RESEARCH ARTICLE

 

An approach to dealing with the difficulties undergraduate chemistry students experience with stoichiometry

 

 

Fiona Marais; Sandra Combrinck

Department of Chemistry, Tshwane University of Technology, Private Bag X680, Pretoria 0001, Republic of South Africa

 

 

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ABSTRACT

Chemistry for first year students has been identified by Tshwane University of Technology as one of the subjects with a low pass rate. It is apparent that students often memorize formulae and definitions, without understanding the underlying concepts required to work with abstract units of measure. We have found that the majority of students at this university are unable to balance reaction equations satisfactorily. They are also unable to predict the reaction yield, or identify limiting reagents. It is imperative that these and other related problems are overcome before any meaningful change to the high failure rate at first year level will be realized. All conventional forms of lecture presentation failed to make any significant impact on the success rate. Structured worksheets were developed and used, together with tactile models, to address the problems and the initial findings showed a marked improvement. It was discovered that the students' problems originated from their inability to understand the meaning of subscripts and coefficients in chemical equations. The worksheets and the impact they have made on the students' understanding of stoichiometry are shared in this paper.

Key words: Stoichiometry, limiting reagent, worksheets, tactile models

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Full text available only in PDF format.

 

Acknowledgements

The authors express their thanks and gratitude to the staff of TUT who assisted with the worksheet intervention, Dr Rosalind Gummow (James Cook University, Townsville, Australia) who validated the PWST test, Dr Thapelo Mamiala (University of Stellenbosch) and Dr Marietjie Potgieter (University of Pretoria) for validating the worksheet intervention according to compliance with the programme content, and Dr Marietjie Potgieter for a critical review of this article.

 

References

1 L. Bell, J. Educ. Admin., 1999, 37, 1-19.         [ Links ]

2 S. Howie, Mathematics and Science Performance in Grade 8 in South Africa 1998/1999, Human Sciences Research Council, Pretoria, South Africa, 2001.         [ Links ]

3 A. Burnstein, Math, science teaching needs a shake up, Pretoria News, 9 October 2007, p 7.         [ Links ]

4 L. Rakgokong Pythagoras, 1994, 35, 14-19.         [ Links ]

5 D. R. Mulford and W.R. Robinson, J. Chem. Educ, 2002, 79, 739-744.         [ Links ]

6 A. Lourens and I.P.J. Smit, S. Afr. J. Higher Educ., 2003, 17, 169-170.         [ Links ]

7 G.M. Bodner, J. Chem. Educ., 1991, 68, 385-388.         [ Links ]

8 M.E. Beeth, J. Sci. Teach. Educ., 1998, 9, 49-61.         [ Links ]

9 H.L. Botha and C.D. Celliers, S. Afr. J. Higher Educ., 1999, 13, 144-152.         [ Links ]

10 W.R. Kilfoil, S. Afr. J. Higher Educ., 1999, 13, 46-58.         [ Links ]

11 F. Marais and I. Louw, The influence of prior learning as a barrier to learning for students studying chemistry, Proc. Conf. International Technology Education and Development (INTED) (L.G. Chova, I. Belenguer and C. Torres, eds.), Valencia, Spain, 3-5 March, 2008.         [ Links ]

12 J.T.R. Cassels and A. H. Johnstone, Educ. Chem., 1983, 20, 10-11.         [ Links ]

13 D.L. Gabel and R.D. Sherwood, J. Res. Sci. Teach., 1984, 21, 843-851.         [ Links ]

14 D.L. Gabel and K.V Samuel, J. Res. Sci. Teach., 1986, 23, 165-176.         [ Links ]

15 D.L. Gabel and D.M. Bunce, Research on problem solving: chemistry, in Handbook of Research on Science Teaching and Learning. A Project of the National Science Teachers' Association (D.L. Gabel, ed.), Macmillan, New York, NY, USA, 1994, pp. 301-325.         [ Links ]

16 D.L. Gabel, K.V. Samuel and D. Hunn, J. Chem. Educ., 1987, 64, 695-697.         [ Links ]

17 M. Potgieter, B. Davidowitz and S. Mathabatha, Do they know that they don't know? The relationship between confidence and performance of first year chemistry students at three tertiary institutions in South Africa. Proc. Conf. Australasian Science Education Research Association, Freemantle, Australia, 2007.         [ Links ]

18 A.H. Johnstone, Chem. Educ. Res. Prac., 2000, 1, 9-15.         [ Links ]

19 W. Huitt and J. Hummel, Piaget's theory of cognitive development, http://chiron.valdosta.edu/whuitt/col/cogsys/piaget (accessed 14 September 2008).         [ Links ]

20 A. Brook, M. Briggs and R. Driver, Aspects of Secondary Students' Understanding of the Particulate Nature of Matter, Centre for Studies in Science and Mathematics Education, Glasgow, UK, 1984.         [ Links ]

21 M. Potgieter,J.M. Rogan and S. Howie, Afr. J. Res. Math. Sci. Tech. Educ., 2005, 9, 121-134.         [ Links ]

22 F. Marais, The use of structured worksheets as a tool to target identified learning difficulties of first year chemistry students, Proc. Intern. Conf. Chem. Educ., Mauritius, 3-8 August 2008.         [ Links ]

23 S. Yitbarak, Questions we ask and misconceptions of chemical concepts in African context, http://www.uni_muenster.de/imperia/md/content/did (accessed 12 March 2008).         [ Links ]

24 R. Gummow, Structured Worksheet Design, Tshwane University of Technology, Pretoria, South Africa, 2007.         [ Links ]

25 R. Duit and D. F. Treagust, Int. J. Sci. Educ., 2003, 25, 671-688.         [ Links ]

26 P. Webb and D.F. Treagust, Res. Sci. Educ., 2006, 36, 381-401.         [ Links ]

 

 

Received 12 November 2008
Revised 11 February 2009
Accepted 4 March 2009

 

 

* To whom correspondence should be addressed. E-mail: maraisf@tut.ac.za