Tips for Homework set 4 The homework is designed to practice main principles that we discussed in the classroom. As in other chemical engineering classes, we discuss important theories in the class and leave the use of these theories for self-study in the homework. In this way, you can develop problem solving skills. The exams will be the same way – practicing “problem solving skills”. Some of the textbook examples in Chap 7 are so important that I include them in the homework set 4 to make sure everyone studies these problems… By following the textbook solutions, these problems can be solved easily; but that does automatically guarantee that you will be able to solve the same problems in the future. You may want to memorize the problem solving approaches…

#1.. see Example 7.4, ChE 304 Lecture Notes #2.. Bubble temperature calculation using Raoult’s law. Read Example 7.6. You need to solve the bubble temperature calculation equation (discussed in Lecture 12) in a non- algebraic way. Use the following function in Mathematica: FindRoot[ equation to be solved, {unknown variable, initial guess}] #3.. Dew temperature calculation using Raoult’s law. See Example 7.7. Use “FindRoot” function. #4.. Practicing flash calculation. We derived this in Lecture 12 class. #5.. Use the method described in Example 7.14 or in the “Lecture 13 Enthalpy Chart” PowerPoint file which is available after Oct 18 on the Angel. #6.. Can be solved using equations we studied in Lecture 12 – “partial molar properties of component i in non-ideal solutions”.

#7.. Read Examples 7.16 and 7.17 (Lecture 15) #8.. Read Examples 7.18 (Lecture 15) #9.. Read Example 7.19 (Lecture 15) #10.. (a), (b), (c)  same as #2, #3, #4. The only differences are that #2, #3, #4 are for ideal solutions, and #10 (a), (b), (c) are for non-ideal solutions. In (c), you need solve three equations simultaneously to find three variables. What are those three equations? The “FindRoot” function in Mathematica can be used to solve multiple equations – FindRoot[{equation 1, equation 2, equation 3},{{variable 1, initial guess}, {variable 2, initial guess}, {variable 3, initial guess}}] (d) You need to solve two equations simultaneous using the “FindRoot” function to get T and x 1 (or y 1 ) at the azeotropic condition. What are those equations? #11.. How to use HYSYS to construct Pxy diagram of non-ideal solution using different binary interaction coefficients obtained from (a) ideal solution model, (b) UNIFAC approximation and (c) the DECHEMA data bank. From comparison of these Pxy diagrams, you will learn the essence of these different models.