CHE 303 (Winter 1997)
Answer to Final
I.
II.
III.
IV.
V.
VI.
VII.
VIII.
IX.
1) 0.65237, 2) 0.14267, 3) 0.24018, 4) 0.51474, 5) 0.30873
1) 250 J/mol, 2) 257.92 J/mol, 3) 126.12 J/mol, 4) 260.0 J/mol, 5) 150.0 J/mol
1) 1.7514, 2) 0.40, 3) 344.525 oK
1) 81.177, 2) -2.5469
1) 0.92928, 2) 13.339, 3) 2.1183 bar, 4) 1.10
1) 15, 2) C, 3) 3
1) 0.59373, 2) 48.299
B
1) 250 oF, 2) -140 Btu/lb, 3) 610 Btu/lb
Answers to 1997 Quizzes
Quiz #1
I. 4 (A and B are false)
II. 1) 300 J/mol
2) 308.82
3) 201.17
4) 315.0
5) 220.0
III. 1) 0.3333
2) 0.5833
3) 0.3
IV. V=117.66 cm3
Quiz #2
I. The enthalpy of a binary mixture liquid system of species 1 and 2 at fixed T and P is
represented by the equation
H = 200x + 250 (1-x) + x (1-x)[20x + 35 (1-x)]
where H is in J/mol, x = mole fraction of species 1
H(par,1) = H + (1-x)(dH/dx), and H(par,2) = H - x (dH/dx)
1. The partial molar enthalpy of species 1 at infinite dilution H(par, 1, infinite dilution) = 235
J/mol
2. The partial molar enthalpy of species 2 at infinite dilution H(par, 2, infinite dilution) = 270
J/mol
II. Consider an osmotic equilibrium system of four components, two mixtures at different
pressures and separated by a rigid membrane permeable to only two of the species present.
1. The number of intensive variables required to specify this system is 10
2. The degree of freedom for this system is 7
III. Consider a chemical equilibrium system consisting of CO2, CO, C, CH4, H2, H2O, and N2.
The independent equations required to describe the system are:
A
B
C
C + CO2 = 2CO
C + CO2 = 2CO
C + H2O = CO + H2
C + 2H2 = CH4
C + H2O = CO + H2 C + 2H2 = CH4
D
None of the above
C + 2H2 = CH4
IV. The rank of the following matrix is 3
1
0
1
1
2
1
3
1
0
2
2
1
1
0
1
0
2
1
3
0
0
0
0
2
1
0
1
0
1
1
2
1
V. A. In a closed system at constant T and P, a spontaneous process will increase Gibbs free
energy, G, until a maximum value for G is reached at equilibrium.
B. Chemical potential is an intensive property.
1. A and B are true
2. Only A is true
3. Only B is true
4. A and B are false
VI. A. The size and thermodynamic state of a pure single phase system would be fixed by two of
its intensive state variables.
B. The chemical potential of a pure substance is equal to its specific Gibbs free energy, G.
1. A and B are true
2. Only A is true
3. Only B is true
4. A and B are false
VII. A. For a pure substance at equilibrium, the temperature and pressure of phases are equal but
chemical potentials of phases may be different.
B. For an isolated system, a process that would move the system to a less constrained equilibrium
state will decrease the entropy of the system.
1. A and B are true
2. Only A is true
3. Only B is true
4. A and B are false
VIII. A. The Gibbs free energies of two phases of a pure substance at equilibrium are equal.
B. The entropies of two phases of a pure substance at equilibrium are equal.
1. A and B are true
2. Only A is true
3. Only B is true
4. A and B are false
CHE 303
Quiz #3
I. 1)5 2)11 3)2
II. 1)270.02 psia 2)56.7 psia
III. 3-Only B is true
IV. 2-Only A is true
V. 1)-5.68*10^4 J 2)-1.101*10^5 J
VI. 1-A and B are true
Answers for quiz #4 (Winter 97)
1. 3- only B is true
2. 3- Only B is true
3. 4-A and B are false
4. 3-Only B is true
5. a. 0.595
b. 0.2324
6. 195.59 kPa
7. a. 183.3 psia
8.
477.33 cm3
Quiz #5
1. Consider an osmotic equilibrium system of three components, two mixtures at
different pressures and separated by a rigid membrane permeable to only two of
the species present.
The degree of freedom for this system is
5
.
2. A. The fugacity of some non simple liquid can be estimated from the equations of
state.
B. The fugacity of all vapor mixtures can be estimated from the equations of
state.
1. A and B are true 2. Only A is true 3. Only B is true 4. A and B are false
3. A. The critical point of a mixture is the temperature and pressure at which the
vapor and liquid phases of a mixture of given composition become identical.
B. Fugacity predictions based on equations of states will be less accurate than
predictions from the principle of corresponding states.
1. A and B are true 2. Only A is true 3. Only B is true 4. A and B are
false.
4.
Consider a mixture of acetone (1) and (2) water at a total pressure of 101.3 KPa.
The Wilson equation is used to estimate the activity coefficients.

 21  12  0.1173
ln  1   ln x1  x 212  x 2   12 
,
 x1 x 2 12 x 2  x1 21   21  0.4227
Vapor pressure data
Ln P1sat=14.7171-2975.95/(T-34.5228)
T is in 0K and P is kPa
sat
Ln P2 =16.5362-3985.44/(T-38.9978)
A. At x1=0.1
γ1 =
5.4291
.
B. The boiling point of pure acetone is
329.2 K
.
C. Given γ2 = 1.148 at the bubble point of 335.80K where x1=0.2, y1= 0.797 .
D. Given γ2= 1.148, x1=0.3, and y1=0.8127, the dew point in (0K) is
336.990K
5. The following data have been reported for the constant-pressure heat capacity of a
water-ethanol mixture at 250C.
Wt% Ethanol
Cp(J/g0C)
Wt% Ethanol
Cp(J/g0C)
0
4.156
60
3.120
40
3.482
100
2.449
Molecular weight of ethanol =46.07, MW of water = 18.02
A. At 40 wt% ethanol
B. At 60 wt% ethanol
Cmix(J/mol0C) =
ΔCmix(J/mol0C)=
82.95 J/mol0C .
-.3350
( pg 390)
6. A. A maximum boiling azeotrope occurs when there are positive deviations from
Raoult’s law.
B.In a minimum-boiling azeotrope, the activity coefficient of at least one of the
species in the mixture is greater than unity.
1. A and B are true 2. Only A true 3. Only B is true
4. A and B are false