Chemical Engineering Society
Council of Student Organizations
De La Salle University – Manila
SEPAPRO QUIZ#1 REVIEWER
Questionnaire:............................................................
I. Multiple Choice
(open handbook only for #’s 1-8)
1. At a given pressure, a liquid mixture of benzene and
toluene is in equilibrium with its vapour. The available
degree(s) of freedom is (are):
a. zero
b. 1
c. 2
d. 3
2. The temperature of the solution in a batch/differential
distillation process as distillation progresses at a
constant pressure is
a. Increasing
b. Decreasing
c. Remain constant
d. None of these
3. The relative volatility of A with respect to B in a mixture
of A and B is 3/2. What is the mole fraction of B in the
first droplet of liquid condensed from an equimolar
saturated vapor mixture of A and B?
a. 0.3
b. 0.4
c. 0.5
d. 0.6
4. An equimolar liquid mixture of species 1 and 2 is in
equilibrium with its vapour at 400K. At this
temperature, the vapor pressures of the species 1 and 2
are 180 KPa and 120 KPa respectively. Assuming
Raoult’s law is valid, the value of the mole fraction of
species 1 in the vapor phase is
a. 0.5
b. 0.6
c. 0.7
d. 0.8
5. A benzene-toluene mixture (56% by weight of benzene)
is maintained at 920C and 1 atm. The condition of this
mixture is a
a. Saturated liquid
b. Saturated vapor
c. Supersaturated vapor
d. Mixture of Liquid and vapor
6. If Ta and Tb are the boiling points of pure A and pure B
respectively and T is the boiling point of a nonhomogenous immiscible mixture of A and B, then
a. T < Ta and Tb
b. T > Ta and Tb
c. Ta < T < Tb
d. Ta > T > Tb
7. The ease or difficulty in separating components by
distillation is determined by the
a. Viscosity
b. Density
c. Mole Fraction
d. None of these
8. A mixture compound A and B forms a maximum boiling
azeotrope at x=0.8 at 1 atm total pressure. A solution of
this composition has a bubble point (TB) and a vapor of
the same composition has a dew point (TD). Then
a. Tb < Td
b. Tb = Td
c. Tb > Td
d. Cannot tell
9. The relative volatility of A with respect to B is 2. At what
concentration of A of the mixture of A and B is the slope
of the equilibrium line unity in a plot of y versus x?
a. 0.366
b. 0.414
c. 0.500
d. Never occur
10.
An ideal flash/equilibrium vaporization is carried
out with a binary mixture at constant temperature and
pressure. A process upset leads to an increase in the
mole fraction of the less volatile component in the feed.
The flash vessel continues to operate at the previous
temperature and pressure and still produces liquid and
vapor. After steady state is re-established,
a. The amount of liquid produced will decrease
b. The amount of vapor produced will decrease
c. The amount of liquid and vapor produced will
remain the same
d. The new equilibrium compositions of the
vapor and liquid products will be different
1
II. Problem Solving
Answers:…………............................................................
1.
I.
2.
3.
A mixture of 60 mole % A and 40 mol % B is subject to
flash distillation at a separator pressure of 1 atm. The
relative volatility of A with respect to B is constant 3.
What fraction of the feed must be vaporized to have
the composition of the vapor leaving the separator be
75 mol % A?
A batch/differential distillation operation is carried
out to separate a feed containing 100 moles of a
binary mixture A and B. The mole fraction of A I the
feed is 0.7. The distillation progresses until the mole
fraction of A in the residue decreases to 0.6. The
equilibrium curve in this composition range may be
linearized to y = 0.7353x + 0.3088 where x and y are
the mole fraction of the more volatile component A in
the liquid and vapor phrases respectively. Calculate
the number of moles of residue.
Geraniol (C10H18O) is an essential oil of commercial
value. It is conventionally purified by steam
distillation. A pilot scale unit is charged with 2 Kg of
crude geraniol containing a small amount of nonvolatile impurities. Live saturated steam at 1050C is
passed through the still at a fixed rate. Geraniol is
practically immiscible with water. Vapor pressure of
water at 1050C is passed through the still at a fixed
rate. Geraniol is practically immiscible with water.
Vapor pressure of water at 1050C is 1.211 bars and
that of geraniol is given by:
𝑙𝑛(𝑃𝑣 ) = 21.1 −
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
B
A
D
B
D
A
D
B
B
B
II.
1. 𝑓 = 0.4
2. 𝐿𝑓 = 48.015𝑚𝑜𝑙𝑒𝑠 𝐴
3. 𝑥 = 1.585 𝐾𝑔𝑚𝑜𝑙 𝑠𝑡𝑒𝑎𝑚
7217
𝑇
Where: 𝑃𝑣 is in mmHg and T is in degree K
Neglecting condensation of steam, what is the
amount of steam needed?
Goodluck sa exam! Kaya niyo yan :)
2