Top-rated ScreenCasts

Text Section Link to original post Rating (out of 100) Number of votes Copy of rated post
10.01 - Introduction to Phase Diagrams Click here. 84 5

Bubble, Dew, Flash Concepts and the Lever Rule (4:01) (msu.edu)

Understanding what is present (known) and not present (unkown) for a given state of a system will help you decide which routine to use. Notation is introduced for liquids, vapor, and overall compositions. Also, the lever rule concept is used throughout the chemical engineering curriculum, but it is important to see how to use compositions for the lever rule.

Comprehension Questions:

1. Which variables are fixed and which do you need to find in each of the following:
a. Bubble temperature
b. Bubble pressure
c. Dew temperature
d. Dew pressure
e. Isothermal flash
f. Adiabatic flash

13.05 - UNIFAC Click here. 82.8571 7

Unifac.xls Calculation of Bubble Temperature. (3 min) (LearnChemE.com)
Comprehension Questions: Download Unifac.xls from the software link and use it to answer the following.
1. Estimate the activity coefficient of IPA in water at 80C and xw = 0.1.
2. Estimate the fugacity for IPA in water at 80C and xw =0.1.
3. Estimate the total pressure at 80C when xw =0.1.
4. Estimate the bubble temperature of IPA in water at 760mmHg and xw =0.1.

07.06 Solving The Cubic EOS for Z Click here. 82.8571 7

3. Using Preos.xlsx and Interpreting Output (11:38) (msu.edu)
This screencast includes discussion of what we mean by the casual terminology 'three root region' and 'one root region', and how to interpret screen output. Also, the screencast spends time dicussing selection of stable roots using fugacity.

Comprehension Questions:

1. Is it possible to have a 1-root region below the critical temperature?

2. Is it possible to have a 3-root region above the critical temperature?

3. How does fugacity help us to identify the proper root to select?

4. Would argon at 5 MPa be in the 1-root or 3-root region?

07.05 Cubic Equations of State Click here. 80 1

Intro to the vdW EOS. (LearnCheme.com, 5min) Provides a brief overview of the van der Waals (vdW) 1873 equation of state (EOS), which served as a prototype for EOS development for over 100 years. Note: the vdW EOS is just one conjecture of how equations of state for real fluids may be formulated. In reality, each fluid has its own unique EOS. The vdW model conjectures that the pressure is altered relative to the ideal gas by the presence of attractive forces and repulsive forces.

Comprehension Questions:

1. Of the two parameters a and b, which is related to attractive forces and which is related to attractive forces?
2. How are the parameters a and b typically characterized/computed? ie. To what experimental constants are they related in order to compute them?
3. Is the vdW EOS an example of a 2-parameter EOS or 3-parameter EOS?
4. When writing the term (V-b) we subtract b because the molecules occupy volume and when V=b, all the "free volume" is gone. Can you explain the term (P+a/V2) in a similar manner?
5. In the presented example of CO2 at 0.2L and 269K, how does the pressure compare when computed by the ideal gas law vs. the vdW model? (Give both values.)
6. In the presented example of CO2 at 0.0L and 269K, how does the pressure compare when computed by the ideal gas law vs. the vdW model? (Give both values.)

08.05 - Summary of Density Dependent Formulas Click here. 80 1

Enthalpy Departure Function for the vdW Fluid (5min) (LearnChemE.com) This short video shows the application of Eqn. 8.24 and the van der Waals equation of state. This is a simple equation of state and the derivation is easy, so it is a good place to start in order to understand the process.

18.09 - Sillen Diagram Solution Method Click here. 80 1

 Sillen Diagram for Electrolyte Calculations (10:14) (msu.edu)

Construction of a Sillien diagram involves several steps that are hard to follow from a textbook. This screencast goes through the steps of solving Example 18.5 from the Elliott and Lira textbook using the Sillen diagram. The problem asks for the pH of a solution that is 0.01 M NaOAc.

11.13 - Osmotic Pressure Click here. 80 3

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

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

09.05 - Fugacity and Fugacity Coefficient Click here. 80 2

What is fugacity? (10min) (learncheme.com) Defines fugacity in terms of Gibbs Energy and describes the need for defining this new property as a generalization of how pressure affects ideal gases.
Comprehension Questions
1. The phases in this video start with concentrations 0.0007kg/L and 1.0 kg/L, when not at equilibrium. What are the equilibrium concentrations?
2. Why is concentration an unreliable indicator for the direction of mass transfer?
3. Name two indicators for the direction of mass transfer that are superior to concentration.  

12.07 Multicomponent Extensions of van Der Waals' Models Click here. 80 1

M1/MAB Extension of the Multicomponent Flash Spreadsheet (19min, uakron.edu) adapted from Ideal Solutions (cf Section 10.4)

Shows how to modify the spreadsheet created for Ideal Solutions (Section 10.4) to apply modified Raoult's law for 5 components using the M1/MAB model.

Note: This is a companion file in a series. You may wish to choose your own order for viewing them. For example, you should implement the first three videos before implementing this one. Also, you might like to see how to quickly visualize the Txy analog of the Pxy phase diagram. If you see a phase diagram like the ones in section 11.8, you might want to learn about LLE phase diagrams. The links on the software tutorial present a summary of the techniques to be implemented throughout Unit3 in a quick access format that is more compact than what is presented elsewhere. Some students may find it helpful to refer to this compact list when they find themselves "not being able to find the forest because of all the trees."

Comprehension Questions:
1. Find the bubble and dew pressures of an equimolar mixture of chloroform, acetone, and ethanol at 5 bars using the MAB model. Then compute V/F x and y at the pressure that is halfway between dew and bubble. Is it what you expected?
2. Find the bubble and dew pressures of an equimolar mixture of acetone, ethanol, and methane at 5 bars using the MAB model. Then compute V/F x and y at the pressure that is halfway between dew and bubble. Is it what you expected?
3. Find the bubble and dew pressures of an equimolar mixture of chloroform, acetone, and ethanol at 5 bars using the MAB model. Then compute V/F x and y at the pressure that is halfway between dew and bubble. Is it what you expected?
4. Find the bubble and dew pressures of an equimolar mixture of acetone, ethanol, and methane at 5 bars using the MAB model. Then compute V/F x and y at the pressure that is halfway between dew and bubble. Is it what you expected?

13.03 - NTRL Click here. 80 1

NRTL concepts (2:30) (msu.edu)

The concepts on the development of the NRTL activity coefficient model.

Comprehension Questions:

1. What value does the NRTL model assume for the coordination number (z)?
2. What does the acronym "NRTL" stand for?
3. What is the relation between τ12, τ21, and A12 of the M1 model when α12=0?
4. The NRTL model has one more parameter than the Wilson model. Which parameter is it and what is its default value?

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