# PS7F07 - necessarily to scale for NH 3 It useful to think...

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Chemistry 391 Fall 2007 Problem Set 7 (Due, Monday October 29) 1. Consider the equilibrium C 2 H 6 ( g ) C 2 H 4 ( g ) + H 2 ( g ). At 1000 K and a constant total pressure of 1 bar, C 2 H 6 ( g ) is introduced into a reaction vessel. At equilibrium, the composition of the mixture in mole percent is H 2 ( g ): 26%, C 2 H 4 ( g ): 26%, and C 2 H 6 ( g ): 48%. a. Calculate K P at 1000 K. b. If reaction H Δ D = 137.0 kJ mol –1 , calculate the value of K P at 298.15K. Does this equilibrium constant make sense (relative to the 1000 K value) in terms of the balance of between enthalpy and entropy? c. Calculate reaction G Δ D for this reaction at 298.15 K. 2. The phase diagram of NH 3 can be characterized by the following information. The normal melting and boiling temperatures are 195.2 and 239.82 K, respectively; the triple point pressure and temperature are 6077 Pa and 195.41 K, respectively. The critical point parameters are 112.8 × 10 5 Pa and 405.5 K. Make a sketch of the P-T phase diagram (not
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Unformatted text preview: necessarily to scale) for NH 3 . It useful to think of plotting Log P (y-axis) versus T (x-axis). Indicate a point in the phase diagram for the following conditions. For each point, state which and how many phases are present. a) 195.41 K, 1050 Pa b) 195.41 K, 6077 Pa c) 237.51 K, 101325 Pa d) 420 K, 130 × 10 5 Pa e) 190 K, 6077 Pa 3. a) Use the phase rule to determine f for an aqueous solution of HCl in equilibrium with its vapor. What would appropriate independent variables be to characterize the system? b) Use the phase rule to determine f for an aqueous solution of HCl and HI in equilibrium with its vapor. What would appropriate independent variables be to characterize the system? 4. Consider aqueous H 2 SO 4 . It and the water can ionize to form H + , OH – , HSO 4 – and SO 4 2– . What is f ? What would appropriate independent variables be to characterize the system?...
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## This note was uploaded on 07/25/2008 for the course CEM 391 taught by Professor Cuckier during the Fall '08 term at Michigan State University.

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