Fred J. Grieman

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Fred J. Grieman

• Pure Substance
• Phase Diagram Review
• Solid Phase transitions
• II. Solution Equilibria
• A. Insoluble phases
• Extraction, Vitamins, Chromatography
• B. Soluble Phases Binary Solutions
• Vapor pressure escaping tendency
• Ideal Solutions Raoults Law
• Raoult Diagrams
• Deviations

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Water Phase Diagrams
Many solid phases for water allotropes Equilibriu
m lines between allotropes
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Possibly different solid phases -
Allotropes Carbon 3 solid allotropes
graphite, diamond, buckminsterfullerene Equilib
rium lines between these phases as well
HPHT high pressure, high temperature CVD
chemical vapor deposition
nanotubes
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How did the thermodynamics of phase changes
affect modern European History? Cheap white
buttons! Made of tin (Sn)

Two Allotropes of Tin White Sn (? -Sn)

Gray Sn (? -Sn) strong and reasonably rigid
brittle and
crumbly ?Gof,298 0, ?Hof,298 0
?Gof,298 0.13, ?Hof,298
-2.09
Stable form at 298K, 1 atm. ? Solid
phase transition ?-Sn ? ?-Sn
At what temperature does equilibrium occur?
?Gop.c ? ?Gopc 0 From App. D (at 298K)
?Hop.c -2090 J/mol ?Sop.c. -7.4
J/molK ?Gop.c 0 ?Hºp.c. - Tpc?Sºp.c. So
Tpc ?Hºp.c. / ?Sºp.c 282 K Actually Tpc
286 K 13 oC 55 oF
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White Sn (? -Sn) gray Sn (? -Sn) strong
and rigid brittle and crumbly
Phase diagram Slope of equilibrium curve?
Clapeyron equation dP/dT
?Hpc/T?Vpc ?Hopc,286 -2.09 kJ/mol, ?V
? d(ß) 7.31 g/mL d(a) 5.75 g/mL
M(Sn) 118.7 g/mol V(ß) 16.2 mL/mol V(a)
20.6 mL/mol ?V 4.4 mL/mol dP/dT
-2.09/4.4(T) lt 0 negative slope P(atm)
ß 1 a
286 298 T(K)
Which is more stable at higher pressure?
ß
So, affect on history? When French fought
Russians in the winter (T ltlt 286 K)
French pewter uniform buttons spontaneously
changed from White Tin to Gray Tin Buttons
crumbled, fell off and soldiers froze
Napoleon's army had to retreat!
Now move on from pure substances to solutions
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