HW5-2011 - We let the pressure drop to 101.3 kpa by briey...

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ECH 152A, Fall 2011, Roland Faller Homework 5, October 24, 2011 Due: October 31, Beginning of Lecture 1. (8 points) An ideal gas is initially at 600 K and 1 Mpa. It undergoes a reversible process in four steps. We first reduce pressure isothermally to 300 kpa to arrive at state 2. We then reduce pressure isochorically to 200 kpa to arrive at state 3. Then we reduce volume at constant pressure to state 4. Finally we return adiabatically to the initial state 1. (a) Sketch the complete cycle in a PV diagram. (b) Determine p and T at states 2 - 4 (c) Calculate Q, W, Δ U, Δ H for every step. 2. (5 points) Calculate the heat capacity of a gas from the following information: We start with an equilibrium in a closed container at 25 C and 121.3 kPa.
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Unformatted text preview: We let the pressure drop to 101.3 kpa by briey opening the container. After resealing we heat back to 25 C and arrive at 104 kpa. Determine c P assuming an ideal gas and reversible and adiabatic exchanges where appropriate. 3. (7 points) Methyl chloride at 373 K (100 C) has the following virial coecients B =-242 . 5cm 3 / mol , C = 25 . 2 10 3 cm 6 mol-2 Calculate the work of an isothermal reversible compression of 1 mol from 100 kpa to 5 Mpa. (a) Use the virial equation in volume Z = 1 + B V + C V 2 (b) Use the pressure variant of the virial equation Z = 1 + B p + c p 2 B = B RT , C = C-B 2 ( RT ) 2 (c) Why are the results slightly dierent?...
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