ConcepTests in Chemical Engineering Thermodynamics Unit 3: Fluid Phase Equilibria in Mixtures

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ConcepTests in Chemical Engineering
ThermodynamicsUnit 3 Fluid Phase Equilibria in
Mixtures
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Day 38
38.___ Recall, eij (eii ejj )½ (1- kij )1.
Which (A or B) corresponds to kij gt 0?2. Which
corresponds to components liking each other?3.
Which corresponds to a higher fugacity
mixture?4. Which will give the highest bubble
point pressure?
3
39.1. Components (A and B) are in VLE. One mole
of liquid (xA0.4) and 0.1 mol of vapor (yA0.7)
are present. When 0.5 mol of A is added and the
system goes to equilibrium at the same T and P,
what happens? (cf. Falconer, CEE 3864, 2004)
Day 39 VLE Intro
(a) The amount of liquid increases.(b) The
amount of liquid decreases.(c) The concentration
of A in the gas phase increases.(d) The
concentration of A in the liquid phase increases.

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39.2. The fugacity (bar) of water at 150C and 100
bar closer to ___. (cf. Falconer, CEE 3864, 2004)
Day 39 VLE Intro
(a) 1(b) 5(c) 50(d) 100
5
39.3. Two identical flasks at 45C are connected
by a thin tube. Flask A contains water and flask
B contains the same amount of a 95/5 mixture of
water and salt. After 5 hours ___. (cf. Falconer,
CEE 3864, 2004)
Day 39 VLE Intro
(a) Flask A has more water.(b) Flask B has more
water.(c) The amounts of water do not change
since they are at the same temperature.(d) All
the salt moves to flask A.
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39.4. Estimate the equilibrium partial pressure
of ethanol (bars) in air above a solution of
50mol ethanol and water at 311K. You may assume
an ideal solution and apply the shortcut vapor
pressure equation. (Tc516,Pc6.4,w0.64)
Day 39 VLE Intro
(a) 0.1(b) 0.2(c) 0.4(d) 0.8
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40.1 Ethanol has a lower flammability limit (LFL)
of 4.3. What concentration (mol) of ethanol in
water is necessary for the solution to burn at
311K (assume IS thermo).
Day 40 VLE Intro
(a) 0.1(b) 0.2(c) 0.4(d) 0.8
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42.1 The equation of state below has been
suggested for a new equation of state. Derive
the expression for the Helmholtz energy departure
(A-Aig)TV/RT.Z 1 4b?/(1-b?) where b
?xibi
Day 42 EOS VLE
(a) 4/(1-b?) (b) (-4/bi)/(1-b?) (c)
(-4/bi)ln(1-b?) (d) -4ln(1-b?)
9
42.2 The equation of state below has been
suggested for a new equation of state. Derive
the expression for the fugacity coefficient
ln(fk).Z 1 4b?/(1-b?) where b ?xibi
Day 42 EOS VLE
(a) 4b?/(1-b?) ln(Z) (b) -4ln(1-b?) ln(Z)
(c) 4bk? /(1-b?) ln(Z) (d) -4ln(1-b?)
4bk? /(1-b?) ln(Z)
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43.1 The equation of state below has been
suggested for a new equation of state. Derive
the expression for the Helmholtz energy departure
(A-Aig)TV/RT.Z 1 4b?/(1-b?) where b
?xibi
Day 43 QikQiz3.1
(a) -4/(1-b?)2 (b) 4ln(1-b?) (c) -2ln(1-b?)
(d) -4ln(1-b?)
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43.2 The equation of state below has been
suggested for a new equation of state. Derive
the expression for the fugacity coefficient
ln(fk).Z 1 4b?/(1-b?) where b ?xibi
Day 43 QikQiz3.1
(a) -4ln(1-b?) - 4bk?/(1-b?) ln(Z) (b)
-4ln(1-b?) 4bk?/(1-b?) ln(Z) (c)
4bk?/(1-b?) ln(Z) (d) -4bk?/(1-b?) ln(Z)
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43.3 Estimate the bubble pressure (MPa) of
acetone(1,MW58) nPentane(2,MW72) at 32.0?C
and 21wt acetone from the ideal shortcut model.
The shortcut vps are P1sat 0.044, P2sat
0.090 MPa
Day 43 QikQiz3.1
(a) 0.1013(b) 0.0530(c) 0.0790(d) 0.0810
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43.4 For liquid acetone(1)nPentane(2), br
0.786 at 305K and 25mol acetone. Estimate the
Z-factor from the vdW model assuming kij0.FYI
aii J2/(kmol2-MPa) bi J/(mol-MPa)amix
2.061 bmix 137
aii bi xi a1i a2i
1.804 112 0.25 1.804 1.969
2.150 145 0.75 1.969 2.150
S xibi 137 S xiaji 1.928 2.061
(a) 0.0001(b) 0.001(c) 0.01(d) 0.1
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43.5 For liquid acetone(1)nPentane(2), br
0.786 at 32.0?C and 25mol acetone. Estimate
the liquid fugacity coefficient of acetone from
the vdW model assuming kij0.FYI aii
J2/(kmol2-MPa) bi J/(mol-MPa)amix 2.061
bmix 137
aii bi xi a1i a2i
1.804 112 0.25 1.804 1.969
2.150 145 0.75 1.969 2.150
S xibi 137 S xiaji 1.928 2.061
(a) 0.0015(b) 0.015(c) 0.15(d) 1.5
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43.6 The bubble pressure of acetone(1)
nPentane(2) is 0.525 bars at 32.0?C and 82mol
acetone and acetones liquid fugacity coefficient
is 0.77 from the PREOS model. Estimate the
K-value for acetone assuming the vapor phase can
be treated as an ideal gas.
Day 43 QikQiz3.1
(a) 0.2(b) 0.4(c) 0.6(d) 0.8
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47.1 The equation of state below has been
suggested for a new equation of state. Derive
the expression for the Helmholtz energy departure
(A-Aig)TV/RT.Z 1/(1-2b?) where b ?xibi
Day 47 QikQiz3.2
(a) -2ln(1-2b?) (b) 2ln(1-2b?) (c)
-ln(1-2b?) (d) 2/(1-2b?)2
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47.2 The equation of state below has been
suggested for a new equation of state. Derive
the expression for the fugacity coefficient
ln(fk).Z 1/(1-2b?) where b ?xibi
Day 47 QikQiz3.2
(a) -ln(1-2b?) 2bk?/(1-2b?) ln(Z) (b)
-ln(1-2b?) 2bk?/(1-2b?) ln(Z) (c)
-2ln(1-2b?) 2bk?/(1-2b?) ln(Z) (d)
2ln(1-2b?) 2bk?/(1-2b?) ln(Z)
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47.3 The bubble pressure of acetone(1)nPentane(2
) is 1.013 bars at 32.0?C and 21wt acetone.
Estimate the kij find the inferred azeotropic
composition of the PREOS model. Indicate the
composition below.
Day 47 QikQiz3.2
(a) 0.20(b) 0.25(c) 0.30(d) 0.35
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47.4 The bubble pressure of acetone(1)nPentane(2
) is 1.013 bars at 32.0?C and 21wt acetone.
Estimate the bubble pressure from the ScHil model
assuming kij0.
Day 47 QikQiz3.2
(a) 0.0270(b) 0.0790(c) 0.0870 (d)
0.1013
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50.1 An azeotrope exists for n-butane(1)ethylene
Oxide(2) at 1.013 bars at -6.5?C and 78wt
butane. Estimate the azeotropic composition in
vol butane.
Day 50 Activity Models
Compound Tc(K) Pc(MPa) w CpIg/R MW d(cal/cc)1/2 r298
n-BUTANE 425.2 3.80 0.193 11.89 58 6.60 0.60
ETHYLENE OXIDE 469.0 7.10 0.200 5.80 44 10.62 0.89
(a) 70(b) 75(c) 80 (d) 85
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50.2 An azeotrope exists for n-butane(1)ethylene
Oxide(2) at 1.013 bars at -6.5?C and 78wt
butane. Estimate the activity coefficient of EtO
(g2) at the azeotropic composition and
temperature from the ScHil model assuming kij0.
Day 50 Activity Models
Compound Tc(K) Pc(MPa) w CpIg/R MW d(cal/cc)1/2 r298
n-BUTANE 425.2 3.80 0.193 11.89 58 6.60 0.60
ETHYLENE OXIDE 469.0 7.10 0.200 5.80 44 10.62 0.89
(a) 0.04(b) 1.06(c) 1.98 (d) 2.89
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50.4 An azeotrope exists for n-butane(1)ethylene
Oxide(2) at 1.013 bars at -6.5?C and 78wt
butane. Estimate the vapor pressure (mmHg) of
butane at the azeotropic composition and
temperature.
Day 50 Activity Models
Compound AntA AntB AntC
n-BUTANE 7.24 1184 273.2
ETHYLENE OXIDE 7.53 1313 273.2
(a) 755(b) 626(c) 588 (d) 397
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50.5 An azeotrope exists for n-butane(1)ethylene
Oxide(2) at 1.013 bars at -6.5?C and 78wt
butane. Estimate the bubble pressure (mmHg) at
the azeotropic composition and temperature from
the ScHil model assuming kij0.
Day 50 Activity Models
Compound Tc(K) Pc(MPa) w CpIg/R MW d(cal/cc)1/2 r298
n-BUTANE 425.2 3.80 0.193 11.89 58 6.60 0.60
ETHYLENE OXIDE 469.0 7.10 0.200 5.80 44 10.62 0.89
(a) 820(b) 790(c) 740 (d) 520
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50.4 An azeotrope exists for n-butane(1)ethylene
Oxide(2) at 1.013 bars at -6.5?C and 78wt
butane. Estimate the kij that matches the bubble
pressure (MPa) at the azeotropic composition and
temperature from the ScHil model.
Day 50 Activity Models
(a) 0.10(b) 0.01(c) -0.01 (d) -0.10
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51.1 An azeotrope exists for n-butane(1)ethylene
Oxide(2) at 1.013 bars at -6.5?C and 78wt
butane. Estimate the Antoine coefficients for
ethylene oxide from the shortcut eq.(Hint Use
Pc in mmHg to match units of existing coeffs.)
Day 50 Activity Models
Compound Tc(K) Pc(MPa) w CpIg/R MW d(cal/cc)1/2 r298
n-BUTANE 425.2 3.80 0.193 11.89 58 6.60 0.60
ETHYLENE OXIDE 469.0 7.10 0.200 5.80 44 10.62 0.89
(a) 8.53, 1313, 273.15(b) 7.53, 1313, 273.15(c)
6.53, 1313, 273.15(d) 5.53, 1313, 273.15
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51.2 Some activity models have contributions
likeDGE S Fidi where Fi is the volume fraction
and di is the solubility parameter. Derive the
contribution to the activity coefficient (lngk)
for this contribution to GE.
Day 50 Activity Models
(a) (Fkdk)/xk (SFidi )(1-Fk/xk) (b)
Vkdk/( S xiVi ) Vk ( S Fidi )/( S xiVi )2 (c)
Vkdk/( S xiVi ) (d) Vk dk2
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Qq3.3.1 Some activity models have contributions
likeDGE S Fidi where Fi is the volume fraction
and di is the solubility parameter. Derive the
contribution to the activity coefficient (lngk)
for this contribution to GE.
Day 51 QikQiz3.3
(a) (Fkdk)/xk (SFidi )(1-Fk/xk) (b)
Vkdk/( S xiVi ) Vk ( S Fidi )/( S xiVi )2 (c)
Vkdk/( S xiVi ) (d) Vk dk2
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Qq3.3.2 An azeotrope exists for
acetone(1)methanol(2) at 1.013 bars at 55.7?C
and 80mol acetone. Estimate the kij that matches
the bubble pressure (MPa) at the azeotropic
composition and temperature from the ScHil model.
Day 51 QikQiz3.3
(a) 0.10(b) 0.05(c) -0.05 (d) -0.10
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Day 51 QikQiz3.3
Qq3.3.3 An azeotrope exists for
acetone(1)methanol(2) at 1.013 bars at 55.7?C
and 80mol acetone. Compute the experimental
value for the activity coefficient of methanol at
the azeotrope.
(a) 3.1(b) 1.6(c) 1.4 (d) 0.7
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Day 51 QikQiz3.3
Qq3.3.4 An azeotrope exists for
acetone(1)methanol(2) at 1.013 bars at 55.7?C
and 80mol acetone. Compute the van Laar
parameter A21 that matches the azeotrope.
(a) 0.35(b) 0.45(c) 0.55 (d) 0.65
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52.1 Making your best estimate, arrange the
following mixtures from most ideal to least ideal
(1) Pentanehexane, (2) decanedecalin, (3)
1-hexenedodecanol, (4) pyridinemethanol, (5)
diethyl ethern-heptane.
Day 52 Activity Models
(a) 1, 2, 3, 4, 5 (b) 1, 2, 5, 3, 4(c) 5,
4, 1, 2, 3 (d) 2, 1, 5, 4, 3
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52.2 Which of the following properly depicts a
maximum boiling azeotrope?
Day 52 Activity Models
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52.3 Suppose the activity coefficients of all
components in a mixture are greater than unity.
Is the Gibbs Excess energy for this mixture
positive, negative, or zero? Why?
Day 52 Activity Models
(a) positive (b) negative(c) zero (d)
dont ask a mouse
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52.4 Use UNIFAC(VLE) to predict the activity
coefficient of para-methylPhenol (structure
below) in water at infinite dilution and 25?C.
Day 52 Activity Models
(a) 400 (b) 95(c) 45 (d) 30
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52.5 Estimate the infinite dilution activity
coefficient for a component in water when the
Margules 1-parameter is 2.
Day 52 Activity Models
(a) 7 (b) 4 (c) 2 (d) 1
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Day 53 (/41revisited)
53.___ Recall, eij (eii ejj )½ (1- kij )1.
Which (A or B) corresponds to kij gt 0?2. Which
corresponds to components liking each other?3.
Which corresponds to a higher fugacity
mixture?4. Which will give the highest bubble
point pressure?
37
54.1 Which of the following properly depicts a
maximum boiling azeotrope?
Day 54 Activity Models
38
54.2 We desire the relative volatility of
oxygen(1) ethyleneOxide(2) at 1.013 bars and
10mol oxygen. Estimate the Antoine coefficients
for ethylene oxide from the shortcut eq. (Hint
Use Pc in mmHg to match units of existing
coeffs.)
Day 54 Activity Models
(a) 8.53, 1313, 273.15(b) 7.53, 1313, 273.15(c)
6.53, 1313, 273.15(d) 5.53, 1313, 273.15
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54.3 We desire the relative volatility of
oxygen(1) ethyleneOxide(2) at 10 bars and 10mol
oxygen and L/F1. Estimate the temperature of
interest according to the ScHil model with kij0.
(FYI for O2 d4.0 and r2980.97)
Day 54 Activity Models
(a) 298(b) 181(c) 117(d) 45
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54.4 We desire the relative volatility of
oxygen(1) ethyleneOxide(2) at 10 bars and 10mol
oxygen and L/F1. Estimate the relative
volatility according to the ScHil model with
kij0. (FYI for O2 d4.0 and r2980.97)
Day 54 Activity Models
(a) 298(b) 181(c) 117(d) 45
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55.1 Which of the following is NOT an indicator
of possible azeotropic behavior?
Day 55 Activity Models
(a) similar boiling points(b) similar
solubility parameters(c) large activity
coefficients(d) positive Gibbs excess energy
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55.2 Which of the following indicates a small
value for the solubility parameter?
Day 55 Activity Models
(a) strong hydrocarbon content (b) a small
molecule with a high boiling point(c) strong
hydrogen bonding (d) a low critical pressure
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55.2 Which of these diagrams are not possible?
A. 2,6 B. 1,4,6 C. 2,5 D.
2,3,5 E. 3,5
3
2
1
5
4
6
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55.4 Components (A and B) are in VLE. One mole
of liquid (xA 0.4) and 0.1 mol of vapor (yA
0.7) are present. 0.5 mol of A is added and the
system goes to equilibrium at the same T and
P. What happens?JLF
A. The amount of liquid increases B. The amount
of liquid decreases C. The concentration of A in
the gas phase increases D. The concentration of
A in the liquid phase increases
yA0.7
xA 0.4
45
55.3 We desire the relative volatility of
oxygen(1) ethyleneOxide(2) at 10 bars and 10mol
oxygen and L/F1. Estimate the relative
volatility according to the ScHil model with
kij0. (FYI for O2 d4.0 and r2980.97)
Day 55 Activity Models
(a) 298(b) 181(c) 117(d) 45
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Day 56 QikQiz3.4
Qq3.4.1 An azeotrope exists for
vinylAcetate(1)methanol(2) at 1.013 bars at
58.5?C and 39 mol acetate. Compute the
experimental value for the activity coefficient
of methanol at the azeotrope. The Antoine
coefficients for vinylacetate areA7.21538 ,
B1299.069 , C226.967 (Hint Dont forget
Antoine coeffs for methanol.)
(a) 0.8(b) 1.3(c) 1.6 (d) 12
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Day 56 QikQiz3.4
Qq3.4.2 An azeotrope exists for
vinylAcetate(1)methanol(2) at 1.013 bars at
58.5?C and 39 mol acetate. Compute the van Laar
parameter A21 that matches the azeotrope.
(a) 0.55(b) 0.95(c) 1.35 (d) 1.65
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Day 56 QikQiz3.4
Qq3.4.3 An azeotrope might exist for
ethylAcetate(1) methanol(2) at 1.013 bars. Use
UNIFAC to estimate the infinite dilution
activity coefficient of ethylacetate at the
bubble point.
(a) 0.55(b) 1.35(c) 2.75 (d) 9.65
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Day 56 QikQiz3.4
Qq3.4.4 An azeotrope might exist for
ethylAcetate(1) methanol(2) at 1.013 bars. Use
UNIFAC to estimate the relative volatility of
methanol (LK) to dilute ethylacetate (HK) at the
bubble point.
(a) 0.55(b) 1.35(c) 2.75 (d) 9.65
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Day 56 LLE Intro
56.1 LLE might exist for nOctane(1) methanol(2)
at 1.013 bars. Use the ScHil model to estimate
the infinite dilution activity coefficient of
methanol in nOctane at 25C.
(a) 2(b) 3(c) 10 (d) 20
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Day 56 LLE Intro
56.2 LLE might exist for nOctane(1) methanol(2)
at 1.013 bars. Use the ScHil model to estimate
the infinite dilution activity coefficient of
nOctane in methanol at 25C.
(a) 13(b) 7000(c) 5e5 (d) 7e6
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Day 56 LLE Intro
56.3 LLE might exist for nOctane(1) methanol(2)
at 1.013 bars. Use the ScHil model to estimate
the mole fraction of nOctane in methanol at 25C.
(a) 0.5(b) 0.05(c) 0.001 (d) 0.00001
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Day 56 LLE Intro
56.2 LLE might exist for nOctane(1) methanol(2)
at 1.013 bars. Use the ScHil model to estimate
the GE/RT of methanol in nOctane at 25C and
50vol methanol.
(a) 0.75(b) 1.35(c) 2.75 (d) 9.65
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Day 56 LLE Intro
56.3 LLE might exist for nOctane(1) methanol(2)
at 1.013 bars. Use the ScHil model to estimate
the G/RT of methanol in nOctane at 25C and 60mol
methanol. (Hint we may assume that Gi/RT 0 for
all i.)
(a) 0.75(b) 1.35(c) 2.75 (d) 9.65
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56.4 Estimate the infinite dilution activity
coefficient for a component in water when the
Margules 1-parameter is 2.
Day 56 LLE
(a) 7 (b) 4 (c) 2 (d) 1
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Day 57 LLE Intro
57.1 LLE might exist for nOctane(1) methanol(2)
at 1.013 bars. Use the ScHil model to estimate
the ?M ? at 25C.
(a) 3.2(b) 5.2(c) 25 (d) 100
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Day 57 LLE Intro
57.2 LLE might exist for nOctane(1) methanol(2)
at 1.013 bars. Use the ScHil model to estimate
the ?O? at 25C.
(a) 3.2(b) 5.2(c) 25 (d) 100
58
Day 57 LLE Intro
57.3 LLE might exist for nOctane(1) methanol(2)
at 1.013 bars. Use the ScHil model to estimate
the solubility of nOctane in methanol at 25C.
(a) 3E-2(b) 3E-3(c) 3E-4 (d) 3E-6
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Day 57 LLE Intro
57.4 LLE might exist for nOctane(1) methanol(2)
at 1.013 bars. Use the UNIFAC(VLE) model to
estimate the solubility of nOctane in methanol at
25C. (Hint PiSats cancel.)
(a) 3E-2(b) 3E-3(c) 3E-4 (d) 3E-6
60
Day 58 LLE
58.1 LLE might exist for nHexane(1) furfural
(2) at 1.013 bars. The Margules 1-parameter is
A2.68, where GE/RTAx1x2. Estimate the
solubility (mole fraction) of nHexane in furfural
at 25C.
(a) 1E-1(b) 1E-2(c) 1E-3 (d) 1E-5
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Day 58 LLE
58.2 LLE might exist for nHexane(1) furfural
(2) at 1.013 bars. The Margules 1-parameter is
A2.68, where GE/RTAx1x2. Estimate the kij of
the ScHil model by matching the value for GE/RT
at x10.5 and 25C. The relevant values for
furfural areTc(K) Pc(MPa) w CP/R MW d r298 570.
0 5.60 0.370 86.00 96 11.5 1.17
(a) 0.05(b) 0.02(c) -0.02 (d)
-0.05
62
Day 58 LLE
58.3 LLE might exist for nHexane(1) furfural
(2) at 1.013 bars. The Margules 1-parameter is
A2.68, where GE/RTAx1x2. Estimate the
solubility (mole fraction) of nHexane in furfural
at 25C using the ScHil model tuned to this value
of A.
(a) 0.001(b) 0.04(c) 0.07 (d) 0.10
63
Day 58 LLE
58.4 Estimate the solubility (mole fraction) of
ethylBenzene in water at 25C using the
UNIFAC(LLE) model.
(a) 1E-1(b) 1E-2(c) 1E-3 (d) 1E-5
64
Last Day QQ3.5
QQ3.5.1 Estimate the solubility (mole fraction)
of p-xylene (dimethybenzene) in water at 25C
using the UNIFAC(LLE) model.
(a) 6E-1(b) 6E-2(c) 6E-3 (d) 6E-5
65
Last Day QQ3.5
QQ3.2 The Margules 1-parameter is A3.0, where
GE/RTAx1x2. Estimate the solubility (mole
fraction) of component 1 in component 2.
(a) 5E-1(b) 5E-2(c) 5E-3 (d) 5E-5
66
Qq3.5.3 Which of the following properly depicts
a maximum boiling azeotrope?
Last Day QQ3.5
67
Last Day QQ3.5
Qq3.5.4.___ Recall, eij (eii ejj )½ (1- kij
)1. Which (A or B) corresponds to kij gt 0?2.
Which corresponds to components liking each
other?3. Which corresponds to a higher fugacity
mixture?4. Which will give the highest bubble
point pressure?
68
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