# Top-rated ScreenCasts

Text Section | Link to original post | Rating (out of 100) | Number of votes | Copy of rated post |
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13.02 - Wilson's Equation | Click here. | 66.6667 | 6 |
Wilson's model concepts (2:44) (msu.edu) The background on the assumptions and development of Wilson's activity coefficient model. Comprehension Questions: 1. What value is assumed by Wilson's model for the coordination number ( |

11.02 - Calculations with Activity Coefficients | Click here. | 65 | 4 |
This example shows how to incorporate activity calculations into Excel for solutions that follow the Margules 1-parameter (M1) model.(9min, uakron.edu) You should be able to adapt this procedure along with the procedure for the multicomponent ideal solutions to create a multicomponent M1 model. If you are having trouble, the video for the multicomponent SSCED model illustrates a very similar procedure. You can check your answers by putting in the same component twice. For example, instead of an equimolar binary mixture, input a quaternary mixture with 0.25 moles of methanol, 0.25 methanol (ie. type it as if it was another component), 0.25 of benzene and 0.25 of benzene. If you don't get the same results as for the binary equimolar system, check your calculations.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: Assume the SCVP model (Eq. 2.47). |

06.2 Derivative Relations | Click here. | 65 | 4 |
Exact Differentials and Partial Derivatives (LearnChemE.com, 5min) This math review puts into context the discussion of exact differentials in Section 6.2 of the textbook using an example related to the volume of a cylinder. Comprehension Questions: 1. Given that dU = TdS - PdV, what derivative relation comes from setting ∂ 2. Given that dA = -SdT - PdV, what derivative relation comes from setting ∂ 3. Given that dG = -SdT + VdP, what derivative relation comes from setting ∂ |

04.02 The Microscopic View of Entropy | Click here. | 65 | 4 |
Principles of Probability I, General Concepts, Correlated and Conditional Events. (msu.edu, 17min) (Flash) |

04.02 The Microscopic View of Entropy | Click here. | 65 | 4 |
Principles of Probability II, Counting Events, Permutations and Combinations. This part discusses the binomial and multinomial coefficients for putting particles in boxes. The binomial and multinomial coefficient are used in section 4.2 to quantify configurational entropy. (msu.edu, 16min) (Flash) You might like to check out the sample calculations below before attempting the comprehension questions. |

03.6 - Energy Balance for Reacting Systems | Click here. | 60 | 1 |
Heat Removal from a Chemical Reactor (uakron, 8min) determines heat removal so that a chemical reactor is isothermal following the pathway of Figure 3.5b using the pathway of Figure 2.6c if a heat of vaporization is involved. The reaction is: N2 + 3H2 = 2NH3 at 350C and 1 bar. The pathway to go from products to the reference condition is to correct for any liquid formation at the conditions of the product stream then cool/heat the products to 25C (the reference temperature), then "unreact" them back to their elements of formation. Summing up the enthalpy changes over these steps gives the overall enthalpy of the reactor outlet stream. The same procedure applied to the reactor inlet gives the overall enthalpy of reactor inlet stream. Then the heat duty of the reactor is simply the difference between the two stream enthalpies. Comprehension Questions: |

07.08 Matching The Critical Point | Click here. | 60 | 2 | |

01.5 Real Fluids and Tabulated Properties | Click here. | 60 | 2 |
Steam Tables (LearnChemE.com) (5:59) calculate enthalpy of steam by interpolation |

11.12 - Lewis-Randall Rule and Henry's Law | Click here. | 60 | 11 |
Introduction to Henry's Law (10:16) (msu.edu) Fugacities are calculated relative to standard state values, and the relations developed earlier in the chapter use a pure fluid standard state. What if the pure fluid does not exist as a liquid when pure? One choice is to use Henry's law. |

11.13 - Osmotic Pressure | Click here. | 60 | 8 |
Osmotic Pressure (7:23) (Learncheme.com) A derivation of the relation for osmotic pressure, and an explanation of why the pressures are different on each side of the semi-permeable membrane. |

Visualizing the vdW EOS (uakron.edu, 16min) Building on solving for density, describes plotting dimensionless isotherms of the vdW EOS for methane at 5 temperatures, two subcritical, two supercritical, and one at the critical condition. From these isotherms in dimensionless form, it is possible to identify the critical point as the location of the inflection point where the temperature first exits the 3-root region. This method can be adapted to any equation of state, whether it is cubic or not. The illustration was adapted from a

sample test problem. This screencast also addresses the meaning of the region where the pressure goes negative, with a (possibly disturbing) story about a blood-sucking octopus.Comprehension Questions:

1. What are the dimensions of the quantity (

bP/RT)?2. Starting with the expression for

Z(ρ,T), rewrite the vdW EOS to solve for the quantity (bP/RT) in terms of (bρ) and (a/bRT).3. Consider the following EOS:

Z= 1 + 2bρ/(1-2bρ) - (a/bRT) /(1-bρ)^{2}. Estimate the value ofbP_{c}/(RT_{c}) for this EOS.4. Consider the following EOS:

Z= 1 + 2bρ/(1-2bρ) - (a/bRT) /(1-bρ)^{2}. Estimate the value of (a/bRT) for this EOS._{c}5. Compute the values of

a(J-cm^{3}/mol^{2}) andb(cm^{3}/mol) for methane according to this new EOS.