# Top-rated ScreenCasts

Text Section | Link to original post | Rating (out of 100) | Number of votes | Copy of rated post |
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08.07 - Implementation of Departure Functions | Click here. | 100 | 1 |
Helmholtz Departure - PR EOS (uakron.edu, 11min) This lesson focuses first and foremost on deriving the Helmholtz departure function. It illustrates the application of integral tables from Apx. B and the importance of applying the limits of integration. It is the essential starting point for deriving properties involving entropy (S,A,G) of the PREOS, and it is a convenient starting point for deriving energetic properties (U,H). |

17.07 - Temperature Dependence of Ka | Click here. | 100 | 2 |
You can customize Kcalc.xlsx (uakron.edu, 17min) to facilitate whatever calculations you may need to perform. This presentation shows how to implement VLOOKUP to automatically load the relevant Hf, Gf, and Cp values. It also shows how to automatically use the Cp/R value when a,b,c,d values for Cp are not available. Finally, it shows how a fairly general table of inlet flows, temperatures, and pressures can be used to set up the equilibrium conversion calculation. The initial set up is demonstrated for the dimethyl ether process, then revised to initiate solution of Example 17.9 for ammonia synthesis. Comprehension Questions: 1. The video shows how the shortcut Van't Hof equation can be written as lnKa=A+B/T. What are the values of A and B for the dimethyl ether process when a reference temperature of 633K is used? |

09.04 - Changes in Gibbs Energy with Pressure | Click here. | 100 | 1 |
Gibbs Energy - Nuts to Soup. (learncheme.com, 8min) It is straightforward to start from the definition of Gibbs Energy and derive all the changes in Gibbs energy. These can be graphed for H2O to see how familiar quantities from the steam tables relate to changes in this unfamiliar property. |

07.11 - The molecular basis of equations of state: analytical theories | Click here. | 100 | 1 |
Nature of Molecular Energy - Example Calculation(8min, uakron.edu) Given an estimate for the radial distribution function (RDF) integrate to obtain an estimate of the internal energy. The result provides an alternative to the attractive term of the vdW EOS. |

07.11 - The molecular basis of equations of state: analytical theories | Click here. | 100 | 1 |
Nature of Molecular Parking Lots - RDFs(20min, uakron.edu) Molecules occupy space and they move around until they find their equilibrium pressure at a given density and temperature. Cars in a parking lot behave in a similar fashion except the parking lot is in 2D vs. 3D. Despite this exception, we can understand a lot about molecular distributions by thinking about how repulsive and attractive forces affect car parking. For example, one important consideration is that you should not expect to see two cars parked in the same space at the same time! That's entirely analogous for molecular parking. Simple ideas like this lead to an intuitive understanding of the number of molecules distributed at each distance around a central molecule. From there, it is straightforward to multiply the energy at a given distance (ie. u(r) ) by the number of molecules at that distance (aka. g(r) ), and integrate to obtain the total energy. A similar integral over intermolecular forces leads to the pressure. And, voila! we have a new conceptual route to developing engineering equations of state. |

09.05 - Fugacity and Fugacity Coefficient | Click here. | 100 | 1 |
In a contest for "the most hated word in Chemical Engineering," Comprehension Questions: 1.What is the fugacity of a vapor phase component in a mixture according to Raoult's law? |

17.05 - Effect of Pressure, Inerts, Feed Ratios | Click here. | 100 | 1 |
How to push, pull, persuade a reaction (3:32) (msu.edu) Pressure can be used to influence conversion for reactions where gas phase species are present. Feed ratios, inerts, or simultaneous reactions can also be used. Comprehension Questions: 1. The principle by which a change in temperature, pressure, or concentration leads to a counteracting change in equilibrium is known as:_____. |

17.06 Determining the Spontaneity of Reactions | Click here. | 100 | 1 |
Which way will a reaction go? (3:40) (msu.edu) When both reactants and products are present in a reactng mixture, the direction the reaction will proceed is not necessarily indicated by the sign of ΔG Comprehension Questions: (Hint: review Example 17.1 before answering.) 1. CO and H2 are fed in a |

13.04 - UNIQUAC | Click here. | 100 | 2 |
Volumes and Areas from Group Contributions (3:04) Group contributions are used widely in property prediction. The volumes and surface areas have been determined by x-ray data and high-temperature collision data. The UNIQUAC and UNIFAC activity coefficient methods use these quantities to calculation volume fractions and surface area fractions. The assignment of functional groups for a molecule must be done carefully to assure agreement with the groups used by the model developers. Comprehension Questions: 1. Estimate R and Q for 1,4 dihydroxy benzene. 2. Estimate R and Q for n-propyl alcohol and compare them to the values for IPA. 3. Estimate R and Q for methyl-npropyl ketone. |

03.3 - Introduction to Mixture Properties | Click here. | 100 | 1 |
Props.xlsx has a lot of data, but usually we are only interested in a few components at a time. Adding a few lines at the top and applying the VLookup function makes it easy to tabulate the properties you need. (8min, uakron.edu) Comprehension questions 1. Download the latest version of Props.xlsx from sourceforge. Add lines to support 8 components of interest and cells to compute Psat given T as input and Tsat given P as input by appropriately arranging Eqn. 2.47. Add a column for computing Hvap at Tsat for each component by Eqn. 2.45. 2. Insert a sheet(tab) called Hrxn in Props.xlsx. Types the names for components in the reaction CO+0.5O2=CO2. Use VLookup to tabulate the Hf values for each component. To the left of the name column, insert cells to represent the stoichiometric coefficients. Then calculate the heat of reaction by using the sumproduct() function applied to the stoichiometric coefficients and Hf values. Check your result with a hand calculation. 3. Download the latest versions of PREOS.xls and Props.xlsx from sourceforge. Update the Props tab appropriately. Then implement the VLookup function on the ThermoProps tab of PREOS so all you need to do is type the name of the compound of interest in order to update the ThermoProps sheet to all properties of interest. We discuss how to use PREOS.xls to solve problems in Unit II. |