Top-rated ScreenCasts
| Text Section | Link to original post | Rating (out of 100) | Number of votes | Copy of rated post |
|---|---|---|---|---|
| 09.05 - Fugacity and Fugacity Coefficient | Click here. | 80 | 2 |
In a contest for "the most hated word in Chemical Engineering," fugacity won by a landslide. This video (15min, uakron.edu) reviews how the term was developed and why it's not really as bad as all that. In fact, it's a nice word that sets the stage for all of phase and reaction equilibrium with a straightforward extension of the same conceptual basis to mixtures. On second thought, perhaps the power of that conceptual basis and all that it implies is what really intimidates new students. Many perspectives have been offered to help overcome the frustration that students feel toward fugacity. If you like a comic book perspective, even that is available. Comprehension Questions: 1.What is the fugacity of a vapor phase component in a mixture according to Raoult's law? |
| 13.04 - UNIQUAC | Click here. | 80 | 4 |
UNIQUAC concepts (6:44) (msu.edu) Concepts and assumptions used in developing the UNIQUAC activity coefficient method. This method introduced the use of surface area as an important quantity in calculation of activity coefficients. |
| 15.04 - VLE calculations by an equation of state | Click here. | 80 | 1 |
PRMix.xlsx - Tutorial on use for bubble pressure (msu.edu) (10:06) An overview of the organization of PRMix.xlsx, and a tutorial on the strategy to solve bubble pressure problems. Example 15.6 is worked in the screencast. After watching this screencast, you should be able to also solve dew or flash problems if you think about the strategy used to solve the problem. You may also be interested in a similar presentation from U.Colorado (learncheme, 6min). |
| 08.02 - The Internal Energy Departure Function | Click here. | 80 | 4 |
The Internal Energy Departure Function (11min, uakron.edu) Deriving departure functions for a variety of equations of state is simplified by transforming to dimensionless units and using density instead of volume. This also leads to an extra simplification for the internal energy departure function. Comprehension Questions: 1. What is the value of T(∂P/∂T)V - P for an ideal gas? |
| 10.10 - Mixture Properties for Ideal Solutions | Click here. | 80 | 1 |
10.9 - 10.12 Mixture Properties Overview (6:53) (msu.edu) This section of the text is thick with lots of equations. It may help to filter out the most important equations and results so that you have the perspective of the overall objectives of this section. There are a lot of equations in this section to show that the component fugacity in an ideal solution is simply the mole fraction multiplied by the pure component fugacity. In a liquid mixture, this is approximated as the mole fraction times the vapor pressure! This screencast goes on to preview the most important results of the next section to help you see the overall story. |
| 01.2 Molecular Nature of Temperature, Pressure, and Energy | Click here. | 76.75 | 80 |
Molecular Nature of Energy and Temperature (msu.edu) (3:34) Comprehension Questions: 1. A 1m3 vessel contains 0.5m3 of saturated liquid in equilibrium with 0.5 m3 of saturated vapor. Which molecules are moving slower? (a) the vapor (b) the liquid (c) they are all the same. 2. A glass of ice water is sitting in your freezer, set to 0C and fully equilibrated. Which molecules are moving slower? (a) the gas (b) the liquid (c) the solid (d) they are all the same. 3. You walk into the kitchen in the morning to get some breakfast. The ceiling fan is on. You forgot your slippers. Which one is "hotter?" (a) the floor (b) the ceiling (c) the granite counter top (d) the air in the room (e) they are all the same. |
| 12.01 - The van der Waals Perspective for Mixtures | Click here. | 76.6667 | 6 |
Mixing Rules (7:23) (msu.edu) How should energy depend on composition? Should it be linear or non-linear? What does the van der Waals approach tell us about composition dependence? This screencasts shows that the mixing rule for 'a' in a random mixture should be quadratic. A linear mixing rule is usually used for the van der Waals size parameter. |
| 12.03 - Scatchard-Hildebrand Theory | Click here. | 74.5455 | 11 |
Scatchard-Hildebrand Theory (6:53) (msu.edu) Have you ever heard 'Like dissolves like'? Here we see that numerically. The Scatchard-Hildebrand model builds on the van Laar equation by using pure component information. Scatchard and Hildebrand replaced the energy departure with the experimental energy of vaporization. Because this is related to the 'a' parameter in the van Laar theory, they developed a parameter called the 'solubility parameter', but based it on the energy of vaporization. Interestingly, the model reduces to the one parameter Margules equation when the molar volumes are the same. Comprehension Questions: 1. Based on the Scatchard-Hildebrand model, arrange the following mixtures from most compatible to least compatible. (a) Pentane+hexane, (b) decane+decalin, (c) 1-hexene+dodecanol, (d) pyridine+methanol, _____ ______ ______ ______ |
| 08.01 - The Departure Function Pathway | Click here. | 73.3333 | 6 |
Departure Function Overview (11:22) (msu.edu) |
| 13.05 - UNIFAC | Click here. | 73.3333 | 6 |
UNIFAC concepts (8:17) (msu.edu) UNIFAC is an extension of the UNIQUAC method where the residual contribution is predicted based on group contributions using energy parameters regressed from a large data set of mixtures. This screecast introduces the concepts used in model development. You may want to review group contribution methods before watching this presentation. Comprehension Questions: 1. What is the difference between the upper case Θ of UNIFAC and the lower cast θ of UNIQUAC? 2. Suppose you had a mixture that was exactly the same proportions as the lower right "bubble" in slide 2. Compute ΘOH for that mixture. 3. Compare your value computed in 2 to the value given by unifac.xls. |