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09.06 - Fugacity Criteria for Phase Equilibria Click here. 20 1

When liquid is added to an evacuated tank of fixed volume, equilibrium is established between the vapor and liquid. (3min,learncheme.com) The fugacity criterion characterizes this equilibrium as occurring when the escaping tendency from each phase is equal.

08.07 - Implementation of Departure Functions Click here. 20 1

Internal Energy Departure - PR EOS starting from Helmholtz Departure (uakron.edu,9min) This sample derivation supplements what is in the textbook by starting from the Helmholtz departure function. It also includes a few intermediate steps to help clarify how the formal equations in the textbook were developed. Hopefully, seeing this content from slightly different perspectives will make it a little easier to comprehend. See also the derivation for (U-Uig).

Comprehension Questions: Starting from the Helmholtz Departure function and referring to the above results...

1. Derive the internal energy departure function for the "modified vdW" EOS.
2. Derive the entropy departure function for the "modified vdW" EOS. (Hint: A=U-TS)
3. Derive the internal energy departure function for the "Scott+TPT" EOS.

04.03 The Macroscopic View of Entropy Click here. 20 1

Once we establish equations relating macroscopic properties to entropy changes, it becomes straightforward to compute entropy changes for all sorts of situations. To begin, we can compute entropy changes of ideal gases (learncheme, 3 min). Entropy change calculations may also take a more subtle form in evaluating reversibility (learncheme, 3min). 

Comprehension Questions: 

1. Nitrogen at 298K and 2 bars is adiabatically compressed to 375K and 5 bars in a continuous process. (a) Compute the entropy change. (b) Is this process reversible, irreversible, or impossible?
2. Nitrogen at 350K and 2 bars is adiabatically compressed to 575K and 15 bars in a piston/cylinder. (a) Compute the entropy change. (b) Is this process reversible, irreversible, or impossible?
3. Steam at 450K and 2 bars is adiabatically compressed to 575K and 15 bars in a continuous process. (a) Compute the entropy change. (b) Is this process reversible, irreversible, or impossible?
4. Steam at 450K and 2 bars is isothermally compressed to 8 bars in a continuous process. (a) Compute the entropy change. (b) Is this process reversible, irreversible, or impossible?

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