Thermodynamics

Chapter 13 | 709REFERENCES AND SUGGESTED READING1. A. Bejan. Advanced Engineering Thermodynamics. 2nded. New York: Wiley Interscience, 1997.2. Y. A. Çengel, Y. Cerci, and B. Wood, “Second LawAnalysis of Separation Processes of Mixtures,” ASMEInternational Mechanical Engineering Congress andExposition, Nashville, Tennessee, 1999.3. Y. Cerci, Y. A. Çengel, and B. Wood, “The MinimumSeparation Work for Desalination Processes,” ASMEInternational Mechanical Engineering Congress andExposition, Nashville, Tennessee, 1999.4. J. P. Holman. Thermodynamics. 3rd ed. New York:McGraw-Hill, 1980.5. K. Wark, Jr. Advanced Thermodynamics for Engineers.New York: McGraw-Hill, 1995.PROBLEMS*Composition of Gas Mixtures13–1C What is the apparent gas constant for a gas mixture?Can it be larger than the largest gas constant in the mixture?13–2C Consider a mixture of two gases. Can the apparentmolar mass of this mixture be determined by simply takingthe arithmetic average of the molar masses of the individualgases? When will this be the case?13–3C What is the apparent molar mass for a gas mixture?Does the mass of every molecule in the mixture equal theapparent molar mass?13–4C Consider a mixture of several gases of identicalmasses. Will all the mass fractions be identical? How aboutthe mole fractions?13–5C The sum of the mole fractions for an ideal-gas mixtureis equal to 1. Is this also true for a real-gas mixture?13–6C What are mass and mole fractions?13–7C Using the definitions of mass and mole fractions,derive a relation between them.13–8C Somebody claims that the mass and mole fractionsfor a mixture of CO 2 and N 2 O gases are identical. Is thistrue? Why?13–9C Consider a mixture of two gases A and B. Show thatwhen the mass fractions mf A and mf B are known, the molefractions can be determined fromy A M BM A 11>mf A 12 M Bandy B 1 y Awhere M A and M B are the molar masses of A and B.*Problems designated by a “C” are concept questions, and studentsare encouraged to answer them all. Problems designated by an “E”are in English units, and the SI users can ignore them. Problemswith a CD-EES icon are solved using EES, and complete solutionstogether with parametric studies are included on the enclosed DVD.Problems with a computer-EES icon are comprehensive in nature,and are intended to be solved with a computer, preferably using theEES software that accompanies this text.13–10 The composition of moist air is given on a molarbasis to be 78 percent N 2 , 20 percent O 2 , and 2 percent watervapor. Determine the mass fractions of the constituents of air.13–11 A gas mixture has the following composition on amole basis: 60 percent N 2 and 40 percent CO 2 . Determine thegravimetric analysis of the mixture, its molar mass, and gasconstant.13–12 Repeat Prob. 13–11 by replacing N 2 by O 2 .13–13 A gas mixture consists of 5 kg of O 2 , 8 kg of N 2 ,and 10 kg of CO 2 . Determine (a) the mass fraction of eachcomponent, (b) the mole fraction of each component, and(c) the average molar mass and gas constant of the mixture.13–14 Determine the mole fractions of a gas mixture thatconsists of 75 percent CH 4 and 25 percent CO 2 by mass.Also, determine the gas constant of the mixture.13–15 A gas mixture consists of 8 kmol of H 2 and 2 kmol ofN 2 . Determine the mass of each gas and the apparent gas constantof the mixture. Answers: 16 kg, 56 kg, 1.155 kJ/kg · K13–16E A gas mixture consists of 5 lbmol of H 2 and4 lbmol of N 2 . Determine the mass of each gas and the apparentgas constant of the mixture.13–17 A gas mixture consists of 20 percent O 2 , 30 percentN 2 , and 50 percent CO 2 on mass basis. Determine the volumetricanalysis of the mixture and the apparent gas constant.P-v-T Behavior of Gas Mixtures13–18C Is a mixture of ideal gases also an ideal gas? Givean example.13–19C Express Dalton’s law of additive pressures. Does thislaw hold exactly for ideal-gas mixtures? How about nonidealgasmixtures?13–20C Express Amagat’s law of additive volumes. Does thislaw hold exactly for ideal-gas mixtures? How about nonidealgasmixtures?