In the Classroom
Introducing Third-Year Chemistry Students to the Planning and Design of an Experimental Program Jeffrey G. Dunn, David N. Phillips, and Wilhelm van Bronswijk School of Applied Chemistry, Curtin University of Technology, P.O. Box U1987, Perth, Western Australia, Australia, 6001 The inorganic chemistry staff at Curtin University of Technology have planned units in the applied chemistry degree course that systematically help students develop a range of skills and techniques that will assist them in experimental program design and planning, an ability they will need to use frequently when they gain employment or proceed into higher degree programs. In the first semester of the second year of the course they follow set class exercises in an analytical chemistry unit to further their analytical skills (1). In the second semester of the second year we introduce them to so-called “mini-projects”, where they work in groups of three over a period of some six weeks to gain their first insight to solving a chemistry-based problem. In the second semester of the third and final year of the course, they individually undertake a major chemistry project, which occupies approximately one and a half days a week. This paper describes a section of the first-semester third-year inorganic chemistry unit where 12 hours of practical laboratory time have been sacrificed in favor of giving students an experience in planning and designing an experimental program. It is a pencil-and-paper activity involving the design and planning of an experimental program that may lead to the solution of the problem. These skills are a prerequisite to any experimental activity. We provide the students with a list of problems similar to those that a new graduate could encounter on commencing employment in the chemical industry. They are real problems, which the inorganic chemistry staff of the school have been previously asked to solve for local industry, examples of which are shown in Table 1. Zoller (2) and Ashmore et al. (3) have also suggested that students be given the opportunity to experience reasoning and understanding, solving by search and selection of appropriate information, and evaluation by selecting and evaluating the best solution. Woods (4) has proposed a fivestep approach to analyzing problems: define the problem, think about it, plan, do it, and evaluate. He considered analysis, synthesis, decision making, and generalization as the four major skills that are constantly used in such a strategy. Student Program A staff member acts as the “client”, and the students are the “consultant”. The aim is that by a series of inter-
Table 1. Typical Problem Solving Topicsa Title
Problem
Performance of concrete roof tiles in coastal regions
Concrete roof tile manufacturers claim that their tiles are more suited for use in coastal regions than ceramic tiles. How would you demonstrate this?
Sulfide materials used as analytical A sample of CuS is used in a standards laboratory as a standard material. However, the determined Cu values decrease quite markedly between one year and the next. Why does this happen and how can it be avoided? Building contractor sued for not meeting building specifications
A building contractor is being sued because it is claimed that he used a mixture of blast furnace slag and cement instead of a pure cement in his concrete mixture. Could you devise a suitable method for distinguishing between cement with and without blast furnace slag?
Moisture expansion of clay bricks
A brick manufacturer is producing fired clay bricks of excessively high moisture expansion. How would you measure and remedy this excessive expansion?
a
Outlines of other topics may be obtained from any of the authors.
views between client and consultant, the students can refine a vague problem statement into a quantitative statement and from this develop a proposal to investigate the problem in order to confirm the cause. This proposal is submitted to the client for assessment. The suggested interview program given to the students is shown in Table 2, and students are expected to arrange one meeting with the supervisor in each week. Before the first meeting, the students must have read books, encyclopedias, and general articles to gain an overview of the problem. Reference 4 is provided to give an insight to successful problem analysis. The plaster-popping problem is given to students to illustrate the approach to such design and planning.
Step 1. Define the Problem Clearly The initial statement “there is something wrong with this plaster” is not a problem, it is a statement of fact. It is of little value to the problem solver, because it gives no in-
Table 2. The Client/Consultant Program
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Week 1
Week 2
Students ask questions to identify the problem to which the client provides the answers and any necessary guidance. The results of this first meeting should be that the problem is redefined in more precise terms
Students need to have listed the variables, or properties, which may give rise to the problem. Each of these variables, including their possible relative importance, are discussed with the client in detail.
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Week 3 Students present an outline of their design and plan, including details of the type of experimentation that would be used to gather the required data, and discuss their appropriateness with the client.
In the Classroom dication of how to proceed with an investigational approach. By a series of questions, however, it may be possible to convert this ill-defined statement into a problem definition. Q. How do you know there is something wrong with the plaster? A. Small pits appear after fresh plaster has been on the wall for 3-6 months. Q. How long has this been going on?
Step 3. Read Consult general texts on the topic to get an understanding of what is important in the area. For example, read texts such as Kirk–Othmer (5) and texts and articles on plaster production and plaster setting. Obviously, pay special attention to any mention of problems encountered, which might suggest further possible solutions to the problem or even bear directly on it.
A. About 9 months. Q. Have you changed anything in your production run in the last 9 months.
Step 4. List All Possible Hypotheses The student should by now be in a position to define many of the possible causes of the problem, which should be listed in order of likelihood.
A. Yes—lime is added to the plaster in about 5% quantities. This limestone used to be obtained from land quarries, but about 9 months ago the company changed to dredged shell deposits from the sea.
Step 5. Experimental Design Design laboratory-scale experiments to test each of the above hypotheses, or a series of experiments, which may be necessary to solve the problem.
The problem may now be refined to: “A possible investigation into the effects of sea limestone on the behavior of set plaster”. This, of course, may not be the only cause of the problem, and further questioning might elicit further variables. As more is learned about the system, the problem statement might be further refined.
Step 2. Define as Many of the System Variables as Possible It is assumed that the problem has been correctly identified in step 1. If all possible causes of the observed effect are to be considered, then all system variables need to be listed. In this example, that would include the composition of materials used, environmental factors, and plant conditions— that is, composition (major and minor components) of gypsum, the important plant variables used in the production of lime and plaster, and the composition of the final product. Have any recent changes occurred in any of these parameters? If so, what are they and why? Table 3. Assessment Criteria Area
Mark
Problem definition expressed in precise and quantitative terms
10
Consultation with supervisor: well-prepared, shrewd questioning at each stage
15
List of parameters, variables, causes, including hypothesis statements
20
Outline of experimental program, including measurements to be made, techniques, equipment required, reasons for choice, presentation of results
30
Report presentation: well organized, attractive, free of errors
10
Evidence of use of literature, list of references in correct format
Total
15
100
Step 6. Results and Interpretation of Results Postulate the type of results that could be expected, suggest what inferences may be drawn from them, and methods of presenting result. Assessment The students are required to submit a final report of about 6–8 pages. This is expected to be a quality word-processed report using Microsoft Word, with data presented using Microsoft Excel. The assessment is based on the criteria and mark allocation shown in Table 3. Conclusions Because the design and planning of an experimental program is often an important aspect of the job description of recent-graduate employees in the chemical industry, time should be devoted to this activity in an undergraduate course. Our students enjoy this activity, and it is highly commended by the School of Applied Chemistry’s Advisory Board, which primarily comprises industrial chemists. Literature Cited 1. Dunn, J. G.; Mullings, L. R.; Phillips, D. N. J. Chem. Educ. 1995, 72, 220–221. 2. Zoller, U. J. Chem. Educ. 1987, 64, 510–512. 3. Ashmore, A. D.; Frazer, M. J.; Casey, R. J. J. Chem. Educ. 1979, 56, 377–379. 4. Woods, D. R. ChemTech 1983, 13, 459–462. 5. Kirk-Othmer Encyclopedia of Chemical Technology, 2nd. ed.; Standen, A., Ed.; Wiley Interscience: New York, 1963– 1972.
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