MSE 308
Thermodynamics of Materials
Dept. of Materials Science & Engineering
Spring 2005/Bill Knowlton
Problem Set 7 Solutions
1. The following reaction:
Pb + ½ O2 = PbO
is on page 119-123 of Gaskell. Repeat this problem using the approach:
∆H rxn = ∑ H prod . − ∑ H react .
by doing the following:
a. Provide a list of materials parameters necessary to do the problem and similar to
the one I handed out in class.
Table 6.1 on page 121 of Gaskell gives much of this information.
b. Draw a schematic of H versus T diagram.
Pb (g) + 1/2O2(g)
∆H
Pb (l) + 1/2O2(g)
Pb (s) + 1/2O2(g)
∆HPbl->g
∆HPbs->l
2023K
600K
T
1159K
PbO(l)
PbO(s)
∆HPbO2l->g
MSE 308
Thermodynamics of Materials
c. Determine
∑H
prod .
Dept. of Materials Science & Engineering
Spring 2005/Bill Knowlton
at a temperature of 1300 K.
Note: that we do not have the necessary data to determine
∑H
react .
∑H
prod .
,
or ∆Hrxn at 1300K. We have the necessary data for temperatures
up to 1159K. Hence, the calculations will be based on finding ∆Hrxn at 1159K.
∑H
prod .
298
= ∆H PbO
+∫
1159
298
solid
CPbO
dT
= -219, 000 J + 49,442J
= −169,558 J
d. Determine
∑H
∑H
react .
react .
at a temperature of 1300 K.
1159 ⎛
1
⎛ solid 1 gas ⎞
⎞
298
solid
CPb + CO2 ⎟ dT + ∆H PbO
+ ∫ ⎜ CPb
+ COgas
⎜
⎟ dT
2
298
298
2
2
⎝
⎠
⎝
⎠
= 3,116J + 4,818 J + 25,922J
=∫
600
= 43,855J
e. Determine ∆H rxn at a temperature of 1300 K.
∆H rxn = ∑ H prod . − ∑ H react .
= −169,558 J + 43,855J
= -213,413J
MSE 308
Thermodynamics of Materials
Dept. of Materials Science & Engineering
Spring 2005/Bill Knowlton
2. The following reaction:
UF4 + 2 Mg = 2MgF2 + U
is on page 137-142 of Gaskell. Repeat this problem using the approach:
∆H rxn = ∑ H prod . − ∑ H react .
by doing the following. First, provide a list of materials parameters necessary to do the
problem and similar to the one I handed out in class and second, draw a schematic of H
versus T diagram. Then:
a. Determine ∑ H prod . at a temperature of 1118 K.
MSE 308
Thermodynamics of Materials
b. Determine
∑H
react .
Dept. of Materials Science & Engineering
Spring 2005/Bill Knowlton
at a temperature of 1118 K.
c. Determine ∆H rxn at a temperature of 1118 K.
MSE 308
Thermodynamics of Materials
Dept. of Materials Science & Engineering
Spring 2005/Bill Knowlton
3. For either reaction in problem 1 or 2, provide a solution to determining ∆S rxn
Use the same approach in determine ∆Srxn as you did with solving for ∆Hrxn
and derive a numerical solution.
4. For either reaction in problem 1 or 2, provide a solution to determining ∆Grxn
Use the approach: ∆Grxn = ∆Hrxn - T ∆Srxn and derive a numerical solution.
Chapter 6 problems in Gaskell: 6.1
Gaskell 6.1:
MSE 308
Thermodynamics of Materials
Gaskell 6.1 (cont):
Dept. of Materials Science & Engineering
Spring 2005/Bill Knowlton