This article was downloaded by: [Stanford University Libraries]On: 10 October 2012, At: 17:30Publisher: RoutledgeInforma Ltd Registered in England and Wales Registered Number: 1072954Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK

International Journal of ScienceEducationPublication details, including instructions for authors andsubscription information:http://www.tandfonline.com/loi/tsed20

The development of modulesfor the teaching of chemicalequilibriumAnil C. Banerjee a & Colin N. Power* ba Regional College of Education, Mysore, Indiab School of Education, Flinders University, Adelaide,Australia

Version of record first published: 25 Feb 2007.

To cite this article: Anil C. Banerjee & Colin N. Power* (1991): The development of modulesfor the teaching of chemical equilibrium, International Journal of Science Education, 13:3,355-362

To link to this article: http://dx.doi.org/10.1080/0950069910130312

PLEASE SCROLL DOWN FOR ARTICLE

Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions

This article may be used for research, teaching, and private study purposes.Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expresslyforbidden.

The publisher does not give any warranty express or implied or make anyrepresentation that the contents will be complete or accurate or up to date. Theaccuracy of any instructions, formulae, and drug doses should be independentlyverified with primary sources. The publisher shall not be liable for any loss,actions, claims, proceedings, demand, or costs or damages whatsoever orhowsoever caused arising directly or indirectly in connection with or arising out ofthe use of this material.

INT. j . sci. EDUC., 1991, VOL. 13, NO. 3, 355-362

The development of modules for theteaching of chemical equilibrium

Anil C. Banerjee, Regional College of Education, Mysore, India,and Colin N. Power*, School of Education, Flinders University,Adelaide, Australia

Three modules on chemical equilibrium were developed as resource materials for a content-cum-methodology course in chemistry for intending teachers and also for general chemistry courses at thesenior secondary and tertiary levels. The modules deal with the qualitative and quantitative aspects ofgaseous, ionic, solubility, acid-base and redox equilibria. The modules are based on research articles onthe teaching and learning of chemical equilibrium and general science education research on misconcep-tions, conceptual difficulties and teaching strategies. The development of competence through assignedtasks was addressed. Use of these modules with 46 students on a methodology course in chemistry showeda significant development of competence in the knowledge and understanding, processes, problem-solvingand applications domains. The modules also reduced misconceptions in some aspects of equilibrium.

Introduction

Though a large body of science education research in process skills, problem-solvingskills, teaching competence, misconceptions and conceptual difficulties is availablein the literature, the use of these research results by teachers in the classroom hasbeen a challenging problem. One of the major reasons is the lack of resourcematerials in ready-to-use forms for direct use by teachers. Therefore the develop-ment of teaching modules as resource materials for intending and practising teachersin some areas of chemistry, using available research publications in the area ofscience education, seemed to be needed. With this background, three modules on theteaching of qualitative and quantitative aspects of gaseous, ionic, solubility, acid-base and redox equilibria were developed as resource materials for a content-cum-methodology course in chemistry for intending teachers and for a general chemistrycourse at the senior secondary and tertiary levels. Chemical equilibrium was chosenas the topic since a number of review articles and research publications on variousaspects of equilibrium, particularly on misconceptions and conceptual difficulties,are available.

The major objectives of these modules are:

(a) to provide teachers with resource-support materials based on scienceeducation research into the teaching and learning of various aspects ofequilibrium;

(b) to familiarize teachers with the reported literature on conceptual difficultiesand misconceptions in these areas;

•Present address: Assistant Director General for Education, UNESCO, Paris, France.

0950-0693/91 $3-00 © 1991 Taylor & Francis Ltd.

Dow

nloa

ded

by [

Stan

ford

Uni

vers

ity L

ibra

ries

] at

17:

30 1

0 O

ctob

er 2

012

356 RESEARCH REPORTS

(c) to develop and assess teaching competence in the domains of knowledge andunderstanding (concepts domains), process skills (process domains), prob-lem solving and application in everyday life (applications domains), and alsoin the identification of misconceptions.

Each module developed has the following structure: (a) a statement of content to becovered; (b) a statement of concepts to be developed; (c) the assumed priorknowledge of students; (d) process, laboratory and problem-solving skills to bedeveloped; (e) teaching competencies to be developed; (/) a set of tasks for teachersto undertake; (g) an outline of probable conceptual difficulties and misconceptionsamong students; (h) an outline of teaching strategies; (i) a list of useful books,research articles, films; (j) questions, problems, and answers on the topic. The majoremphasis of these modules is on the development of competence through a series oftasks to be performed by the teachers. Two achievement tests also form part of thesemodules, to assess competence in knowledge, understanding, application, processand problem-solving abilities.

Development of modules

An analysis of content was carried out and the concepts, laboratory, process andproblem-solving skills, and teaching competence which could be developed usingthe content were identified. A set of tasks to be performed by the intending teacherswas specified. For example, module 1 contained 32 tasks including the identificationof concepts, process and problem-solving skills, concept mapping in the preparationof unit and lesson plans, learning activities, the identification of misconceptions, theuse of physical analogies, applications of the concepts, and assessment. Thedevelopment of competence was to be achieved through the successful completion ofthese tasks by the intending teachers. Relevant information and references for theparticular task were given in the task itself and the intending teachers were requiredto read the reference articles as part of the task. The related literature on the teachingand learning of chemical equilibrium was collected by referring to internationaljournals on chemical and science education. The approach followed by majorcurriculum development projects at senior secondary level (Cotton et al. 1973, Bucat1984, Stokes 1984), together with some standard textbooks (Dickerson et al. 1984,Atkins 1986) on general chemistry at undergraduate level, were used in thesemodules. The relevant research articles and textual matters were summarized andused in the modules in a sequential order based on the content topics. Teachingstrategies on the development of the various concepts were also outlined.

The outlines of the three modules are presented in this paper in the followingsequence:

Module 1: qualitative aspects of chemical equilibrium.Module 2: quantitative aspects of gaseous and ionic equilibria.Module 3: quantitative aspects of solubility, acid-base and redox equilibria.

Module 1

The concept of an equilibrium state and how it can be altered is developed. Theapplication and the danger of the incorrect use of Le Chatelier's principle arediscussed. The teacher should first prepare the content points for the unit and assessthe background knowledge of the students. A number of experiments which may be

Dow

nloa

ded

by [

Stan

ford

Uni

vers

ity L

ibra

ries

] at

17:

30 1

0 O

ctob

er 2

012

THE TEACHING OF CHEMICAL EQUILIBRIUM 357

used either for teacher demonstrations or learning activities are outlined. Elevenprocess skills at the knowledge, understanding and application level in the cognitivedomain, which can be developed through this module, and the strategies fordeveloping these skills are suggested. The laboratory skills and problem-solvingskills (Ashmore et al. 1979) which could be developed through various units are alsogiven. Thirteen teaching competencies ranging from the planning of instruction, theorganization of learning activities, and classroom discussion, to the development ofprocess and problem-solving skills, and an awareness of the possible conceptualdifficulties and misconceptions of the students, are outlined. Concept mappingdescribed by Novak and Gowin (1980) and used by Gussarsky and Gorodetsky(1988) is suggested to the teachers. A number of physical analogies to clarify theconcepts of equilibrium are given, for Johnstone et al. (1977) reported that incorrectphysical analogies lead students to believe in the left and right side compartmen-talized view of chemical equilibrium. Hence, analogies which are liable tomisinterpretation were avoided.

Johnstone et al. (1977) and Hackling and Garnett (1985, 1986) reported theexistence of many misconceptions and conceptual difficulties among grade 11 senior-secondary-school students in different areas of equilibrium - 50% of the students atsenior secondary level thought that at equilibrium the concentrations of reactantsequalled the concentration of products; 43% of the students had the misconceptionthat, when the concentration of a reactant is increased for a reaction at equilibrium,the rate of the reverse reaction is decreased. Similarly, 57% of the students believedthat when the temperature of an exothermic reaction at equilibrium is increased, therate of the forward reaction is decreased. Teachers are expected to utilize the resultsfrom such research studies, and to do so effectively, to avoid the development ofmisconceptions in these areas.

Some very interesting articles on the merits and demerits of Le Chatelier'sprinciple have been published in recent years. Allsop and George (1984) and Goldand Gold (1984, 1985) have argued that the principle is vague and ambiguous andsuggested the replacement of the principle by van't Hoff laws on equilibrium.Bridgart and Kemp (1985) also reported on the limitations on the use of theprinciple. Johnstone et al. (1977), and Hackling and Garnett (1985, 1986) havesupported the usefulness of the principle for qualitative predictions, provided thelimitations are spelt out clearly. Many applications (Bucat 1984) of equilibriumprinciples to daily life and environmental issues are suggested, for example, oxygen-ozone equilibrium, equilibrium reactions of haemoglobin in blood with oxygen,geochemical equilibrium, equilibrium between oxygen in the air and dissolvedoxygen in our lungs and in fruits, equilibrium between solid calcium compounds inbones and calcium ions in the blood, storage of hydrogen as titanium hydride.Module 1 also contains lists of films, references and thirty questions.

Module 2

This module mainly deals with the empirical, kinetic and thermodynamic approachto, and problem-solving abilities on quantitative aspects of gaseous, solubility, ionicand acid-base equilibria (Stokes 1984, Dickerson et al. 1984).

Studies by Johnstone et al. (1977), and Hackling and Garnett (1985) indicatedthat the 'rate approach' to equilibrium may create many conceptual difficulties.Moreover, the 'rate approach' to equilibrium is theoretically sound only for

Dow

nloa

ded

by [

Stan

ford

Uni

vers

ity L

ibra

ries

] at

17:

30 1

0 O

ctob

er 2

012

358 RESEARCH REPORTS

elementary reactions and thus truly applicable for a limited number of reactions. It isemphasized that equilibrium law depends on thermodynamics and not on kinetics(Dickerson et al. 1984, Atkins 1986). Undergraduate students have conceptualdifficulties with Gibbs free energy changes, and the direction and spontaneity ofreversible reactions. Many students and teachers are not able to draw the 'Gibbs freeenergy' versus 'extent of reaction' diagram and are not able to appreciate that boththe forward and reverse reactions are spontaneous and that the direction ofspontaneous change is always towards the equilibrium state which has the minimumGibbs free energy (Dickerson et al. 1984, Atkins 1986). This module also aims at thedevelopement of competence in problem solving, following the steps of the problem-solving approach suggested by Ashmore et al. (1979), Dickerson et al. (1984) andAtkins (1986).

Module 3

This module emphasizes the quantitative development of solubility, ionic, acid-baseand redox equilibria from general equilibrium principles (Cotton et al. 1973, Stokes1984, Bucat 1984, Dickerson et al. 1984, Mickey 1981), problem-solving abilities(Stokes 1984, Dickerson et al. 1984), the application of solubility product, ionicequilibria in water, acids and bases (Stokes 1984, Bucat 1984, Kolb 1978),dissociation constants, buffer solution and redox reactions.

Achievement tests

Two paper and pencil achievement tests were developed as part of these modules toassess the knowledge, understanding, application, process and problem-solvingabilities in the cognitive domain of concepts related to the general principles ofgaseous, ionic, solubility, acid-base and redox equilibria. The achievement test onthe qualitative aspects of equilibrium consists of 30 multiple-choice and six short-answer-type test items. The achievement test on quantitative aspects of equilibriumconsists of 18 items, all dealing with problem solving in the areas of gaseous, ionic,solubility, acid—base and redox equilibria. The test items were mostly selected fromstandardized test-item sources such as ACS-NSTA tests, Chem Study achievementtests, published research papers (Johnstone et al. 1977, Hackling and Garnett 1985)and standard texts (Stokes 1984, Bucat 1984, Dickerson et al. 1984). The tests werefurther content-validated by a group of college and school teachers and scienceeducators in chemistry.

Use of the modules with students

Design and procedure

The modules were used by a group of 46 chemistry students, 19 belonging to thephysics-chemistry (PC) group and 27 to the biology-chemistry (BC) group, enrolledin a two-semester content-cum-methodology course in chemistry as part of ascience-teacher education programme at the Regional College of Education,Mysore. One of the authors (ACB) taught the methodology course. The content-cum-methodology course in chemistry was common to both the PC and BC groups.The three modules were used as a part of the course in the first semester. The courseconsisted of two theory classes, each of one hour's duration, and two practice

Dow

nloa

ded

by [

Stan

ford

Uni

vers

ity L

ibra

ries

] at

17:

30 1

0 O

ctob

er 2

012

THE TEACHING OF CHEMICAL EQUILIBRIUM 359

sessions, each of two hours' duration, per week. The semester was of 16 weeks'duration, followed by a further semester and an examination. The 16-week coursecovered all aspects of the theory and practice of teaching chemistry. The modulesonly formed part of the course and were used with the objectives stated earlier in thispaper. All 46 students of this course had earlier studied chemistry for three years as acompulsory subject at undergraduate level. Chemical equilibrium and thermody-namics constitute a major part of the general and physical chemistry courses at theundergraduate level. These students received their undergraduate education indifferent universities in the region and represented the normal range of studentachievement.

A 'pretest-post-test without a control group' design was used in this study. Tests1 and 2 and the semester end examination (test 3) were used to assess the students.The performance of the students was also monitored through the completion ofassigned tasks and group discussion. Tests 1 and 2 each consisted of 30 items of'multiple choice with reasoning' questions, short-answer questions and numericalproblems. These questions were from the content areas of chemical equilibrium in atypical B.Sc. course. The items were selected or designed to assess the abilities of thestudents in the knowledge and understanding, processes, application and problem-solving domains. These tests were also used to identify misconceptions of students inthe different areas of equilibrium. The nature and difficulty level of the two tests(tests 1 and 2) were kept similar. Test 3 was a two-hour written semester-endexamination on content-cum-methodology of the teaching of chemistry. Thisconsisted of five short-answer questions, each question having two parts. There wasone question in each of the areas of designing learning activities and lesson planning,process skills, problem-solving skills, misconceptions and evaluation. The questionswere from equilibrium and other content areas of chemistry. For example, thequestion on process skill was: 'Choose a process skill and suggest a teaching sequenceto develop this skill using a content area other than equilibrium'. The question onproblem solving was: 'What are the stages of problem solving? Solve the givenproblem using the problem using the problem solving approach of Ashmore et al.(J. Chetn. Educ, Vol. 56,1977)'. Test 3 was used to assess the overall competence ofstudents in the methodology of teaching chemistry.

Students enrolled on the course were briefed about the objective and scope of thepresent study. They were also told about the scope, objective and content areas oftest 1. Some model test items were given to the students and they were advised torevise chemical equilibrium from textbooks. Test 1 was administered after twoweeks of this briefing. Test 1 and the performance of students in this test were notdiscussed. As stated earlier, the modules were developed with the objectives offamiliarizing the students with the research work available in the teaching andlearning of equilibrium, and also to use these modules to develop competencies inselected areas. After test 1, each student was given copies of modules 1, 2 and 3, andthe scope and purpose of these modules were explained by the author (ACB) to thestudents. Since the students had already studied chemical equilibrium as a majorunit in their undergraduate chemistry course, no formal lecture on this unit wasarranged.

The students were asked to concentrate first on module 1. Each student was askedto complete a specified number of tasks given in the module within a stipulated timewith the help of module 1 and cited references. They were given the relevant researcharticles and were further advised to read the connected research articles from the

Dow

nloa

ded

by [

Stan

ford

Uni

vers

ity L

ibra

ries

] at

17:

30 1

0 O

ctob

er 2

012

3 6 0 RESEARCH REPORTS

journals of chemical and science education. The author guided the students in thereading and use of these research articles in the college library. As stated earlier,some guidelines and instructions are given with each task on how to perform andcomplete the task. The development of competence is intended to be achievedthrough the completion of these tasks. For example, task 23 of module 1, onpredicting new equilibrium conditions, reads as follows:

Go through the module and references (Allsop and George 1981, Gold and Gold 1984,1985, Johnstone et al. 1977, Bridgart and Kemp, 1985). Identify the limitations of theuse of Le Chatelier principle. Do you consider Le Chatelier principle to be useful forpredicting the direction of a change at equilibrium? If so, suggest a few examples ofapplications of the principle not covered in this module and in the cited references.

At the end of each week discussions in small groups were organized during thepractice sessions on the performance by the students of the assigned tasks. Thissequence was repeated till all the main aspects of module 1 were covered. The sameprocedure was then followed for modules 2 and 3. The use of the modules ranconcurrently with the theory end practice sessions on different aspects of themethodology course. After 14 weeks of the course, test 2 was administered. Thesemester-end examination (test 3) was held at the end of the 16 weeks.

Performance of students

The overall achievements of the students at the start and end of the course are givenin table 1. There was significant improvement in the mean score of both the PC andBC groups between tests 1 and 2. The achievements in test 2 and test 3 were similarfor both groups, although the scope and purpose of these two tests were different.This indicates a high correlation between the development of concept understand-ing, and skills in the development of methodology of teaching chemistry.

The development of competence in the concepts, processes, applications andproblem-solving domains are reflected in the mean scores given in table 2. There wasa significant increase in the mean score of students in both groups in all thecompetence domains by the end of the course. This seems to reflect the usefulness ofthe modules in the development of these competencies. However, it must be notedthat the mean scores were not very high. The development of excellence incompetence, though very desirable, remains a challenging proposition.

The extent of students' misconceptions in the areas of rate and equilibrium at theentry and exit points of the course are given in table 3. The data indicate that a verylarge percentage of students had misconceptions in these areas particularly at thestart of the course. Typical misconception were (a) large values of an equilibriumconstant imply a very fast reaction; (b) increasing the temperature of an exothermic

Table 1. Achievements at entry and exit levels.

Group

PCBC

Number

1927

Entry level(Test 1)

33-828-7

Mean score (%)

Exit(Test 2)

63-5590

level(Test 3)

64-0600

Dow

nloa

ded

by [

Stan

ford

Uni

vers

ity L

ibra

ries

] at

17:

30 1

0 O

ctob

er 2

012

THE TEACHING OF CHEMICAL EQUILIBRIUM 361

Table 2. Competence in different domains.

Competence domains

Knowledge andunderstanding

Processes

Applications

Problem solving

Group

PCBC

PCBC

PCBC

PCBC

Mean score (

Entry level(Test 1)

30-417-3

31-638-4

22-225-6

220200

°/o)

Exit level(Test 2)

55-8540

58-359-2

500490

55-052-0

Table 3. Extent of misconceptions.

Area

Rate and equilibrium

Predicting equilibriumconditions

Group

PCBC

PCBC

Mean misconceptions (%)

Entry level(Test 1)

66163-8

56-654-3

Exit level(Test 2)

29-730-4

29-4330

reaction would decrease the rate of the forward reaction. This misconception is dueto the wrong use of the Le Chatelier principle to predict rate and thus a confusionbetween the rate and extent of a reaction. Similar misconceptions have been reportedby Hackling and Garnett (1985); (c) the Le Chatelier principle could be used topredict equilibrium constant. Students are not able to appreciate that the LeChatelier principle is only limited to qualitative information about equilibrium.There was a significant reduction in the level of misconceptions at the end of thecourse and this seems due to the exposure of these students, through these modules,to the various research articles on misconceptions and to the discussions in themodules. However, it must be noted that about 30% of the students still hadmisconceptions in these areas despite such discussions and exposure. This furtherstrengthens the fact that the removal of misconceptions is an extremely difficult andchallenging task (Bodner 1986).

Conclusion

Three modules on the teaching of chemical equilibrium were developed as resourcematerials for a content-cum-methodology course in chemistry for intendingteachers. These modules could also be used as a part of a general chemistry course atthe senior secondary and tertiary levels, for the teaching of chemical equilibrium.

Dow

nloa

ded

by [

Stan

ford

Uni

vers

ity L

ibra

ries

] at

17:

30 1

0 O

ctob

er 2

012

3 6 2 THE TEACHING OF CHEMICAL EQUILIBRIUM

The modules deal with the qualitative and quantitative aspects of gaseous, ionic,solubility, acid-base and redox equilibria. Relevant research articles on the teachingand learning of chemical equilibrium, together with science-education research onmisconceptions, conceptual difficulties and teaching strategies, have been in-corporated in these modules for the benefit of intending and practising teachers. Themajor emphasis of these modules is on the development of teaching competence andskills, to be acquired through the completion of a number of tasks, by the intendingteachers. The modules were tried out with a group of 46 chemistry students of amethodology course in chemistry. Significant improvement in the competencedomains of knowledge and understanding, process skills, problem-solving skills andapplications was achieved by the students through the use of these modules. Themodules also helped the students to reduce many misconceptions in the areasrelating to rate and equilibrium and prediction of equilibrium conditions.

References

ALLSOP, R. T. and GEORGE, N. H. 1984, Le Chatelier-a redundant principle. Education inChemistry, vol. 21, pp. 54-56.

ASHMORE, A. D., FRAZER, M. J. and CASEY, R. J. 1979, Problem solving and problem solvingnetwork in chemistry. Journal of Chemical Education, vol. 56, pp. 377-380.

ATKINS, P. W. 1986, Physical Chemistry (3rd ed.) (Oxford University Press, Oxford), ch. 10.BODNER, G. M. 1986, Constructivism: A theory of knowledge. Journal of Chemical Education,

vol. 63, pp. 873-877.BRIDGART, G. and KEMP, H. 1985, A limitation on the use of Le Chatelier's principle,

Australian Science Teachers' Journal, vol. 31, pp. 60-62.BUCAT, R. B. (ed.) 1984, Elements of Chemistry, vol. 2 (Australian Academy of Science,

Canberra), pp. 676-751.COTTON, F. A., DARLINGTON, C. L. and LYNCH, L. D. 1973, Chemistry-An Investigative

Approach (Houghton Miflin, Boston), chs. 22-23.DICKERSON, R. E., GRAY, H. B., DARENSBOURG, M. Y. and DARENSBOURG, D. J. 1984,

Chemical Principles (4th ed.), chs. 4, 5, 15, 16 (Benjamin, New York).GOLD, J. and GOLD, V. 1984, Neither Le Chatelier's nor a principle. Chemistry in Britain,

vol. 20, p. 802.GOLD, J. and GOLD, V. 1985, Le Chatelier's principle and the laws of van't Hoff. Education in

Chemistry, vol. 22, pp. 80-82.GUSSARSKY, E. and GORODETSKY, M. 1988, On the chemical equilibrium concept: constrained

work associations and conception. Journal of Research in Science Teaching, vol. 25,pp. 319-333.

HACKLING, M. W. and GARNETT, P. J. 1985, Misconceptions of chemical equilibrium.European Journal of Science Education, vol. 7, pp. 205-214.

HACKLING, M. W. and GARNETT, P. J. 1986, Chemical equilibrium: learning difficulties andteaching strategies. Australian Science Teachers' Journal, vol. 31, pp. 8-13.

JOHNSTONE, A. H., MACDONALD, J. J. and WEBB, G., 1977, Chemical equilibrium andconceptual difficulties. Education in Chemistry, vol. 14, pp. 169-171.

KOLB, D. 1978, Acids and bases. Journal of Chemical Education, vol. 55, pp. 459-464.MICKEY, C. D. 1981, Using the equilibrium concept. Journal of Chemical Education, vol. 58,

pp. 56-59.NOVAK, J. D. and GOWIN, D. B. 1984, Learning how to learn (Cambridge University Press,

Cambridge, UK).STOKES, B. J. (ed.) 1984, Revised Nuffield Advanced Science: Chemistry. Students' Book II,

Topic 12, and Teachers' Guide II, Topic 12 (Longman, London).

Correspondence

A. C. Banerjee, Department of Science, Regional College of Education, National Council ofEducational Research and Training (NCERT), Mysore-570 006, Karnataka, India.

Dow

nloa

ded

by [

Stan

ford

Uni

vers

ity L

ibra

ries

] at

17:

30 1

0 O

ctob

er 2

012