課程名稱︰化工熱力學
課程性質︰授課
課程教師︰陳延平
開課學院：化工系
開課系所︰化工系
考試日期（年月日）︰99/1/12
考試時限（分鐘）：10:20~12:10
是否需發放獎勵金：是
（如未明確表示，則不予發放）
試題 :
Chemical Engineering Thermodynamics
final examination ,January 12,2010
Problem 1(25%)
The Henry's law is used to calculate the low solubility of gas in a liquid .
For example , we can determine the amount of nitrogen dissolve in human bodily
fluid.
Suppose a diver has a body mass of 70 kg where 75% is water.His body temperature
-e is 37"C . The Henry's constant for nitrogen in water at 37"C is 1.005*10^5
atm . The diver was originally at a sea depth with air pressure of 6 atm .When
he comes to the surface of the sea, the pressure becomes 1 atm, The air is
always assumed to contain nitrogen with mole fraction of 0.79.
(1)Calculate the mass(gram)of nitrogen rejected from his body when he comes to
the surface.
(2)Will this amount of nitrogen rejected(in the unit of liters)cause a fatal
problem if you convert the answer in(1) into volume (liters) at the sea
surface condition(1bar and 298K)?
Problem 2(25%)
The activity coefficients for a binary mixture of components 1 and 2 at a
certain temperature are:
lnr1=x2^2[A12+2(A21-A12)*x1]
lnr2=x1^2[A21+2(A12-A21)*x2]
From some experimental study , it is found that this binary mixture has an
azeotrope at 86.67kPa with composition x1(az)=0.84.
The pure component vapor pressures at this temperature are P1(vp)=82.4 kPa
P2(vp)=37.3 kPa.
(1)Determine the activity coefficients r1 and r2 at the azeotropic point.
(2)Determine the activity coefficient model parameters:A12 and A21.
(3)Sketch the pllot of activity coefficients against composition x1. Indicate
the values of infinite dilution activity coefficients(r1(x1->0)and r2(x2->0))
on the plot.
Problem 3(25%)
The activity coefficients for a binary mixture of components 1 and 2 are:
lnr1 = a(1-x1)+b(1-x1)^2+d(1-x1)^3
lnr2 = Ax1+Bx1^2+Dx1^3
The activity coefficient is a partial molar property of G^E/RT.These partial
molar propeties are not independent, and they have to satisfy the Gibbs-Duhem
equation:
sigama(xidGi^E) = 0 at constant T and P
(1)Find out the relations between the model parameters:
a = A =0, D+d=0 , B = b + 1.5d
(2)The values are b =2 and d =4 for a specific binary mixture.
Calculate the molar Gibbs energy change on mixing(G/RT)for the composition of
x1 = 0.4.
Problem 4(25%)
(1)Components 1 and 2 have molecular weights of 100g/mol and 160g/mol respecti
-vely. At 300K and 1bar , the densities of components 1 and 2 are 2 and 3
g/cm^3, respectively.After mixing these two pure components with the compositi
-on x1 = 0.6 , we find the volume of mixture is 46.5cm^3/mol.Calculate the exc
-ess molar volume (cm^3/mol) of this mixture. Also , determine the residual
molar volume(cm^3/mol)of this mixture.
(2)There are two liquid phases that are brought into contact.Phase a has compo
-nents A and B ,and phase b contains components A an C. Component B and C are
immiscible . In the a phase ,component A has a mole fraction of 0.3 and activi
-ty coefficient of 1.5.In the b phase, component A has a mole fraction of 0.4
and activity coefficient of 2.0 .Upon putting these two phases are in contact,
will component A move from phase a to phase b? Why?
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