HW7-2011 - How much heat per mole do we need? (Neglect any...

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ECH 152A, Fall 2011, Roland Faller Homework 7, November 7, 2011 This is a voluntary review homework for the 2nd Midterm. It will not be graded. Solutions will be online by Wednesday Nov 9. A reminder: Due to the Veteran’s Day holiday and the midterm there are no office hours of the instructor on Nov 11 and 14. There is instead a special 2 hour office hour on Nov 10 from 12-2 pm. As in a real exam, necessary data is in the Appendix 1. (From 2010 Midterm 2) A Stirling engine consists of two isothermal and two isochoric legs, i.e. we have a isochoric heating, an isothermal expansion, an isochoric cooling and an isothermal compression. (a) Plot it in a pV diagram. (b) Calculate its efficiency for an ideal gas in terms of the temperatures and the volumes. 2. (From 2007 Midterm 2) We produce chlorine based on 4HCl + O 2 2H 2 O + 2Cl 2 with a feed stream of (all percentages are molar ratios) 60% HCl, 36% oxy- gen and the rest nitrogen at 550 C. We convert 75% of the HCl isothermally.
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Unformatted text preview: How much heat per mole do we need? (Neglect any phase transitions in your calculations.) 3. (From 2010 Midterm 2) (a) Write down one version of the second law. (b) What is adiabatic? (c) Dene eciency for a heat engine. (d) Dene heat of formation. 4. (From 2009 Midterm 2) Assume a gas can be described by the following equation of state pV NRT = 1 + ap 2 + b p with a = 7 10-11 1 mole Pa 2 and b = 0 . 21 Pa mole . (a) Calculate the work required (for one mole at 300 K) to increase the pressure from 50 to 200 kpa. (b) Calculate the volumes for the initial and nal state of part (a). Appendix: H f (H 2 O, 298K) = -286 kJ/mol H f (HCl, 298K) = -92 kJ/mol The heat capacities can be expressed as c P R = A + BT + CT 2 + D T 2 with A 10 3 B K C DK 2 10 5 HCl 3.2 0.6 0.15 O 2 3.6 0.5-0.23 H 2 O 3.5 1.5 0.12 Cl 2 4.4 0.09-0.34 The gas constant is 8.314472 J/(mol*K)...
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HW7-2011 - How much heat per mole do we need? (Neglect any...

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