课程名称︰化工热力学 课程性质︰授课 课程教师︰陈延平 开课学院：化工系 开课系所︰化工系 考试日期（年月日）︰99/1/12 考试时限（分钟）：10:20~12:10 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : 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? --

※ 发信站: 批踢踢实业坊(ptt.cc) ◆ From: 140.112.253.77