Top-rated ScreenCasts

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13.04 - UNIQUAC Click here. 73.33329999999999 3

UNIQUAC concepts (6:44) (

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.

10.03 - Binary VLE using Raoult's Law Click here. 73.33329999999999 3

Raoult's Law Calculation Procedures (11:45) (
Details on how to implement bubble, dew, and flash calculations for Raoult's Law. This screencast shows sample calculations for the bubble pressure and dew pressure of methanol+ethanol.

Comprehension Questions: Assume the ideal solution SCVP model (Eqns. 2.47 and 10.8).

1. Estimate the bubble pressure (bars) of 30% acetone + 70% benzene at 333K.
2. Estimate the dew temperature (K) of 30% acetone + 70% benzene at 1 bar.
3. Estimate the fraction vapor and phase compositions ethylamine+ethanol at 298K, 400mmHg and a feed of 60%amine.

07.05 Cubic Equations of State Click here. 73.33329999999999 3

Virial and Cubic EOS (11:18) (
Discusses the strategy of the virial EOS and the cubic EOS and the strategy used to solve as a cubic in Z. Gives formulas for calculating the a and b parameters of both the vdW and Peng-Robinson EOS's, as well as the virial EOS. You might want to watch the video on "Visualizing the vdW EOS" if you want to understand where the equations for a and b come from or how to make quantitative plots of isotherms.

Comprehension Questions:

1. To what region of pressure is the virial EOS limited at a given temperature? Why?
2. Is the Pitzer EOS limited to the same conditions as the virial EOS?
3. Is the virial EOS a 2-parameter or 3-parameter EOS?
4. Is the Peng-Robinson (PR) EOS a 2-parameter or 3-parameter EOS?
5. What is the primary shortcoming of the vdW EOS, as described on slide 4 of this presentation?
6. Is the PR EOS limited to the same conditions as the virial EOS? Explain.
7. How does the "fugacity" help you to identify the stable root of a cubic EOS?
8. When there are 3 real roots to a cubic EOS, what do we do with the center root? Why?

08.02 - The Internal Energy Departure Function Click here. 73.33329999999999 3

The Internal Energy Departure Function (11min, 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?
2. What is the value of (∂U/∂V)T for an ideal gas and how can you explain this result at the molecular scale?
3. The Redlich-Kwong (RK) EOS is: P=RT/(V-b) -a/(V2RT1.5). Use Eqn. 8.13 to solve for (U-Uig)/RT of the RK EOS.
4. The RK EOS can be written as: Z = 1/(1-) - /(RT1.5). Use Eqn. 8.14 to solve for (U-Uig)/RT of the RK EOS.

13.05 - UNIFAC Click here. 73.33329999999999 3

UNIFAC concepts (8:17) (

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.

04.02 The Microscopic View of Entropy Click here. 72 5

Principles of Probability III, Distributions, Normalizing, Distribution Functions, Moments, Variance. This screencast extends beyond material covered in the textbook, but may be helpful if you study statistical mechanics in another course. (, 15min) (Flash)

13.01 - Local Composition Theory Click here. 71.11109999999999 9

Local Composition Concepts (6:51) (

The local composition models of chapter 13 share common features covered in this screencasts. An understanding of these principles will make all the algebra in the models less daunting.

Comprehension Questions:

1. In the picture of molecules given in the presentation on slide 2, what is the numerical value of the local composition x11?
2. In the same picture, what is overall composition x1?
3. What value of Ω21 can you infer from 1 and 2 above and the equations on slide 3?

12.01 - The van der Waals Perspective for Mixtures Click here. 70 4

Mixing Rules (7:23) (

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.

11.13 - Osmotic Pressure Click here. 70 2

MW of protein by osmotic pressure - (8:23) (

An application of osmotic pressure measurement to determine MW of a protein.

12.03 - Scatchard-Hildebrand Theory Click here. 68.5714 7

Scatchard-Hildebrand Theory (6:53) (

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,
Most compatible                                                                     Least compatible

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