MLZ 325
MATERIALS THERMODYNAMICS I
EXAMPLE PROBLEMS
CHAPTER 7
SET 2
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Example 1
Calculate the approximate pressure required to distill Hg at 100C.
ln patm   
7611
 0.795  ln T  17.168
T
---------------------------------------------------------------------------------------------------------Answer
ln patm   
7611
 0.795  ln 373  17.168  7.945
373
 patm   exp  7.945  3.544  10 4 atm
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Example 2 (Midterm I, Fall Semester 2010-2011)
The molar volumes of solid and liquid lead (Pb) at the normal melting temperature of
Pb are, respectively, 18.92 and 19.47 cm3. Calculate the pressure which must be applied
to Pb in order to increase its melting temperature by 20ºC.
J
mole
H m  4180
Tn.m. p Pb)  600 K
---------------------------------------------------------------------------------------------------------Answers
H
 dP 

 
 dT  eq T  V

Pf
1
dP 
 lt  atm 

 101.325 J 
4810 J   
19.47 cm
3
 1 lt 

 18.92 cm 3   3
3 
 10 cm 

dT
 620 
 86310.93  ln 
  2830 atm
T
 600 
620
600
1
Pf
 P   dP  Pf  1  2830 atm
1
 Pf  2831 atm
2