A. Discussion Problems
A1. Return to your successful solution of a fairly difficult problem in one of your previous technical courses (preferably chemical engineering). Look at this solution but from the point of view of the process used to solve the problem instead of the technical details. Did you follow a structured method? Most people don't at first. Did you eventually do most of the steps listed? Usually, the define, explore, plan, and do it steps are done sometime during the solution. Rearrange your solution so that these steps are in order. Did you check your solution? If not, do that now. Finally, try generalizing your solution.
A2. Without returning to the book, answer the following:
- Define a unit operation. Give a few examples.
- What is the equilibrium stage concept?
- What are the steps in the systematic problem solving approach? Explain each step in your own words.
A3. The equilibrium stage concept
- is a hypothetical construct.
- assumes that phases leaving the stage are in equilibrium.
- is useful even when phases are not in equilibrium.
- all of the above.
A4. If you have studied heat transfer, relate Eq. (1-4) to the similar basic definition of heat transfer by conduction and convection.
A5. Do you satisfy the prerequisites? If not, how can you remedy this situation?
A6. Develop a key relations chart (one page or less) for this chapter. A key relations chart is a summary of everything you need to solve problems or answer questions from the chapter. In general, it will include equations, sketches, and key words. Organize it in your own way. The purpose of developing a key relations chart is to force your brain to actively organize the material. This will greatly aid you in remembering the material.
B. Generation of Alternatives
B1. List as many products and how they are purified or separated as you can. Go to a large supermarket and look at some of the household products. How many of these could you separate? At the end of this course you will know how to purify most of the liquid products.
B2. Some separation methods are common in homes in the United States. Most of these are concerned with water treatment. List the separations that you are familiar with and briefly describe how you think they work.
B3. The body uses several membrane separation methods. List as many of these as you can and describe how you think they work.
B4. Separation operations are very common in chemistry laboratories. List the separations that you employed in various chemistry labs.
C1. Write the mass and energy balances (in general form) for the separator shown in Figure 1-1. If you have difficulty with this, review a book on mass and energy balances.
D1. One of the prerequisites for study of separations is the ability to convert from weight to mole fractions and vice versa. As a refresher in this conversion, solve the following problem: We have a flow rate of 1500 kmol/h of a feed that is 40 mol% ethanol and 60 mol% water. What is the weight fraction of ethanol, and what is the total flow rate in pounds per hour?
E. Complex Problems
There are no complex problems for this chapter.
F. Problems Using Other Resources
F1. Look through several recent issues of Chemical Engineering magazine or similar technical magazines and find an article that contains a process flow chart. Read the article and write a short (less than one page) critique. Explicitly comment on whether the flow sheet for the process fits (at least approximately) the general flow sheet shown in Figure 1-1.
F2. Arrange a tour of the unit operations laboratory in your institution to observe the different types of separation equipment. Note that although this equipment is often much larger than the separation equipment that you used in chemistry laboratory, it is much smaller than industrial-scale equipment.
G. Simulator Problems
There are no simulator problems for this chapter.
H. Computer Spreadsheet Problems
There are no computer spreadsheet problems for this chapter.