King Saud University- College of Engineering- Chemical Eng.
Che 543 Advanced Chemical Engineering Thermodynamics
1st TERM 1431/1432H
Tutorial 5
Q1. 1.165 Kg moles of nitrogen and 0.465 kg moles of hydrogen are equilibrated in a
1m3 vessel at 450oC. At equilibrium 0.0845 kgmoles of ammonia is present. Determine
the amounts of nitrogen and hydrogen present and the partial pressures of all components
at equilibrium.
Q2 For the reaction
2H2(gas) + O2(gas) = 2H2O (gas)
The value of Kp at 1727oC is 1.55x107, partial pressures being measured in atmospheres.
Calculate ∆G0 and ∆G when two moles of hydrogen at 0.10 atmospheres react with
one mole of oxygen at 0.10 atmosphere to form water vapor at 1 atmosphere, the
temperature being 1727oC.
Q3.The process for production of ethanol is by the direct hydration of ethylene using phosphoric
acid catalyst. The temperature is around 600K.
C2H4(g) + H2O(g) = C2H5OH (g)
a) Use the Cp functions below to calculate Cp for the reactants
Cp(C2H5OH) = 19.9 +(20.95) 10-2 T – (10.37)10-5 T2 + (20.04) 10-9 T3
Cp(C2H4) = 3.5 +(15.63) 10-2 T – (8.339)10-5 T2 + (17.66) 10-9 T3
Cp(H2O) = 32.2 +(0.192) 10-2 T – (1.054)10-5 T2 + (3.594) 10-9 T3
o
b) Find ∆H for the reaction if H 298
(C2H5OH) = - 235.3 KJ/mol
o
H 298
(C2H4) = + 52.28 KJ/mol
c) Find
O
G298
for
the
o
H 298
(H2O) = - 241.8 KJ/mol
reaction
if
O
G298
(C2H5OH)g
=
-168.6KJ/mol
O
O
G298
(C2H4)g = +68.12KJ/mol G298
(H2O)g = -227.6KJ/mol
d) Obtain a relationship for GT0 in terms of constant and T terms
0
e) A company operating the process recommend T=572K, find G572
and K, the
equilibrium constant. Is this a small value, if so how is it the process can be worked
efficiently.