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Thermodynamics 2

Jahara Ca単as
Jahara Ca単as

The document contains 100 multiple choice questions related to thermodynamics II concepts including: - Phase changes and properties at triple points - Latent heats of vaporization and sublimation - Equations of state for gases including ideal gas, van der Waals, and virial - Critical properties and compressibility factors - Properties and processes involving steam including Joule-Thomson expansion - Chemical potentials and multi-component systems The questions cover a wide range of thermodynamics topics and concepts at an intermediate or advanced level.

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Thermodynamics II http://unitoperation.com/Thermo/Thermo2.htm Thermodynamics II 51. In the P-T diagram at triple point which of the following lines has the highest s (a) S L (b) L V 52. At the triple point of iodine (112.9属C and 11.57 kPa) the heat of fusion is 15.38 kJ/mol while the heat of sublimation is 59.8 kJ/mol. What is the latent heat of vaporization (kJ/mol)? (a) 44.5 (b) 75.1 53. For estimating the thermodynamic properties of ethane at 10 atm pressure which of the following equations of state would you recommend? (a) Ideal gas (b) van der Waal (c) Peng Robinson. (d) None of the above. 54. The law of corresponding states is that all fluids at (a) Same critical temperature and pressure will have the same critical volume (b) Same reduced temperature and pressure will have the same reduced volume (c) Same temperature and pressure will have the same specific volume (d) None of these 55A. Refer to the diagram : Indicate the state of the substance as Liquid(A) , ABDC Gas(B), Liquid in equilibrium with vapour(C), Superheated liquid((D) 55B. Refer to the diagram : For any point on the isotherm T5, which Of the following conditions is true? _ 56. Match the following equation of state BADC (i) z = 1 1 of 6 3/2/2012 7:08 PM
Thermodynamics II http://unitoperation.com/Thermo/Thermo2.htm (A) van-der waal (B) ideal gas (C) Redlich-Kwong (D) Virial 57. Which of the following is the Virial equation of state? (c) both a and (b) (d) neither a nor b B,C,D,B,C,D are the temperature dependent coefficients 58. Compressibility factor (Z) of an ideal gas is (a) = 1 at all temperature and pressure. (b) > 1 at all temperature and pressure. (c) < 1 at all temperature and pressure. (d) = 0 at all temperature and pressure. 59. The compressibility factor of a gas is equal to (a) ratio for pressure of a real gas to its vapour pressure at the same temperature (b) ratio of pressure of a real gas its critical pressure (c) ratio of molar volume of real gas to that of an ideal gas at the same temperature and pressure 60. Critical pressure of a substance is defined as (a) the pressure at which saturated liquid and vapour are in equilibrium (b) the pressure at which an azeotrope is formed when mixed with steam (c) the pressure above which the state of a substance may not be distinguished between liquid and vapour 61. At the critical point which of the following criteria is not valid? (a) TL = Tv (b) gL = gv (c) sL = sv (d) none of the above 62. Critical compressibility factor of a real gas is the value of compressibility factor at (a) Critical temperature and pressure (TC, PC). (b) When the compressibility factor becomes unity (c) When the compressibility factor becomes infinite (d) None of these. 63. Critical compressibility factor for permanent gases (N2, O2, etc) is approximately equal to (a) 0.28 (b) 0.35 (c) 1 (d) None of these. 64. At a reduced temperature of 1.10 and reduced pressure of 2.0 the compressibility factor for ethane is 0.42. What is the value compressibility factor for methane at the same reduced temperature and pressure ? (a) < 0.42 (b) 0.42 (c) > 0.42 (d) Need additional data. 2 of 6 3/2/2012 7:08 PM
Thermodynamics II http://unitoperation.com/Thermo/Thermo2.htm 65. The value of compressibility factor (Z) is always less than or equal to unity. (a) True. (b) False. 66. The critical compressibility factor predicted by the van-der-Waal equation of state will be (a) Same for all gases and is equal to unity (b) Same for all gases but not equal to unity (c) Different for different gases but is always greater than zero and less than unity (d) Different for different gases , actual value depends on the values of a and b (van-der Waals constants) 67. The cubic equation of state can be represented as z3 + aZ2 + bZ + g = 0, where z is the compressibility factor. For CH4 at one particular temperature and pressure, cubic equation of state has one real root and two imaginary roots, therefore the state of the substance is (a) Mixture of liquid and vapor (b) Either liquid or vapor but not a mixture (c) Impossible to have imaginary roots for a physically meaningful state of the substance (d) liquid 68. The P-v isotherm of a real gas goes through an inflexion at the (a) Critical pressure (b) Vapor pressure of the liquid (c) triple point 69. At the critical point (c) gliquid = gvapour (d) all of the above 70. Van-der Waals equation of state improved over the ideal gas equation of state with the following assumptions (a) infinitesimal molecular volume (b) no inter molecular force (c) both (a) and (b) (d) none of the above. 71. The ideal gas equation of state can predict the transition from the liquid state to vapor state of a substance (a) true (b) false 72. The critical compressibility factor predicted by the van-der equation of state is (a) 1.0 (b) 0.375 (c) 0.27 (d) none of the above. 73. The critical compressibility factor predicted by the ideal gas equation of state is (a) 1.0 (b) 0.375 (c) 0 (d) none of the above. 3 of 6 3/2/2012 7:08 PM
Thermodynamics II http://unitoperation.com/Thermo/Thermo2.htm 74. Critical compressibility factor for most real gases vary between (a) 0.23- 0.31 (b) 0.37 0.72 (c) 0.15 0.21 75. The critical compressibility factor value for water is (a) 0.23 (b) 0.35 (c) 1.0 (d) 0 76. Z(Tr = 1.20, Pr = 2.0) for N2 = 0.6. What would be the value of Z(Tr = 1.20, Pr = 2.0) O2? (a) >0.6 (b) <0.6 (c) =0.6 (d) Need additional data. For the following problems use the Steam Table 77. When saturated liquid water is heated to form saturated steam at 101.3 kPa which of the following is TRUE? (a) h = 0 (b) g = 0 (c) s = 0 (d) u = 0 78. Medium pressure steam is (a) 0-5 psig (b) 5-15 psig (c) > 15 psig. 79. In a piston cylinder apparatus, saturated steam at 1 atm is compressed to 5 atm, saturation temperature (a) T 152属(C) (b) T = 56属C (c) T = 400属 C (d) T = 98属 C 80. Steam at 1 atm. has an entropy = 6.619 kJ / kg.K. This steam is (a) Saturated steam. (b) Super heated steam. (c) Wet steam. (d) None of these. 81. At 1 atm pressure the enthalpy of evaporation of steam (DH) is 2258 kJ/kg . At P = 5 atm, T = 151.58属 C, DH (kJ/kg) is (a) < 2258 (b) > 2258 (c) =2258 (d) cannot be predicted. 82. For saturated steam at 1 atm, Ts = 100属 C the entropy of evaporation of steam (DS) is 6.0568 kJ/kg. Therefore, for saturated steam at 5 atm, Ts = 151.58属 C, DS is (a) 4.9606 (b) 6.5029 (c) 6.0568 (d) cannot be predicted 83. For saturated steam at 10 atm, TS = 179.91属 C, hsteam = 2778.1 kJ/kg.. If this steam is superheated to 500属C in a furnace at constant pressure, hsteam (kJ/kg) (a) 3478.5 (b) 2606.4 (c) 2778.1 (d) can not be predicted 84. Steam at 400 bar and 500属 C is throttled through an adiabatic pressure relief valve to atmospheric pressure. What is the temperature of steam after expansion? (a) 600属C (b) 212属C (c) 350属C (d) can not be predicted. 85. 98% quality of wet steam means 4 of 6 3/2/2012 7:08 PM
Thermodynamics II http://unitoperation.com/Thermo/Thermo2.htm (a) 0.02 kg water/kg steam-water mixture (b) 0.98 kg water/kg steam-water-mixture (c) 0.02 kg steam/kg steam-water mixture (d) 0.98 kg water/kg of steam. 86. Steam at 500 bar and 600 0C undergoes J-T expansion to 1 atm. What would be the temperature of steam after expansion ? Assume steam to be an ideal gas . (a) < 600 0C (b) 600 0C (c) > 600 0C 87. The enthalpy (kJ/kg) of steam at 400 bar and 500 0C is (a) 536 (b) 3900 (c) 2900 (d) 5300 88. The temperature (0C) of saturated steam at 5 bar is (a) 253.2 (b) 151.8 (c) 102.7 (d) need more data. 89. The enthalpy of steam (kJ/kg) at 10 atm and a degree of super heat of 320 0C is (a) 3478.5 (b) 2606.4 (c) 2778.1 (d) 433.3 90. Steam at 400 bar and 500 0C is (a) saturated (b) super heated (c) wet (d) none of the above. 91. For pure benzene vapor how many state variables must be defined for complete thermodynamic definition of the system? (a) 1(pressure or temperature) (b) 2(pressure and temperature) (c) 3(pressure, temperature and specific enthalpy) 92. Compressed air at a high pressure is steadily and continuously exhausted through a pressure reducing value (Joule- Thomson Expansion). The J-T expansion is an ------------ process (a) Isenthalpic (b) Isothermal (c) Isobaric (d) isochoric 93. For an ideal gas , the Joule Thompson coefficient is always (a) > 0 (b) < 0 (c) = 0 (d) Depends on upstream and down stream pressure. 94. The Joule Thompson expansion coefficient (m) is defined as _ 95. For an ideal gas, Joule Thompson expansion would always result (a) Increase in temperature (b) Decrease in temperature (c) Temperature remains unchanged 96. An ideal gas at 35 bar , 230 0C is throttled adiabatically to 5 bar. What is the change in specific entropy 5 of 6 3/2/2012 7:08 PM
Thermodynamics II http://unitoperation.com/Thermo/Thermo2.htm (J/mol.K) ? (a) 0 (b) 32.39 (c) 0.587 (d) 103.77 97. A steady stream containing 2% NaOH solution is entering a closed vessel. The overall mass balance equation is (a) M ( mass of liquid inside the vessel) is constant (b) (c) 98. Chemical potential is an (a) Extensive property. (b) Intensive property. 99. For a multi component system, chemical potential is equivalent to (a) Molal concentration difference. (b) Molar free energy of the pure compounds. (c) Partial molar free energy. (d) Change in molar free energy due to phase change. 100. The chemical potential of a species is an ideal solution depends on (a) Temperature. (b) Pressure. (c) Composition of solution (d) All of these. 6 of 6 3/2/2012 7:08 PM
http://unitoperation.com/Thermo/MarksThermo2.html Therodynamics II Attempted: Correct: Percent: 51) (a) 52) (a) 53) (a) (b) (c) 54) (a) (b) 55Ai) (a) 55Aii) (b) 55Aiii) (a) (d) 55Aiv) (b) (c) 55B) (a) 56i) (b) 56ii) (a) (b) 56iii) (a) (d) 56iv) (a) (c) 57) (a) (c) 58) (a) 59) (b) (c) 60) (b) (c) 61) (a) (d) 62) (a) 63) (a) (b) 64) (a) (b) 1 of 3 3/2/2012 7:08 PM
http://unitoperation.com/Thermo/MarksThermo2.html 65) (a) (b) 66) (b) 67) (a) (b) 68) (a) (b) 69) (a) (d) 70) (b) (c) 71) (b) 72) (a) (b) 73) (a) (b) 74) (a) 75) (a) (b) 76) (a) (c) 77) (a) (b) 78) (b) 79) (a) (b) 80) (a) (c) 81) (a) (b) 82) (a) 83) (a) (b) 84) (a) (b) 85) (a) 86) (a) (b) 87) (b) (c) 88) (b) 89) (a) (b) 2 of 3 3/2/2012 7:08 PM
http://unitoperation.com/Thermo/MarksThermo2.html 90) (a) (b) 91) (b) 92) (a) (b) 93) (b) (c) 94) (a) (b) 95) (a) (c) 96) (a) (d) 97) (b) 98) (b) 99) (b) (c) 100 ) (a) (d) 3 of 3 3/2/2012 7:08 PM

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Thermodynamics 2

  • 1. Thermodynamics II http://unitoperation.com/Thermo/Thermo2.htm Thermodynamics II 51. In the P-T diagram at triple point which of the following lines has the highest s (a) S L (b) L V 52. At the triple point of iodine (112.9属C and 11.57 kPa) the heat of fusion is 15.38 kJ/mol while the heat of sublimation is 59.8 kJ/mol. What is the latent heat of vaporization (kJ/mol)? (a) 44.5 (b) 75.1 53. For estimating the thermodynamic properties of ethane at 10 atm pressure which of the following equations of state would you recommend? (a) Ideal gas (b) van der Waal (c) Peng Robinson. (d) None of the above. 54. The law of corresponding states is that all fluids at (a) Same critical temperature and pressure will have the same critical volume (b) Same reduced temperature and pressure will have the same reduced volume (c) Same temperature and pressure will have the same specific volume (d) None of these 55A. Refer to the diagram : Indicate the state of the substance as Liquid(A) , ABDC Gas(B), Liquid in equilibrium with vapour(C), Superheated liquid((D) 55B. Refer to the diagram : For any point on the isotherm T5, which Of the following conditions is true? _ 56. Match the following equation of state BADC (i) z = 1 1 of 6 3/2/2012 7:08 PM
  • 2. Thermodynamics II http://unitoperation.com/Thermo/Thermo2.htm (A) van-der waal (B) ideal gas (C) Redlich-Kwong (D) Virial 57. Which of the following is the Virial equation of state? (c) both a and (b) (d) neither a nor b B,C,D,B,C,D are the temperature dependent coefficients 58. Compressibility factor (Z) of an ideal gas is (a) = 1 at all temperature and pressure. (b) > 1 at all temperature and pressure. (c) < 1 at all temperature and pressure. (d) = 0 at all temperature and pressure. 59. The compressibility factor of a gas is equal to (a) ratio for pressure of a real gas to its vapour pressure at the same temperature (b) ratio of pressure of a real gas its critical pressure (c) ratio of molar volume of real gas to that of an ideal gas at the same temperature and pressure 60. Critical pressure of a substance is defined as (a) the pressure at which saturated liquid and vapour are in equilibrium (b) the pressure at which an azeotrope is formed when mixed with steam (c) the pressure above which the state of a substance may not be distinguished between liquid and vapour 61. At the critical point which of the following criteria is not valid? (a) TL = Tv (b) gL = gv (c) sL = sv (d) none of the above 62. Critical compressibility factor of a real gas is the value of compressibility factor at (a) Critical temperature and pressure (TC, PC). (b) When the compressibility factor becomes unity (c) When the compressibility factor becomes infinite (d) None of these. 63. Critical compressibility factor for permanent gases (N2, O2, etc) is approximately equal to (a) 0.28 (b) 0.35 (c) 1 (d) None of these. 64. At a reduced temperature of 1.10 and reduced pressure of 2.0 the compressibility factor for ethane is 0.42. What is the value compressibility factor for methane at the same reduced temperature and pressure ? (a) < 0.42 (b) 0.42 (c) > 0.42 (d) Need additional data. 2 of 6 3/2/2012 7:08 PM
  • 3. Thermodynamics II http://unitoperation.com/Thermo/Thermo2.htm 65. The value of compressibility factor (Z) is always less than or equal to unity. (a) True. (b) False. 66. The critical compressibility factor predicted by the van-der-Waal equation of state will be (a) Same for all gases and is equal to unity (b) Same for all gases but not equal to unity (c) Different for different gases but is always greater than zero and less than unity (d) Different for different gases , actual value depends on the values of a and b (van-der Waals constants) 67. The cubic equation of state can be represented as z3 + aZ2 + bZ + g = 0, where z is the compressibility factor. For CH4 at one particular temperature and pressure, cubic equation of state has one real root and two imaginary roots, therefore the state of the substance is (a) Mixture of liquid and vapor (b) Either liquid or vapor but not a mixture (c) Impossible to have imaginary roots for a physically meaningful state of the substance (d) liquid 68. The P-v isotherm of a real gas goes through an inflexion at the (a) Critical pressure (b) Vapor pressure of the liquid (c) triple point 69. At the critical point (c) gliquid = gvapour (d) all of the above 70. Van-der Waals equation of state improved over the ideal gas equation of state with the following assumptions (a) infinitesimal molecular volume (b) no inter molecular force (c) both (a) and (b) (d) none of the above. 71. The ideal gas equation of state can predict the transition from the liquid state to vapor state of a substance (a) true (b) false 72. The critical compressibility factor predicted by the van-der equation of state is (a) 1.0 (b) 0.375 (c) 0.27 (d) none of the above. 73. The critical compressibility factor predicted by the ideal gas equation of state is (a) 1.0 (b) 0.375 (c) 0 (d) none of the above. 3 of 6 3/2/2012 7:08 PM
  • 4. Thermodynamics II http://unitoperation.com/Thermo/Thermo2.htm 74. Critical compressibility factor for most real gases vary between (a) 0.23- 0.31 (b) 0.37 0.72 (c) 0.15 0.21 75. The critical compressibility factor value for water is (a) 0.23 (b) 0.35 (c) 1.0 (d) 0 76. Z(Tr = 1.20, Pr = 2.0) for N2 = 0.6. What would be the value of Z(Tr = 1.20, Pr = 2.0) O2? (a) >0.6 (b) <0.6 (c) =0.6 (d) Need additional data. For the following problems use the Steam Table 77. When saturated liquid water is heated to form saturated steam at 101.3 kPa which of the following is TRUE? (a) h = 0 (b) g = 0 (c) s = 0 (d) u = 0 78. Medium pressure steam is (a) 0-5 psig (b) 5-15 psig (c) > 15 psig. 79. In a piston cylinder apparatus, saturated steam at 1 atm is compressed to 5 atm, saturation temperature (a) T 152属(C) (b) T = 56属C (c) T = 400属 C (d) T = 98属 C 80. Steam at 1 atm. has an entropy = 6.619 kJ / kg.K. This steam is (a) Saturated steam. (b) Super heated steam. (c) Wet steam. (d) None of these. 81. At 1 atm pressure the enthalpy of evaporation of steam (DH) is 2258 kJ/kg . At P = 5 atm, T = 151.58属 C, DH (kJ/kg) is (a) < 2258 (b) > 2258 (c) =2258 (d) cannot be predicted. 82. For saturated steam at 1 atm, Ts = 100属 C the entropy of evaporation of steam (DS) is 6.0568 kJ/kg. Therefore, for saturated steam at 5 atm, Ts = 151.58属 C, DS is (a) 4.9606 (b) 6.5029 (c) 6.0568 (d) cannot be predicted 83. For saturated steam at 10 atm, TS = 179.91属 C, hsteam = 2778.1 kJ/kg.. If this steam is superheated to 500属C in a furnace at constant pressure, hsteam (kJ/kg) (a) 3478.5 (b) 2606.4 (c) 2778.1 (d) can not be predicted 84. Steam at 400 bar and 500属 C is throttled through an adiabatic pressure relief valve to atmospheric pressure. What is the temperature of steam after expansion? (a) 600属C (b) 212属C (c) 350属C (d) can not be predicted. 85. 98% quality of wet steam means 4 of 6 3/2/2012 7:08 PM
  • 5. Thermodynamics II http://unitoperation.com/Thermo/Thermo2.htm (a) 0.02 kg water/kg steam-water mixture (b) 0.98 kg water/kg steam-water-mixture (c) 0.02 kg steam/kg steam-water mixture (d) 0.98 kg water/kg of steam. 86. Steam at 500 bar and 600 0C undergoes J-T expansion to 1 atm. What would be the temperature of steam after expansion ? Assume steam to be an ideal gas . (a) < 600 0C (b) 600 0C (c) > 600 0C 87. The enthalpy (kJ/kg) of steam at 400 bar and 500 0C is (a) 536 (b) 3900 (c) 2900 (d) 5300 88. The temperature (0C) of saturated steam at 5 bar is (a) 253.2 (b) 151.8 (c) 102.7 (d) need more data. 89. The enthalpy of steam (kJ/kg) at 10 atm and a degree of super heat of 320 0C is (a) 3478.5 (b) 2606.4 (c) 2778.1 (d) 433.3 90. Steam at 400 bar and 500 0C is (a) saturated (b) super heated (c) wet (d) none of the above. 91. For pure benzene vapor how many state variables must be defined for complete thermodynamic definition of the system? (a) 1(pressure or temperature) (b) 2(pressure and temperature) (c) 3(pressure, temperature and specific enthalpy) 92. Compressed air at a high pressure is steadily and continuously exhausted through a pressure reducing value (Joule- Thomson Expansion). The J-T expansion is an ------------ process (a) Isenthalpic (b) Isothermal (c) Isobaric (d) isochoric 93. For an ideal gas , the Joule Thompson coefficient is always (a) > 0 (b) < 0 (c) = 0 (d) Depends on upstream and down stream pressure. 94. The Joule Thompson expansion coefficient (m) is defined as _ 95. For an ideal gas, Joule Thompson expansion would always result (a) Increase in temperature (b) Decrease in temperature (c) Temperature remains unchanged 96. An ideal gas at 35 bar , 230 0C is throttled adiabatically to 5 bar. What is the change in specific entropy 5 of 6 3/2/2012 7:08 PM
  • 6. Thermodynamics II http://unitoperation.com/Thermo/Thermo2.htm (J/mol.K) ? (a) 0 (b) 32.39 (c) 0.587 (d) 103.77 97. A steady stream containing 2% NaOH solution is entering a closed vessel. The overall mass balance equation is (a) M ( mass of liquid inside the vessel) is constant (b) (c) 98. Chemical potential is an (a) Extensive property. (b) Intensive property. 99. For a multi component system, chemical potential is equivalent to (a) Molal concentration difference. (b) Molar free energy of the pure compounds. (c) Partial molar free energy. (d) Change in molar free energy due to phase change. 100. The chemical potential of a species is an ideal solution depends on (a) Temperature. (b) Pressure. (c) Composition of solution (d) All of these. 6 of 6 3/2/2012 7:08 PM
  • 7. http://unitoperation.com/Thermo/MarksThermo2.html Therodynamics II Attempted: Correct: Percent: 51) (a) 52) (a) 53) (a) (b) (c) 54) (a) (b) 55Ai) (a) 55Aii) (b) 55Aiii) (a) (d) 55Aiv) (b) (c) 55B) (a) 56i) (b) 56ii) (a) (b) 56iii) (a) (d) 56iv) (a) (c) 57) (a) (c) 58) (a) 59) (b) (c) 60) (b) (c) 61) (a) (d) 62) (a) 63) (a) (b) 64) (a) (b) 1 of 3 3/2/2012 7:08 PM
  • 8. http://unitoperation.com/Thermo/MarksThermo2.html 65) (a) (b) 66) (b) 67) (a) (b) 68) (a) (b) 69) (a) (d) 70) (b) (c) 71) (b) 72) (a) (b) 73) (a) (b) 74) (a) 75) (a) (b) 76) (a) (c) 77) (a) (b) 78) (b) 79) (a) (b) 80) (a) (c) 81) (a) (b) 82) (a) 83) (a) (b) 84) (a) (b) 85) (a) 86) (a) (b) 87) (b) (c) 88) (b) 89) (a) (b) 2 of 3 3/2/2012 7:08 PM
  • 9. http://unitoperation.com/Thermo/MarksThermo2.html 90) (a) (b) 91) (b) 92) (a) (b) 93) (b) (c) 94) (a) (b) 95) (a) (c) 96) (a) (d) 97) (b) 98) (b) 99) (b) (c) 100 ) (a) (d) 3 of 3 3/2/2012 7:08 PM