|Text Section||Link to original post||Rating (out of 100)||Number of votes||Copy of rated post|
|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.
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?
|05.4 - Refrigeration||Click here.||100||2||
Refrigeration Cycle Introduction (LearnChemE.com, 3min) explains each step in an ordinary vapor compression (OVC) refrigeration cycle and the energy balance for the step. You might also enjoy the more classical introduction (USAF, 11min) representing your tax dollars at work. The musical introduction is quite impressive and several common misconceptions are addressed near the end of the video.
|07.06 Solving The Cubic EOS for Z||Click here.||100||1||
6. Solving for density (uakron.edu, 9min) An alternative to solving directly for Z is to solve for density then compute Z=P/(ρRT). This requires iterative solution and it is not very expedient for repetitive calculations, but it requires no rearrangement of the EOS and it is easy to visualize. This sample calculation is illustrated here for the vdW EOS, solving for the density of propane as: (a) liquid 25C,11bars (b) liquid 62C,35bars (c) vapor at 80C and 30bars.
1. Solve for the liquid density (mol/cm3) of n-pentane at 62C and 2.5 bars using the vdW EOS.
|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 ΔGo or Ka. Rather, it is determined by ΔG. This screencasts provides guidance for understanding this concept.
Comprehension Questions: (Hint: review Example 17.1 before answering.)
1. CO and H2 are fed in a 2:1 ratio to a reactor at 500K and 20 bars with a catalyst that favors only CH3OH as its product. When the conversion of H2 is 32%, will the reaction go forwards towards product or back to reactants?
|08.02 - The Internal Energy Departure Function||Click here.||100||1||
Departure Function Derivation Principles (8:03) (msu.edu)
|11.02 - Calculations with Activity Coefficients||Click here.||96||5||
Dew Temperature (7:57) (msu.edu)
The culmination of the activity coefficient method is application of the fitted activity coefficients to extrapolate from limited experiments in a Stage III calculation. The recommended order of study is 1) Bubble Pressure; 2) Bubble Temperature; 3) Dew Pressure; 4) Dew Temperature. Note that an entire Txy diagram can be generated with bubble temperature calculations; no dew calculations are required. However, many applications require dew calculations, so they cannot be avoided. The dew calculations are more complicated than bubble calculations, because the liquid activity coefficients are not known until the unknown liquid mole fractions are found. This screencast describes the procedure and how to implement the method in Matlab or Excel.
|10.01 - Introduction to Phase Diagrams||Click here.||96||5||
Introduction to Phase Behavior (9:37) (msu.edu)
1. Referring to the Txy diagram on slide 3, estimate T, nature (ie. L,V, V+L, L+L), composition(s), and amount of the phase(s) for points: a, b. d, g.
|07.09 -The Molecular Basis of Equations of State: Concepts and Notation||Click here.||93.3333||3||
Nature of Molecular Interactions - Macro To Nano(8min). (uakron.edu) Instead of matching the critical point, we can use experimental data for density vs. temperature from NIST as a means of characterizing the attractive energy and repulsive volume. A plot of compressibility factor vs. reciprocal temperature exhibits fairly linear behavior in the liquid region. Matching the slope and intercept of this line characterizes two parameters. This characterization may be even more useful than using the critical point if you are more interested in liquid densities than the critical point. In a similar manner, you could derive an EOS based on square-well (SW) simulations and use the SW EOS to match the NIST data(11min), as shown in this sample calculation of the ε and σ values for the SW potential. In this lesson, we learn how to characterize the forces between individual atoms, which may seem quite unreal or impractical when you first encounter it. On the other hand, "nanotechnology" is a scientific discipline that explores how the manipulation of nanostructure is now quite real with very significant practical implications. "The world's smallest movie" shows dancing molecules, (IBM, 2min) demonstrating the reality of molecular manipulation, and the accompanying text explains some of the practical implications. Along similar lines, researchers at LLNL and CalTech have developed 3D printers that can display "voxels" (the 3D analog of pixels) of ~1nm3. That's around 10-100 atoms per voxel. Since 2013-14, chemical/materials engineers have been building nanostructures (TEDX, 13min) in the same way that civil engineers build infrastructure.
|14.10 Solid-liquid Equilibria||Click here.||93.3333||3||
SLE using Excel with the M1 model (7min, uakron.edu)
Similar to LLE in Excel, the iteration feature can be used to quickly solve for SLE at multiple temperatures.
|07.06 Solving The Cubic EOS for Z||Click here.||93.3333||3||
1. Peng-Robinson PVT Properties - Excel (3:30) (msu.edu)
Introduction to PVT calculations using the Peng-Robinson workbook Preos.xlsx. Includes hints on changing the fluid and determining stable roots.
1. At 180K, what value of pressure gives you the minimum value for Z of methane? Hint: don't call solver.
2. At 30 bar, what value of pressure gives Z=0.95 for methane?
3. Compute the molar volume(s) (cm3/mol) for argon at 100K for each of the following?