HW6-2011 - can depend on temperatures for a reversible...

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ECH 152A, Fall 2011, Roland Faller Homework 6, October 31, 2011 Due: November 7, Beginning of Lecture 1. (6 points) (a) Estimate Δ H f (298K) for the following at 25 C: Acetylene, n -Hexane, Styrene (b) Determine the standard heat of reaction for the following (25 C): N 2 (g)+3H 2 (g) 2NH 3 (g); C 2 H 4 (g)+H 2 O(l) C 2 H 5 OH(l) N 2 (g)+C 2 H 2 (g) 2HCN(g) 2. (6 points, This problem was on MT 2, 2008) We run the following reaction 2NH 3 + A O 2 B H 2 O + C NO 2 with a feed stream of (all percentages are molar ratios) 60% ammonia, 36% oxygen and the rest nitrogen at 400 C. (a) Determine A , B and C . (b) We now convert all oxygen isothermally. How much heat per mole feed do we need. (Neglect any phase transitions in your calculations.) 3. (6 points, This problem was on MT 2, 2007) (a) The Carnot engine consists of two isothermal and two adiabatic legs. Sketch it in the pV diagram. (b) How is efficiency for a heat engine defined in general? Explain why it only
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Unformatted text preview: can depend on temperatures for a reversible Carnot engine. (c) The efficiency of a ideally reversible Carnot engine is η = 1-T C T H . In some power plant the work is 25% of the released heat. Assume the fluid is heated to 2300 K and the plant is rated at 300 MW (pebble bed nuclear reactor). How much heat is required and released if the release temperature is 1300 K. How much below ideal efficiency are we? 4. (8 points, This is an ABET Outcome assessment ((a) an ability to apply knowledge of mathematics, science, and engineering) Problem. Please Indicate your Major on the solution) Obtain the heat of combustion of urea at a relevant temperature from an ap-propriate table. Based on that estimate the heat of formation of urea at 298 K, 368 K and 450 K. Give all your sources (Wikipedia is NOT reliable)....
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