Phase Diagrams

This line

represents the

equilibrium:

H2O(l) H2O(g)

and it is called theliquid-gas phaseboundary


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There is another line on this diagram that couldbe drawn.

Temperature /

C

Phase Diagrams

This line

represents the

equilibrium:

H2O(s) H2O(l)

recall that:(l) /liquid(s)/solid


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This line

represents the

equilibrium:

H2O(s) H2O(l)

and it is called thesolid-liquid phaseboundary

There is another line on this diagram that couldbe drawn.

Phase Diagrams

Temperature /

C


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Temperature /

C

At the low end of this diagram are another features.

Phase Diagrams

Temperature /

C


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Temperature /

C

Phase Diagrams


This line

represents the

equilibrium:

H2O(s) H2O(g)


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Temperature /

C

Phase Diagrams


This line

represents the

equilibrium:

H2O(s) H2O(g)

and it is called thesolid-gas phaseboundary


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Temperature /

C

Phase Diagrams


This intersection

represents the

3- way equilibria:

H2O(s) H2O(g)

H2O(l)


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Temperature /

C

Phase Diagrams


This intersection

represents the

3- way equilibria:

H2O(s) H2O(g)

H2O(l)

it is called the

triple point


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Phase Diagrams

At the high end of this diagram there is a point atwhich the liquid and the gas density becomes thesame.

This point is calledthe critical point

Temperature /

C


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Temperature /

C

Phase Diagrams

At the high end of this diagram there is a point atwhich the liquid and the gas density becomes thesame.

This point is calledthe critical point.

Above this pointthe fluid is referredto as the super-critical fluid.


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Phase Diagrams

Temperature /

C

liquid

gas

solid

Other compounds have similar phase diagrams.Here is the phase diagram for CO2.


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Phase Diagrams

Temperature /C

liquid-gas boundary CO2(s) CO2(g)

liquid

gas

solid



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Phase Diagrams

Temperature /Csolid-gas boundaryCO2(s) CO2(g) liquid-gas boundary CO2(s) CO2(g)

liquid

gas

solid



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Phase Diagrams

Temperature /Csolid-gas boundaryCO2(s) CO2(g) liquid-gas boundary CO2(s) CO2(g)

liquid

gas

solid

liquid-solid boundaryCO2(s) CO2(l)



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Phase Diagrams

Temperature /C

triple pointCO2(s) CO2(l) CO2(g)

solid-gas boundaryCO2(s) CO2(g)



liquid

gas

solid



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Phase Diagrams

Temperature /

C

critical point





liquid

gas

solid



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Phase Diagrams


Temperature /C

critical point

supercritical fluid





liquid

gas

solid


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Phase Diagrams

Summary - All metals and molecular solids whichdo not decompose and many ionic solids havesimilar phase diagrams with the following features:


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Phase Diagrams


solid phase


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Phase Diagrams


solid phaseliquid phase


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Phase Diagrams


solid phaseliquid phasegas phase


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Phase Diagrams


solid phaseliquid phasegas phasesolid-liquid phase boundary ( solidliquid )


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Phase Diagrams


solid phaseliquid phasegas phasesolid-liquid phase boundary ( solidliquid )solid-gas phase boundary ( solidgas )


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Phase Diagrams


solid phaseliquid phasegas phasesolid-liquid phase boundary ( solidliquid )solid-gas phase boundary ( solidgas )liquid-gas phase boundary ( liquidgas )


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Phase Diagrams



triple point ( solid

liquid

gas )


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Phase Diagrams




liquid

gas )critical point


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Phase Diagrams


solid phaseliquid phasegas phase

solid-liquid phase boundary ( solidliquid )solid-gas phase boundary ( solidgas )liquid-gas phase boundary ( liquidgas )


liquid

gas )critical pointsupercritical fluid


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The End of Phase Diagrams

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