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HW5-2009

# HW5-2009 - We let the pressure drop to 101.3lkpa by...

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ECH 152A, Fall 2009, Roland Faller Homework 5, October 23, 2009 Due: October 30, Beginning of Lecture 1. (8 points) An ideal gas is initially at 600K and 1Mpa. It undergoes a reversible process in four steps. We first reduce pressure isothermally to 300kpa to arrive at state 2. We then reduce pressure isochorically to 200kpa 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 all 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 25C and 121.3 kPa.
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Unformatted text preview: We let the pressure drop to 101.3lkpa by brieﬂy opening the container. After resealing we heat back to 25C and arrive at 104kpa. Determine c P assuming an ideal gas and reversible and adiabatic exchanges where appropriate. 3. (6 points) This problem was on midterm 2, 2008 Assume a gas can be described by the following virial equation pV NRT = 1 + Bp + Cp 2 with B =-2 . 9 × 10-9 1 mole Pa and C = 2 . 1 × 10-16 1 Pa mole 2 . (a) Calculate the work required (for one mole at 370 K) to increase the pressure from 150 to 400 kpa. (b) Calculate the volumes for the beginning and ﬁnal state of part (a). (c) Redo part (a) assuming an ideal gas....
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