ECHE 311/SPRING 2015
Problem Set # 9
Similar Problems will be given in Exam 2
1. The following is set of activity-coefficient data for the binary liquid system as determined
by VLE.
x1
1
0.0523
0.1299
0.2233
0.2764
0.3482
0.4187
0.5001
1.202
1.307
1.295
1.228
1.234
1.180
1.129
2
x1
1.002
1.004
1.006
1.024
1.022
1.049
1.092
0.5637
0.6469
0.7832
0.8576
0.9388
0.9813
1
2
1.120
1.076
1.032
1.016
1.001
1.003
1.102
1.170
1.298
1.393
1.600
1.404
Inspection of these experimental values suggest that they are noisy, but the question is whether
they are consistent, and therefore possibly on average correct.
(a) Find experimental values for
values of
G E / RT
and plot them along with the experimental
ln  1 and ln  2 on a single graph.
E
(b) Develop a valid correlation for the composition dependence of G / RT and show lines
on the graph of part (a) that represent this correlation for all thee of the quantities plotted
there.
(c) Apply the consistency test described bellow and in Example (11/Fifth Edition SVNA) to
these data and draw a conclusion with respect to this test.
2. The total enthalpy of a binary liquid system of species 1 and 2 at fixed T and P is
given by: See Example 11.4 in your textbook (page 389)
H=400x1+600x2+x1x2 (40x1+20x2)
a) Apply Eq (11.7 in your textbook) to Equation A in the Example to verify
Eqs (B) nad (C). Find expression for the molar enthalpies of species 1 and
2.
b) Show that Eqs (B) and (C) combine in accord with Eq. (11.11) to regenerate
Eq. A.
c) Show that these expressions satisfy the Gibs/Duhem equation.
d) Plot values of H, H 1(x1) and H 2(x2) calculated by equations (A), (B), (C)
vs. x1 .
3. Solve Problems 11.19; 11.23 from your textbook