1. Fugacity Contributions by: John L. Falconer & Will Medlin Department of Chemical and Biological Engineering University of Colorado Boulder, CO 80309-0424 Supported by the National Science Foundation

2. Which of the following will increase the fugacity of a component, A? A.Convert from solid to liquid B.Convert from liquid to solid C.Decrease pressure D.Dilute with component B E.None of the above

3. What is the driving force for component A to move from liquid to vapor to reach equilibrium? A. Pressure B. Entropy C. Enthalpy D. Concentration E. Gibbs free energy Vapor y A Liquid x A

4. 0.1 mol/L 0.5 mol/L One component exists in two phases at the same temperature, but the phases are not in equilibrium. Which phase has the higher fugacity? A.α B.β C.Same fugacity in each phase. D.Not enough information. α phase phase

5. 0.005 mol/L 0.10 mol/L One component exists in two phases at the same temperature, but the phases are not in equilibrium. What is the direction of mass transfer? A.From α to β. B.From β to α. C.No mass transfer occurs. D.Cannot predict direction. α phase phase

6. H2OH2O A B H 2 O + EtOH Two identical flasks at 45°C are connected by a tube. Flask A contains water and flask B contains 50% more water plus it contains ethanol. As the system approaches equilibrium, _______________________. A.water moves from A to B B.ethanol moves from B to A C.water moves to B and ethanol moves to A D.both water and ethanol move to A E.there is no change in solution levels

7. H 2 O 40 ° C A B H 2 O 35 ° C Two identical flasks are connected by a tube. Flask A contains water at 40°C. Flask B contains 50% more water at 35°C. As the system approaches equilibrium, _______________. A.water moves from A to B B.water moves from B to A C.no change occurs

8. H 2 O 40 ° C A B H 2 O 40 ° C Two identical flasks are connected by a tube. Flask A contains water at 40°C. Flask B contains 50% more water at 40°C. As the system approaches equilibrium, _______________. A.water moves from A to B B.water moves from B to A C.no change occurs

9. H 2 O 40 ° C A B H 2 O 40 ° C + NaCl Two identical flasks contain water at 40°C and are connected by a tube. NaCl is added to flask B. As the system approaches equilibrium, ______________. A.water moves from A to B B.water moves from B to A C.no change in levels occur

10. H 2 O 45 ° C A B 98% H 2 O + 2% EtOH 55 ° C Two identical flasks are connected by a tube. Flask A contains water at 45°C. Flask B contains twice the volume of A but is a 98% H 2 O/ 2% ethanol mixture at 55°C. As the system approaches equilibrium, _______. A.water moves from A to B B.ethanol moves from B to A C.water moves to B and ethanol to A D.both water and ethanol move to A E.no change in levels occur

11. NaCl Solution 25 o C A B Pure H 2 O 22 o C Flask A contains a NaCl solution at 25°C in equilibrium with the pure water at 22°C in flask B. P H2O sat (25°C) = 3.2 kPa P H2O sat (22°C) = 2.6 kPa Estimate the fugacity of water in the NaCl solution. A.3.2 kPa B.2.6 kPa C.< 2.6 kPa D.> 3.2 kPa E.> 2.6 kPa

12. H 2 O 45 ° C A B 80% H 2 O 45 ° C + 20% NaCl Two flasks at 45°C are connected by a tube. Flask A contains H 2 O, and flask B contains the same amount of an 80/20 mixture of H 2 O and NaCl. After 5 hours, ________. A.Beaker A has more water B.Beaker B has more water C.The amounts of water do not change since they are at the same temperature D.All the salt moves to beaker A

13. H 2 O 45 ° C NaCl A B H 2 O 45 ° C NaCl + 5 g KCl Two flasks at 45°C are connected by a tube. Flask A contains water and NaCl. Flask B contains 50% more water and also contains NaCl. The system is at equilibrium. When 5 g of KCl is added to Flask B, _________________. A.water moves from B to A B.water moves from A to B C.KCl moves from B to A D.nothing changes

14. Adsorption concentrates a molecule on a surface from another phase. Consider hexane liquid and vapor. The hexane concentration in the zeolite pores is ____________. A.higher in A B.higher in B C.the same in both D.Insufficient information Porous zeolite crystals Vapor Liquid A Vapor B

15. Two systems have acetone/hexane in vapor-liquid equilibrium at the same temperature. Acetone is enriched in the vapor phase. Both molecules adsorb on the zeolite surface, where they have a higher concentration than in the gas phase. Which arrangement will have a higher concentration of acetone adsorbed on the zeolite crystals? A.Higher in A B.Higher in B C.The same in both D.Insufficient information Porous zeolite crystals Vapor 50/50 Liquid A 50/50 Vapor B

16. Two systems have acetone/hexane in vapor-liquid equilibrium at the same temperature. Acetone is enriched in the vapor phase. Both molecules adsorb on the zeolite surface, where they have a higher concentration than in the gas phase. Which arrangement will have a higher concentration of acetone adsorbed on the zeolite crystals? A.Higher in A B.Higher in B C.The same in both D.Insufficient information Porous zeolite crystals 50/50 Vapor Liquid A 50/50 Liquid Vapor B

17. As the pressure increases from point 1 to 2, which figure shows an area proportional to the change in Gibbs free energy? P V 1 2 P V 1 2 AB

18. Which plot represents f vs. P for an ideal gas? P f P f P f P f AB DC

19. For the H-x A diagram at 80°C, what is the maximum value of the partial molar enthalpy of component A at 80°C? A.50 cal/mol B.22 cal/mol C.85 cal/mol D.100 cal/mol E.0 cal/mol xAxA H (cal/mol) 00.51.0 100 50 0 100 50 0

20. An isotherm for a cubic equation of state is shown below. Which line corresponds to a vapor-liquid equilibrium? A B C D E Pressure n/V

21. When both vapor and liquid are present, the fugacity at x 1 = 0.1 will be ________ at x 1 = 0.3. A.greater than B.less than C.equal to the value 0.10.30.5 P

22. When both vapor and liquid are present, the fugacity at x 1 = 0.1 will be ________ at x 1 = 0.3, because ________. A.greater than; pressure is higher B.less than; mole fraction is lower C.less than; partial pressure is higher D.equal to the value; its at equilibrium. 0.10.30.5 P

23. A metal box of fixed volume contains CO 2 at a pressure of 2 bar. Through a valve you add CH 4 at a constant rate and at constant temperature. Which plot represents how CH 4 fugacity changes with time up to a total pressure of 20 bar? Assume ideal gases. E.None of the above. 2 bar Time 20 bar Time ABCD fugacity 0 bar

24. A metal box of fixed volume contains CO 2 at 2 bar pressure. Methane was added at a constant rate and at constant temperature. Which is the most likely plot of CH 4 fugacity vs. time up to a total pressure of 20 bar? Assume ideal gases. 2 bar Time 20 bar Time ABCD 10 bar

25. Liquid water is in equilibrium with water vapor and air. P tot = 1.2 bar P H 2 O = 0.1 bar The fugacity of water is about __________. A.0.1 bar. B.1.2 bar. C.1.00 (dimensionless). D.Cannot be determined.

26. The boiling point of water at 1 bar is 100°C. At 150°C the boiling point is 4.7 bar. The fugacity of water at 150°C and 100 bar is closer to ______ bar. A.1 B.5 C.50 D.100

27. When comparing steam at 100°C to water at 100°C, steam has a higher enthalpy, _______, and ________. A.higher entropy, higher Gibbs free energy B.higher entropy, the same Gibbs free energy C.the same entropy, the same Gibbs free energy D.lower entropy, lower Gibbs free energy

28. 1 kg of ice and 1 kg of liquid water are at equilibrium at 0°C. When liquid ethanol is added and the temperature is kept at 0 o C, _______________. A.some ethanol freezes B.some water freezes C.some ice melts D.all the ice melts E.all the ethanol freezes

29. Ethanol at 0°C is added to a ice-liquid water mixture at 0°C in an adiabatic container. The temperature of the mixture _______________. A.decreases B.increases C.remains the same

30. A water/ethanol mixture is at -5°C. You drop an ice cube that was also at -5°C into the liquid. What happens? A.Nothing happens, the system stays at -5°C B.Some ice melts C.All ice melts D.Some water freezes

31. Air is bubbled through a tank of water at 25 o C and atmospheric pressure. The solubility of O 2 in water is about 0.005 mol% at 25 o C. Estimate the fugacity of oxygen in the water. A.1 bar B.0.2 bar C.0.5 bar D.2 bar E.0.0005 bar

32. A pure-component fluid is at 10 bar and 350 K. The Peng-Robinson equation of state has three real roots: 1) V = 0.080 L/mol ; fugacity = 11 bar 2) V = 8 L/mol ; fugacity = 9 bar The fluid is a ____________. A.liquid B.gas C.2-phase mixture D.supercritical fluid

33. A pure-component fluid is at 10 bar and 350 K. The Peng-Robinson equation of state has three real roots: 1) density = 25 mol/L; fugacity = 11 bar 2) density = 0.2 mol/L; fugacity = 9 bar The fluid is a ____________. A.liquid B.gas C.2-phase mixture D.supercritical fluid

34. Boiling point of water: P sat = 1.0 bar; T sat = 100°C P sat = 4.7 bar; T sat = 150°C The fugacity of water at 150°C and 100 bar is closer to __________. A.1 bar B.5 bar C.50 bar D.100 bar

35. Which of the following will increase the fugacity of a component, A? A.Convert from solid to liquid B.Convert from liquid to solid C.Decrease pressure D.Dilute with component B E.None of the above

36. If you were to boil water on a stove in a small room for an hour, the fugacity of the ______________. A.liquid increases B.water vapor increases C.liquid decreases D.water vapor decreases E.water stays the same in the vapor H2OH2O

37. Soda (liquid water with a low concentration of dissolved CO 2 ) at 0°C is compressed to 5 bar so only a liquid phase remains. In the liquid phase, the fugacity of ___________. A.water is higher B.CO 2 is higher C.water and CO 2 are the same

38. A can of soda at 0°C contains liquid water with a low concentration of dissolved CO 2. If the CO 2 pressure in the can is slightly above 1 bar, which has a higher fugacity in the liquid phase? A.Water B.CO 2 C.Fugacities of water and CO 2 are equal

39. When salt is added to pure water, what happens to the fugacity of the water? A.increases B.decreases C.stays the same

40. Pure NaCl was added to pure water until the water was saturated and the excess salt settled to the bottom of the container. What happened to the fugacity of the salt? A.Increased B.Decreased C.Did not change

41. Compared to the fugacity of pure water, the fugacity of water in a saline solution will be _________. A.higher B.lower C.the same

42. Pure NaCl was added to pure water until the water was saturated and the excess salt settled to the bottom of the container. The fugacity of the dissolved salt is __________ the fugacity of the pure NaCl. A.higher B.lower C.the same as

43. A liquid containing 60 mol% salt and 40 mol% water is in equilibrium with water vapor at 0.5 bar. Which species has the higher fugacity in the liquid? A.Salt B.Water C.Their fugacities are equal D.Need more information

44. A sealed container of water is at high enough pressure so that no vapor is present. The water contains 0.2 mol% salt and 0.2 mol% CO 2. Which component has the highest fugacity? A.Water B.CO 2 C.Salt D.Same for all

45. In a bubble pressure calculation using a EOS, the mole fractions of liquid are known, and the mole fractions of vapor must be calculated by iteration by guessing the pressure. After the first iteration,  y i > 1. For the next iteration, _______________. A.raise the pressure B.lower the pressure C.keep the pressure the same but change the composition

46. A EOS spreadsheet is used to calculate VLE for a binary mixture (x 1 = 0.9) with a non-ideal liquid phase and a non- ideal gas. Which statement about the fugacity coefficients is most likely to be correct?

47. Which of the following statements is NOT true at an azeotrope? A.x A = y A B.x A = x B C. D. E.None of the above

48. A.x 2  2 P B.x 2  2 L P C.x 2  2 L P sat D.x 2  2 P sat E.None of the above

49. Which of the following statements is NOT true at an azeotrope? A.x A = y A B. C. D. E.None of the above