Chemical Thermodynamics (CHMS4208)
BSc, Chemistry - CHMS
Semester: Second Semester
Level: 400
Year: 2018
REPUBLIC OF CAMEROON REPUBLIQUE DU CAMEROUN
Peace-Work-Fatherland Paix-Travail-Patrie
THE UNIVERSITY OF BAMENDA UNIVERSITE DE BAMENDA
P.O. Box 39 Bambili
School/Faculty:FS Department: CHEMISTRY lecturer(s): NDIKONTAR
Course code: CHMS4208 Course title: CHEMICAL THERMODYNAMICS
Date: 11/07/2018hall:PBC03-PBC04Time: 11:00-14:00 (3 hours)
Instructions: Answer all questions. It is important to present your work in an orderly manner.
Useful data: R= 8.314J mol
-1
K
-1
= 1.987cal mol
-1
k
-1
; 1 atm = 760 torr = 1.013 bar
1. (6 mks). In a certain experiment designed to determine teh specific heat capacity of copper,
0.1Kg of the metal at 100
o
C was immersed in 200 cm
3
of water at 15
o
C in a thermally
insulated vessel of. After the mixture has reached equilibrium, the temperature is measured
to be 18.8
o
C.
(a) What approximation do you make because of the negligible thermal capacity of the
vessel?
(b) If the heat capacities of copper and of water are essentially constant over the range of
temperature concerned, calculate the specific heat capacity of copper.
(c) Does this experiment measure C
p
or C
v
? Would there be any difference between these
quantities for copper under the conditions of the experiment? Explain?
2. (9 mks). A vessel of 5.01 dm
3
containing nitrogen at a pressure of 5.03 atm is made to
communicate with another vessel of 4.02 dm
3
containing helium under a pressure of 4.07
atm at the same temperature as teh first. By assuming ideal gas behavior, calculate
a) the total pressure P at equilibrium,
b) the partial pressure P
i
of each constituent of the mixture, and
c) the change in entropy ∆ due to mixture.
3. (9 mks). The vapour pressure of liquid sodium in equilibrium with its vapour varies with
temperature according to the data below
By plotting these data approprately, determine
a) The normal boiling point of liquid sodium
b) The enthalpy of vaporisation, and
c) The change in entropy of vaporisation at the boiling point.
d) What would you do to the data above in order to determine the standard boiling point
of liquid sodium? How would this standard boiling point compare to your answer in a)
above?
4. (6 mks). Calculate the work and heat exchanged between the system and the sorroundings
for a reversible adn adiabattic compression of one mole of ideal monoatomic gas from a
pressure of 1.5atm at 500K to a pressure of 5.0 atm.
5. (6 mks). The solid-liquid phase diagram of water-nitric acid shows the formation of two
congruently melting compounds:HNO
3
.3
H
2
OAT
-18
O
C
and HNO
3
.3
H
2
O
at -38
o
C. The melting
point of HNO
3
is -41
o
C. Going across the diagram from H
2
O to HNO
3
, the eutectictemperature
P (atm)
1.32 x 10
-3
13.2 x 10
-3
132 x 10
-3
(
o
C)
439
549
701
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are -43, -42 and -66
o
C. Sketch the solid-liquid diagram. Label all areas. Sketch the cooling
curves for solutions of compositions x(HNO
3
) = 0.2 and 0.5.
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