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1.3 What causes an azeotrope?

ConcepTests in Chemical Engineering Thermodynamics Note: Slides marked with JLF were adapted from the ConcepTests of John L. Falconer, U. Colorado. Cf. Chem. Eng. Ed. 2004,2007. Day1 Review. 1.3 What causes an azeotrope?. The components can’t be distilled.

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1.3 What causes an azeotrope?

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  1. ConcepTests in Chemical Engineering ThermodynamicsNote: Slides marked with JLF were adapted from the ConcepTests of John L. Falconer, U. Colorado. Cf. Chem. Eng. Ed. 2004,2007

  2. Day1 Review 1.3 What causes an azeotrope? • The components can’t be distilled. • The components have similar boiling temperatures. • The components like each other in the extreme. • The components dislike each other in the extreme.

  3. Day1 Review 1.4 What’s the difference between a chemist and a chemical engineer? • Engineers like numbers. • About 20k$/yr. • Engineers care more about profits. • Engineers ask, “How does it work?”

  4. Day2 Preview 1.1 What is temperature? • “Hotness.” • A measure of heat. • A measure of kinetic energy. • What a thermometer says.

  5. Day1 Review 1.2 The picture below represents hard spheres colliding in a planar box (like an air hockey table). Which represents the area of the box that should be used to compute density? • The blue area. • The area inside the green (and grey) bars. • None of the above.

  6. Day2 Review 2.1. Which of the following represents an ideal gas?

  7. Day2 Review 2.2 Which is characteristic of a liquid relative to a vapor? • Liquid molecules move slower. • Liquid has a higher pressure. • Liquid molecules collide more. • The liquid has more energy.

  8. Day2 Review 2.3 For water at 375C and 10 MPa, find the internal energy (kJ/kg). • 2596.9 • 2699.6 • 2766.0 • 2833.1

  9. Day2 Review 2.4 The outlet from a turbine consists of steam at 100C and an entropy (S) of 7 kJ/kg-K. What is its quality? • 5% • 10% • 90% • 95% • 100%

  10. Day1 Review 3.1 When running a turbine, you want to recover as much energy as work as possible. If the efficiency is, say, 75% then 25% of the possible work must be lost. The lost work must show up in the turbine outlet stream somehow, but how? • Its pressure is relatively higher. • Its velocity is relatively higher. • Its temperature is relatively higher. • Its enthalpy is relatively higher.

  11. Day3 Review 3.2 What causes the efficiency of a turbine to be less than 100%? • Reversibility. • Pressure gradient. • Disorder. • Stirring.

  12. Day4 begin 4.1 Two molecules are bouncing in 2D with molecular weight of 16g/mole. Their velocities (m/s) are given by:<555, -432>, < -555,432>. Estimate the temperature in the box (K). • 700 • 800 • 900 • 1000

  13. vacuum vacuum vacuum 1 kg 2 kg gas gas gas 4.2 In these piston/cylinders, when the red stop is slipped out, the gas expands, and the piston moves until it hits the black stops. Each system is adiabatic. Each starts at 10 atm and 25oC and are ideal gases. Which has the largest lost work?JLF* A B C

  14. A B 4.3 The curve represents an adiabatic reversibleprocess for an ideal gas. Which regions cannot bereached by an adiabatic irreversible process? JLF C. All regions canbe reached

  15. Day4 Preview 4.4 High pressure steam flows through an adiabatic turbine to steadily produce work. Which is the best energy balance for solving this problem? • Hin*min – Hout*mout + W = d(mU)/dt • DU = Q + W • DH = Q + W • DU = DPV + W + mDv2/2

  16. Day4 Preview 4.5 High pressure steam flows into a piston-cylinder to produce work. Which is the most appropriate energy balance for solving this problem? • Hin*min – Hout*mout + W = d(mU)/dt • DU = Q + W • DH = Q + W • DU = DPV + W + mDv2/2

  17. Day6 Preview 6.1 Steam at 200 bars and 600C flows through a valve and out to the atmosphere. What will be the temperature after the expansion? • 550 • 523 • 3539 • 3489

  18. Day6 Preview 6.2 A gas is filling a rigid tank from a supply line. Which of the following represents the most appropriate energy balance? • DH = Q + W • DU = Q + W • d(nU)=Hdn • DnU = HDn

  19. Day6 Preview 6.3 A gas is leaking from a rigid tank into the air. Which of the following represents the most appropriate energy balance? • DH = Q + W • DU = Q + W • d(nU)=Hdn • DnU = HDn

  20. Day6 Preview 6.4 An ideal gas (Cp=3.5R) is adiabatically and reversibly compressed in a steady state process from 25C and 1bar to 10bar. What is the exit temperature (C)? • 300 • 50 • 500 • 100

  21. Day6 Preview 6.5 A ideal gas (Cp=3.5R) is adiabatically and reversibly compressed in a steady state process from 25C and 1bar to 10bar. What is the work requirement (J/mol)? • 2000 • 8000 • 4000 • 9000

  22. Day7 Preview 7.1 Two exit streams leave a turbine. One stream is given, the other can be inferred from the throttle. The turbine produces 100kW. Estimate the heat loss (kW). • 0.5 • 5 • 15 • 50

  23. Day7 Preview 7.2 Which of the following represents the value for the following integral? • 1 • 2 • 4 • 8

  24. Day7 Preview 7.3 Which of the following represents the value for the following integral? • 5 • 50 • 500 • 5000

  25. Day7 Preview 7.4 (Ex2.15) An insulated tank initially contains 500 kg of steam and water at 2.0 MPa. Half of the tank volume is occupied by liquid and half by vapor. The temperature (C) of the tank initially is closest to: • 25 • 100 • 150 • 200

  26. Day7 Preview 7.5 Steam at 150 bars and 600 C passes through a heater expander and emerges at 100 bars and 700 C. There is no flow of work into or out of the heater-expander, but heat is supplied. Using the steam tables, compute the flow of heat (kJ/kg) into the heater expander per mole of steam. • 200 • 300 • 400 • 500

  27. Day7 Preview 7.6 Steam at 150 bars and 600 C passes through a heater expander. Compute the (dimensionless) value of [H(150,600)-H(1,600)]/RT for steam at the inlet conditions. • 0.3 • 0.03 • -0.3 • -0.03

  28. Day7 QikQiz QQ1.1.1 What is the relationship for the force vs. distance, F(r), between two molecules according to the Lennard-Jones potential model?

  29. Day7 QikQiz QQ1.1.2 Molecules A and B can be represented by the square-well potential. For molecule A,  = 0.4 nm and  = 20e-22 J. For molecule B,  = 0.8 nm and  = 10e-22 J. Which molecule would you expect to have the higher boiling temperature?

  30. Day7 QikQiz QQ1.1.3 Steam initially at 20 MPa, T = 366C, and H = 2421.6 kJ/kg is throttled to 1.0 MPa. What % of the expanded stream is liquid? • 80 • 60 • 40 • 20

  31. Day7 QikQiz QQ1.1.4 Write the most appropriate energy balance for the following: A compressor is filling the Goodyear blimp. System: the blimp and its contents • DU = Q + W • d(nU) = Hdn + W • D(nU) = HDn + Q + W • DH = Q + W

  32. Day8 Preview 8.1 An insulated tank initially contains 500 kg of steam and water at 2.0 MPa. Half of the tank volume is occupied by liquid and half by vapor. 25 kg of moisture free vapor is vented from the tank so that the pressure and temperature are always uniform throughout the tank. Analyze the situation carefully and calculate the final pressure in the tank. E-bal? • DU = Q + W • d(nU) = Hdn + W • D(nU) = HDn + W • DH = Q + W

  33. Day8 Preview 8.2 In an old-fashioned locomotive an insulated piston+ cylinder is connected through a valve to a steam supply line at 3MPa and 300°C. The back side of the piston is vented to the atmosphere at the right side of the cylinder. The volume of the cylinder is 70 liters. When the valve opens the piston is touching the left side of the cylinder. As the piston moves to the right it accomplishes 108 kJ of work before it touches the right side of the cylinder. Then, the cylinder contains 0.5 kg of steam and the temperature remains at 300°C. • DU = Q + W • d(nU) = Hdn + W • D(nU) = HDn + W • DH = Q + W

  34. Day8 Preview 8.3 Megan is half Kevin’s age. In six more years, she’ll be four-fifths Kevin’s age. In 10 years, she’ll be six-sevenths Kevin’s age. Neither is a teenager. How old is Megan now? • 1 • 2 • 3 • 4

  35. Day8 Preview 8.4 Identify the engineer based on the following: • This room is a mess! • Would it be too much to ask for you to put your sox in their drawers?! • I know my calculator is in here somewhere! • The entropy in this room is 50 MJ/mol-K!

  36. Day8 Preview 8.5 Two coins are tossed once each. If heads, the coin is placed in boxA. If tails, the coin is placed in boxB. What is the probability that one coin is in each box? • 0% • 10% • 25% • 50%

  37. Day8 Preview 8.6 Five coins are tossed once each. If heads, the coin is placed in boxA. If tails, the coin is placed in boxB. What is the probability that one coin is in boxA? • 10% • 15% • 20% • 25%

  38. Day9 Preview 9.1 Five coins are tossed once each. If heads, the coin is placed in boxA. If tails, the coin is placed in boxB. What is the probability that one coin is in boxA? • 10% • 15% • 20% • 25%

  39. Day9 Preview 9.2 Four coins are tossed once each. If heads, the coin is placed in boxA. If tails, the coin is placed in boxB. What is the probability that one coin is in boxA? • 10% • 15% • 20% • 25%

  40. Day9 Preview 9.3 Do not use a calculator to solve the following. Compute: log10(8000)-log10(4)-log10(2)= • 3 • 2 • 1 • 0

  41. Day9 Preview 9.4 Nitrogen at 300K and 10bar is adiabatically and reversibly expanded to 1bar. What is the final temperature (K)? • 150 • 200 • 250 • 300

  42. Day9 Preview 9.5 Nitrogen at 300K and 10bar is throttled to 1bar. What is the final temperature(K)? • 150 • 200 • 250 • 300

  43. Day9 Preview 9.6 Suppose two boxes but the one with NA particles is three times as large as the empty box. Then what is the change in entropy? • Rln(4/3) • Rln(3/4) • Rln(4/1) • Rln(1/4)

  44. Day10 Preview 10.1 Three moles of N2 at 2 bars and 300K are expanded into a box that is 33.33% larger. Then what is the DS? • Rln(4/3) • Rln(3/4) • 3Rln(4/3) • 3Rln(3/4)

  45. Day10 Preview 10.2 One mole of O2 at 2 bars and 300K is expanded into a box that is four times larger. Then what is the DS? • Rln(4/3) • Rln(3/4) • Rln(4/1) • Rln(1/4)

  46. Day10 Preview 10.3 One mole of O2 is mixed with 3 moles of N2 at 2 bars and 300K. Then what is the final pressure (bar)? • 2 • 0.5 • 0.25 • 1

  47. Day10 Preview 10.4 One mole of O2 is mixed with 3 moles of N2 at 2 bars and 300K. Then what is the DS? • Rln(4/3) • 3Rln(4/3) • Rln(4/1)+Rln(4/3) • Rln(4/1)+3Rln(4/3)

  48. Day10 Preview 10.5 One mole of O2 is mixed with 3 moles of N2 at 2 bars and 300K. Then what is the DS/R? • 0.33ln(4/3) + 0.67ln(1/3) • 0.25ln(0.25)+0.75ln(0.75) • -0.25ln(1/4)-0.75ln(3/4) • ln(4/1)+3ln(4/3)

  49. Day10 Preview 10.6 (Closed book) Estimate Cv/R for He. • 1.0 • 1.5 • 2.0 • 2.5

  50. Day10 Preview 10.7 (Closed book) Estimate Cv/R for N2. • 1.5 • 2.0 • 2.5 • 3.0

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