THE UNIVERSITY OF BRITISH COLUMBIA
Department of Chemical and Biological Engineering
MID-TERM EXAMINATION (October 2020)
CHBE-346 ENGINEERING THERMODYNAMICS
Examiner: Prof. Savvas G. Hatzikiriakos
This is an open book exam. You are allowed to use your Textbook (hardcopy ONLY). Your desk
should be cleared of any electronic devices including laptops, phones, beepers, and other(s).
Time allotted: 1 hr 45 min (9.00 am to 10.40 am). Submit your work on Canvas by 11.00 am
(Canvas port closes exactly at 11pm – Unable to submit after 11:00 am). Answer both questions.
PROBLEM 1 (60%)
Assuming that the system ethyl methyl ketone (1)/toluene(2) at 50oC is described by the
Margules equation with A12=0.3681 and A21=0.2046, do the following:
(a) Calculate the bubble pressure at 50oC of the mixture with z1=0.3 and the composition of the first
bubble formed at that pressure. (10%).
(b) Calculate the dew pressure at 50oC of a mixture with z1=0.3 and the composition of the first
droplet formed at that pressure (20%).
(c) A mixture with z1=0.3 is flashed to 50oC at pressure such that a stream is received that contains
88% toluene by mol. Determine the pressure for this process and the %mol of toluene in the
other stream. Determine the percentage of feed exiting the flash drum as vapor (V/F) and that as
liquid (L/F) (20%).
(d) Sketch the phase diagram (P-xy in kPa) of this system at 50oC indicating all your relevant
calculations from parts (a), (b) and (c) (10%).
Given P1sat 36.1kPa and P2sat 12.3 kPa
PROBLEM 2 (40%)
The partial molar enthalpies of species 1 and 2 in a binary mixture at 25oC are given by
H1 100(1 0.08x22 ) and H 2 80(1 0.1x12 )
Where enthalpy is in kJ/mol
(a) Calculate the molar enthalpies of the pure components and explain how (5%)
(b) Calculate the partial molar enthalpies of the two components at infinite dilution and explain how
(5%)
(c) Determine the excess partial molar enthalpies of the two components as functions of the
composition and calculate their values at infinite dilution and explain how? (10%)
(d) Calculate the molar enthalpy of an equimolar solution (5%)
(e) Calculate the enthalpy change when the two components are mixed at constant temperature and
pressure to produce an equimolar solution (10%)
(f) Is this an endothermic or exothermic system? Is the system ideal or non-ideal-explain in
adequate detail? (5%)
This study source was downloaded by 100000899606070 from CourseHero.com on 09-27-2025 21:58:46 GMT -05:00
https://www.coursehero.com/file/71595186/MID-TERM-2020-CHBE-346pdf/
Department of Chemical and Biological Engineering
MID-TERM EXAMINATION (October 2020)
CHBE-346 ENGINEERING THERMODYNAMICS
Examiner: Prof. Savvas G. Hatzikiriakos
This is an open book exam. You are allowed to use your Textbook (hardcopy ONLY). Your desk
should be cleared of any electronic devices including laptops, phones, beepers, and other(s).
Time allotted: 1 hr 45 min (9.00 am to 10.40 am). Submit your work on Canvas by 11.00 am
(Canvas port closes exactly at 11pm – Unable to submit after 11:00 am). Answer both questions.
PROBLEM 1 (60%)
Assuming that the system ethyl methyl ketone (1)/toluene(2) at 50oC is described by the
Margules equation with A12=0.3681 and A21=0.2046, do the following:
(a) Calculate the bubble pressure at 50oC of the mixture with z1=0.3 and the composition of the first
bubble formed at that pressure. (10%).
(b) Calculate the dew pressure at 50oC of a mixture with z1=0.3 and the composition of the first
droplet formed at that pressure (20%).
(c) A mixture with z1=0.3 is flashed to 50oC at pressure such that a stream is received that contains
88% toluene by mol. Determine the pressure for this process and the %mol of toluene in the
other stream. Determine the percentage of feed exiting the flash drum as vapor (V/F) and that as
liquid (L/F) (20%).
(d) Sketch the phase diagram (P-xy in kPa) of this system at 50oC indicating all your relevant
calculations from parts (a), (b) and (c) (10%).
Given P1sat 36.1kPa and P2sat 12.3 kPa
PROBLEM 2 (40%)
The partial molar enthalpies of species 1 and 2 in a binary mixture at 25oC are given by
H1 100(1 0.08x22 ) and H 2 80(1 0.1x12 )
Where enthalpy is in kJ/mol
(a) Calculate the molar enthalpies of the pure components and explain how (5%)
(b) Calculate the partial molar enthalpies of the two components at infinite dilution and explain how
(5%)
(c) Determine the excess partial molar enthalpies of the two components as functions of the
composition and calculate their values at infinite dilution and explain how? (10%)
(d) Calculate the molar enthalpy of an equimolar solution (5%)
(e) Calculate the enthalpy change when the two components are mixed at constant temperature and
pressure to produce an equimolar solution (10%)
(f) Is this an endothermic or exothermic system? Is the system ideal or non-ideal-explain in
adequate detail? (5%)
This study source was downloaded by 100000899606070 from CourseHero.com on 09-27-2025 21:58:46 GMT -05:00
https://www.coursehero.com/file/71595186/MID-TERM-2020-CHBE-346pdf/
