Teaching and Learning Forum 97 [ Contents ]

Introducing third year chemistry students to the planning and design of an experimental program

Jeffrey G. Dunn, David N. Phillips and W. van Bronswijk
School of Applied Chemistry
Curtin University of Technology


The Inorganic Chemistry staff at Curtin University of Technology have planned units in the Applied Chemistry degree course which systematically help students develop a range of skills and techniques which will assist them in experimental program design and planning, an ability that they will need to use frequently either 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 second year we introduce the students to so-called "mini-projects", where they work in small 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 pencil and paper activity which involves the design and planning of an experimental program which may lead to the solution of the problem. These skills are an essential pre-requisite to any experimental activity. The students are given a list of problems from which they make a selection that is of most interest. These problems are similar to those that a new graduate could encounter on commencing employment in chemical industry. Typical examples of these problems, which the Inorganic Chemistry staff of the School have been previously asked to solve for local industry, are shown in Table 1.

Table 1: Typical Problem Solving Topics
(outlines of other topics may be obtained by contacting any one of the authors)

TitleProblem
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?
Sulphide materials used as analytical standards.A sample of CuS is used in a 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?

Zoller (2) and Ashmore et al (3) have also suggested that students should 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 five-step approach to analyzing problems: define the problem, think about it, plan, do it, and evaluate. He considered analysis, synthesis, decision making and generalisation 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 is the "consultant". The aim is that by a series of interviews between the client and the consultant, the students can refine a vague problem statement into a quantitative statement, and then 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 programme given to the students is shown in Table 2, and students are expected to arrange one meeting with the supervisor in each week. Prior to the first meeting, the students must have read books, encyclopaedias and general articles to gain an overview of the problem. Reference (4) is provided to give an insight to successful problem analysis.

Table 2: The Client/Consultant Program.

Week 1Week 2Week 3
The students ask questions to identify the problem to which the client provides the answers and any necessary guidance. The result of this first meeting should be that the problem is redefined in more precise terms. The 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. The 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.

The plaster popping problem is given to the students to illustrate the approach to such design and planning.

Step 1. Define tthe 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 indication 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?
A.About 9 months.
Q.Have you changed anything in your production run in the last 9 months.
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.

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, plant conditions etc., i.e. composition (major and minor components) of gypsum, what are the important plant variables used in the production of lime and plaster, what is the composition of the final product. Have any changes occurred in recent times to any of these parameters? If so, what are they and why?

Step 3. Read. Consult general texts on the topic to get an understanding of what is important in the topic area, e.g. read texts such as Kirk-Othmer (5), and texts and articles on plaster production and plaster setting, and obviously pay special attention to any mention of problems encountered which might suggest further possible solutions to the problem or even bear directly on the problem.

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 likelyhood.

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.

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 consisting of about 6-8 pages. This is expected to be a quality word-processed report using Microsoft Word, with data being presented using Microsoft Excel. The assessment is based on the criteria and mark allocation shown in Table 3.

Table 3: Assessment Criteria

AreaMark
Problem definition expressed in precise and quantitative terms10
Consultation with supervisor: well prepared, shrewd questioning at each stage15
List of parameters, variables, causes including hypothesis statements20
Outline of experimental programme including measurements to be made, techniques, equipment required, reasons for choice, presentation of results30
Report presentation: well organised, attractive, free of errors10
Evidence of use of literature, list of references in correct format15
Total100

Conclusions

The design and planning of an experimental program is often an important aspect of the job description of recent graduate employees in chemical industry and time should therefore 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 is primarily comprised of industrial chemists.

References

  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, Encyclopaedia of Chemical Technology, 2nd. ed., John Wiley & Son, New York.
Please cite as: Dunn, J. G., Phillips, D. N. and van Bronswijk, W. (1997). Introducing third year chemistry students to the planning and design of an experimental program. In Pospisil, R. and Willcoxson, L. (Eds), Learning Through Teaching, p267-270. Proceedings of the 6th Annual Teaching Learning Forum, Murdoch University, February 1997. Perth: Murdoch University. http://lsn.curtin.edu.au/tlf/tlf1997/dunn2.html


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