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Aust. J. Ed. Chem., 2002, 59,
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Aust. J. Ed. Chem., 2002, 59,
Introduction
The Australian Journal of Education in Chemistry publishes refereed articles contributing to education in Chemistry.Suitable topics for publication in the Journal will include aspects of chemistry content, technology in teaching chemistry,innovations in teaching and learning chemistry, research in chemistry education, laboratory experiments, chemistry ineveryday life, news and other relevant submissions.
Manuscripts are peer reviewed anonymously by at least two reviewers in addition to the Editors. These notes are a briefguide to contributors. Contributors should also refer to recent issues of the Journal and follow the presentation therein.
Articles
Articles should not exceed six pages in the printed formincluding tables illustrations and references - ca. 5000words for a text only document. Short, concisely writtenarticles are very welcome. Please use headings andsubheadings to give your article structure.
1. We prefer to handle all submissions electronically. Ourpreference is for Microsoft Word files in Mac format.However, you can send files from any commonWindows, DOS or Macintosh word processor.
2. On another separate page provide an abstract of 50 to100 words;
3. All photographs should be scanned and saved in JPEGformat.
4. All chemistry structures, and schemes should followthe guidelines set for ACS publications. It is preferred
Guide for contributors to the Australian Journal of Education in Chemistry
that Schemes, Tables etc be arranged to fit in a column7 cm wide, although full page width will be accepted.
Reference Styles
AusJEC reference styles are based on the most recentedition of the Publication Manual of the AmericanPsychological Association OR the Journal of ChemicalEducation.
Copyright
Your manuscript should not have been published alreadynor should it have been submitted for publicationelsewhere. If AusJEC publishes your manuscript then itwill become the copyright of the Royal AustralianChemical Institute. The RACI will, however, allow youto use the contents of your paper for most reasonable non-commercial purposes.
Editors
Robert Bucat,Department of Chemistry,University of Western Australia,35 Stirling Highway, Crawley WA 6009, Australia.Email: [email protected]: (+61)(8) 9380 3158Fax: (+61)(8) 9380 3432
Mauro MocerinoDepartment of Applied Chemistry,Curtin University of Technology,GPO Box U 1987, Perth WA 6845, Australia.Email: [email protected] (+61)(8) 9266 3125Fax (+61)(8) 9266 2300
AusJEC TeamDavid TreagustScience and Mathematics Education Centre,Curtin University of Technology,GPO Box U1987, Perth WA 6845, Australia.Email: [email protected]: (+61)(8) 9266 7924Fax: (+61)(8) 9266 2503
Business Manager
Kristy BlythDepartment of Applied Chemistry,Curtin University of Technology,GPO Box U 1987, Perth WA 6845, Australia.Email: [email protected] (+61)(8) 9266 7269Fax (+61)(8) 9266 2300
All manuscripts should be sent to Mauro Mocerino
AusJEC Reviewing PanelGeorge M. Bodner, USAGlen Chittleborough, AustraliaDeborah Corrigan, AustraliaGeoffrey T. Crisp, AustraliaOnno de Jong, The Netherlands
Kitty Drok, AustraliaLoretta L. Jones, USAFaan Jordaan, South AfricaScott Kable, AustraliaBob Morton, AustraliaJohn Oversby, U.K.
W (Bill). P. Palmer, AustraliaMarissa Rollnick, South AfricaJanet Scott, AustraliaRoy Tasker, AustraliaTony Wright, New ZealandBrian Yates, Australia
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Aust. J. Ed. Chem., 2002, 59,
From the Australian Physical Chemistry EnhancedLearning in Laboratories (APCELL) program, the paperby Barnett describes how students can construct their ownsimple sucrosemeter using a He-Ne laser and a hollowequilateral prism. Diffraction of the laser beam by sugarsolutions placed in the prism can be calibrated to measuresucrose concentration. Apart from providing an experienceof instrumentation even at the first-year level, it is claimedthat this transparent apparatus can enable students torecognise the function of each component - unlike mostof today’s ‘black-boxes’. Furthermore, it providesopportunities for critical evaluation of the strengths andlimitations of the instrument and its design, and todistinguish the limitations from human sources of error.In fact, this critical evaluation of the simple instrument -usually not possible in more sophisticated instruments - isclaimed to be one of the most significant advantages ofthe sucrosemeter.
Lim discusses another experiment which is an outcomeof the APCELL range. This experiment investigates,spectrophotometrically, the kinetics of oxidation catalysedby the enzyme o-diphenol oxidase, as well as the kineticswhen there is a competing reaction due to the presence ofan inhibitor such as p-nitrophenol or cyanide. This canserve two functions: to relate physical chemistry to abiological ‘real world’ situation, as well as to provide amore complex system than traditional kineticsexperiments, with many levels of challenge for students.
Confusion over conception of the mole as a number or asa means of comparing one chemical amount with anotheris addressed by Morikawa and Newbold. In this ratheranalytical paper, they develop the concept of one-to-onecorrespondence between elementary entities. They claimthat this can clarify the meaning of the dimension ‘amount
In this issue ……….
of substance’, and suggest a modification of the IUPACdefinition.
Beasley and Ocampo present an important paper in thesetimes of pressure to improve teaching at the tertiary level.The paper reports on the challenges faced by a group ofprofessors of chemistry and chemical engineering inArgentina who undertook a professional developmentcourse based on analysis of their own teaching practices.The action learning model of the course used a cycleinvolving reflection upon four influences: publicknowledge, professional practice, worldview and praxis.The course seems to have been successful in raising self-awareness of changes that the participants might adopt.However, investigation two years on showed that theintended courses of action had not been ‘institutionalised’,largely because of perceptions of external constraints.
In a chemistry education research paper, Head and Bucatreport on an investigation of the three-dimensionalvisualisation abilities of tertiary chemistry students andstaff. Participants were given tasks involving mentalmanipulation of molecular structures, such as recognisingenantiomeric relationships between drawings ofmolecules. Student abilities vary widely. Moreinterestingly, and perhaps more significantly, it was shownthat a wide range of approaches to the tasks were used,and each person consistently employs an idiosyncraticapproach. They point to the potential problem that anexplanation used by a lecturer is necessarily at odds withthe approach of at least some students.
Duggan reviews the book Carbohydrates: The SweetMolecules of Life, authored by R. V. Stick (AcademicPress, 2001) and Mitchell presents another interestingdiscussion in his column The Word on Chemistry.
RACI Chemical Education Division Standing Committee -Contact Details.
Mauro Mocerino, Chair, [email protected] Head, Secretary, [email protected] Baddock, Treasurer, [email protected] Klease, Immediate Past Chair, [email protected] van den Ancker, Qld Chemical Education Group Chair, [email protected] Salem, ACT Chemical Education Group Chair, [email protected] Arnold, ACT representative [email protected] Hey, NSW Chemical Education Group Chair, [email protected] Deretic, NSW representative [email protected] Palmer, NT representative, [email protected] Mc Mahon, SA Chemical Education Group Chair, [email protected] Chittleborough, SA representative [email protected] Yates, Tas representative, [email protected] Patti, Vic Chemical Education Group Chair, [email protected] Gordon, Vic representative, [email protected]
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Aust. J. Ed. Chem., 2002, 59,
Editorial
As this volume goes to press, the early bird registrationdeadline for the National Conference of the ChemicalEducation Division of the Royal Australian ChemicalInstitute is here. The conference is at the University ofMelbourne from 30 November till 4 December, andinformation can be obtained at http://www.deakin.edu.au/fac_st/bcs/RACI_ChemEd/Chem_Ed_Nat_Con_2002.html. Let’s hope that we will see lots of people there whodo not necessarily identify themselves primarily with the‘chemical education community’.
Those involved in chemical education – indeed thoseinvolved in chemistry in any way – ought to know that theInternational Union of Pure and Applied Chemistry has inrecent times focussed its activities less through committeework and more through projects with defined objectives.Applications for project funding are open to anybody –not just IUPAC members.
It is perhaps worth listing the general criteria:
IUPAC projects should address one of the goals listed inthe IUPAC Strategic Plan and satisfy at least one of thefollowing key criteria:
• They should be related to the needs of the chemistsin the world, not just in a country or a region.
• They should be related to the role of chemistry for theneeds of mankind.
• They should best be approached by an international
team such as IUPAC can assemble.
And, by way of further definition of what constitutesappropriate projects, IUPAC have published a list ofexamples:
• Studies of problems of international nomenclature,symbols, terminology and conventions, as the needdevelops.
• Large future-oriented projects important for theposition of chemistry in the world or for the needs ofmankind (CHEMRAWN, teaching of chemistry,problems of publications or of computers, mission-oriented programmes, etc.).
• Compilations with critical evaluation of data bestundertaken by an international team, especiallycompilations of interest to the broader internationalchemical community (e.g., solubility data, electrodepotentials). Data compiled from literature withoutcritical evaluation or obtained experimentally in asingle laboratory are less appropriate.
• Unification of “approved” experimental methods (inparticular those related to analytical problems,characterization of materials, etc.), establishment ofstandards and reference materials, recommendationson procedures of interest in many laboratories, indomains where specialized organizations (ISO, EU,NIST) are not active, or in close cooperation withthem.
And further advice:• IUPAC Divisions and Standing Committees should
prioritize their activities to stress those of the greatestimportance with the greatest impact and interest tothe international chemical community.
• Projects which are inappropriate for IUPAC includereview articles, especially those by a single authorthat might ordinarily be published in the existing reviewliterature (Chem. Rev., Angew. Chem., etc.), purelyinformational projects (e.g., surveys of methods ormaterials without critical evaluation), original researchstudies, experimental studies and recommendationsfrom a single laboratory.
These projects offer a golden opportunity to make aworthwhile contribution involving internationalcollaboration. There have been a number of chemicaleducation-based projects which have come to fruition, andit seems that this field is well suited to participate in thisprogram. A list of current project in all areas of chemistry,with links to descriptions and rationales, is available athttp://www.iupac.org/projects/current_projects.html
More details and application procedures can be found atthe IUPAC website
http://www.iupac.org/projects/index.html#info
RBB
The editors invite readers to make contributions to this Journal.
As well as papers submitted for peer review, we welcome any of the following:
• Short papers on chemistry topics or concepts, from an educational perspective
• Reflective papers teaching and learning chemistry – general or specific
• Letters to the editor • Announcements
• News about people or places • Forthcoming events
• Books to review
An invitation
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Aust. J. Ed. Chem., 2002, 59,
Laser-based liquid prism sucrosemeter: An APCELL experiment.*
Vicky Barnett
Department of Chemistry, Adelaide University, Adelaide, SA 5005, [email protected]
The majority of disciplines in science involveinstrumentation to provide meaningful data for a widerange of applications. The automation of many moderninstruments means the user can often obtain reliable dataeasily without requiring an in-depth understanding of theunderlying science. Such automation (including computer-interfaced data acquisition) is extremely beneficial to thescientist and researcher, but can actually detract fromstudent learning in a practical sense as it compels thestudent to rely solely on theoretical knowledge tounderstand potential limitations and overall reliability ofacquired data. Students often have difficulty in achievingthis, particularly when core components of an instrumentcannot be clearly observed.
While the chemistry involved in this experiment is notchallenging (refraction of light as a consequence ofrefractive index), its main benefit is that it reinforces theimportance of critically assessing instrumentation andexperimental design when considering data reliability (asopposed to attributing all error to ‘experimental error’).
The experiment focuses on instrumentation that is entirelytransparent and easily controlled by the student. Theyconstruct their own analytical instrument that has anobservable response signal (visible laser beam diffraction),enabling students to directly recognise the function of eachcore component. Using their instrument to performanalysis of real samples reveals not only the success ofthe instrument but also limitations in its applicability. Forsuccessful analyses, students consider accuracy andprecision of their instrument. This is aided via acomparison of their experimentally obtained data with dataobtained from a commercial instrument as well as literaturevalues. For analyses that were not successful, studentsfurther explore experimental design by consideringmodifications to their set-up that could overcome itscurrent limitations.
Educational Template
Section 1 - Summary of the Experiment
1.1 Experiment Title
Laser-Based Liquid Prism Sucrosemeter.
*The complete documentation for this experiment is freely available on the APCELL web site [www.apcell.org]. It includes the
educational template, a set of student notes, demonstrator notes and technical notes to allow ready implementation into a newlaboratory.
1.2 Description of the Experiment
In this experiment students construct their ownsucrosemeter using a He-Ne laser and hollow equilateralprism. Sugar solutions are placed in the prism and thediffraction of a laser beam through these solutions can bemonitored as a function of concentration, enablingdetermination of ‘real’ unknown solutions (cordial, softdrinks etc.). If available, a commercial refractometer isan ideal addition to the experiment as students can comparethe results of their constructed sucrosemeter to thecommercial one.
The benefits to student learning in this experiment are moreof a general nature than specific to concepts presented bylectures. The fact that real samples are analysed is alwaysa plus to student learning. Technical skills in makingstandard solutions and drawing results from calibrationcurves expose the student to core analytical skills.
Constructing their own apparatus which is simple yetyields accurate results reinforces in students thatinstrumentation and design do not always need to becomplicated or expensive. With continued advances inthe technology of instrumentation as well as interfaceddata acquisition software, it is easy for students to simply‘press a button’ to obtain results without considering thechemistry that occurs within a fully enclosed instrument.The simplicity of the experimental set-up as well as thetransparency of the response signal (visible laser beamdiffraction) in this experiment encourages students toconsider ‘cause and effect’ components of instrumentation.Students critically analyse experimental design by probingboth strengths (reliable determination of refractive indicesand sucrose concentrations) and limitations of theirexperimental set-up (analysis of dilute samples andsamples of complementary colour to the laser beam cannotbe reliably made without modifications to the design and/or sampling). Comparison of direct readings of diffractionangles to calculated angles also encourages students toassess accuracy over simplicity when considering datacollection methods (for this experiment, direct readingsof deflection angles gives poor accuracy, whereascalculated angles yield great accuracy due to relativelysmall error propagation).
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1.3 Course Context and Students’ RequiredKnowledge and Skills
This experiment has little direct linkage to general coursematerial in Physical Chemistry, unless a componentregarding refraction of light through prisms / solutions,Snell’s Law, simple laser chemistry etc. is incorporated.Indirectly, this experiment can enhance a student’sconfidence in his/her own ability to simplify andcomprehend new concepts taught in Physical Chemistry.(New concepts in Physical Chemistry can be difficult forstudents to grasp if the language and mathematicalrelationships overwhelm them - this experiment is easilyunderstood, and the associated mathematics is easilyapplied.)
Minimal prior knowledge is required by students tosuccessfully conclude this experiment. Advantageousskills to have are competency in using volumetrictechniques / glassware, basic knowledge of light refractiontrends and adeptness in constructing and applyingcalibration curves.
The experiment as presented here is undertaken by oursecond year students, however I feel that it is simpleenough to be adapted as a first year practical.
1.4 Time Required to CompletePrior to Lab 30 min - 1 hr (reading)In Laboratory 2 – 3 hrsAfter Laboratory 2 – 3 hrs (plotting data, analysing
results, calculations, report writing)
1.5 AcknowledgmentsThis experiment was adapted from “Narayanan, V.A. &Narayanan, R. Laser-based Liquid Prism Sucrosemeter –A Precision Optical Method to Find Sugar Concentration.J. Chem. Ed., 74 (2), 1997”.
1.6 Other CommentsIn my opinion this experiment is not very challenging whencompared to other experiments offered by us at secondyear level. Despite this, I find it works very well in thelaboratory as it incorporates several analyticalmethodologies common to many experiments. When the
students are exposed to the second year laboratories (esp.physical chemistry) for the first time, they are oftenoverwhelmed by the instrumentation, equations involvedin analyses and graphing techniques that they have hadlittle prior experience in. This experiment enables studentsto “re-focus” on many common features of experiments(calculations, using equations, linearity relationships andsubsequent calibration curves, error analysis) in astraightforward easy to follow way. I have found thatstudents sometimes gain a better perspective on the subjectarea as a whole when they are able to “practice” commonfeatures (such as graphical analyses) using a protocol thatis easy to follow and understand, and has very littleprospect of failing to yield reliable results.
As a learning tool this experiment is most effective if it isextended to incorporate scenarios where the design yieldsaccurate and reliable data as well as scenarios whereaccuracy is not possible without modifying the design and/or approach. In general, students often attempt to designatepoor results to ‘experimental error’ (error in pipetting,human error in weighing etc.). In many cases such sourcesof error cannot significantly account for deviations inresponse signals (for example if the concentration rangeis beyond an instruments detection limits, or if specifiedconditions for optimal output are not maintained). It istherefore imperative that students develop the ability tocritically assess experimental limitations and distinguishthese from sources of error. Addressing limitations in theirexperimental design and exploring ways to overcome thesecan precipitate such critical assessment in students.
It is intended to incorporate comparison of student’s resultsto results they obtain when using a commercialrefractometer. The attached experimental write-up has notbeen modified to incorporate this as we are yet to trial therefractometer we have available to us.
On a further note, it is a reliable simple analyticalexperiment that can be very cheap to set-up and maintain.Commercial sugar and cordials are the only consumableexpenses; the He-Ne laser could be replaced with acommercial laser pointer; the hollow prism could beconstructed using microscope slides.
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Section 2 – Educational Analysis
Learning Outcomes
What will students learn?
Process
How will students learn it?
AssessmentHow will staff know students have
learnt it?How will students know they have
learnt it?
Theoretical and Conceptual Knowledge
The importance of criticalappraisal of theories andconceptual applicability.
By observing a) successful outcomes oftheir experimentation as well as b)limitations in the applicability of theirset-up:a) Students use theoretical relationships tocalculate refractive index values ofsamples from experimental measurements.By comparing their results to literaturevalues (and/or measurements from acommercial refractometer), students cansee the accuracy of their experimentaldesign.
b) By considering and observing scenarioswhere the experimental design would notbe applicable in the current set-up (dilutesolutions and complementary colouredsolutions to laser beam) encouragesstudents to critically address conceptsrather than to simply accept them.
Accuracy of experimentally determinedvalues as compared to theoreticallyobtained values.Explanations of reasons for observedlimitations of the experiment.
Discussions of further potentialapplications of the experimental design(instigated by questions posed in themanual), emphasising consequentiallimitations and ways to overcomethese.
These points are assessable via thesubmission of a written report, as wellas oral communication with thedemonstrator at the conclusion of theexperiment.
Scientific and Practical Skills
Ability to collate,correlate, display, analyseand report observations.
By recording experimentally obtained dataand then using this data to determinestandard properties of their samples(refractive index, concentration):
Students clearly see the response signalthey measure (laser beam deflection).They recognise trends in this responsesignal to sugar concentration (a linearrelationship) and can hence use theirresults to determine sugar concentrationsof real samples.
By applying experimental data totheoretical relationships (from themeasured response signals, deviationangles are calculated which are then usedto calculate refractive index values) andcomparing values to literature values,students can see further applicability totheir experiment design than simpleconcentration analysis.
Students must collate a written reporton their experiment, which is based ona standard format which is clearlyoutlined in their manual. This is aweekly requirement in our laboratories,so students become aware that they areeffectively mastering this requirementas it becomes quicker and easier forthem to collate their reports as theirexperience grows. Assessment islargely biased towards the student’sability to describe the relevance /theory of the experimentation, as wellas their ability to discuss thesignificance of their results.
Each practical report is marked by onedemonstrator only, so the demonstratorcan obtain a general idea of theexperiment’s success (in lieu of studentcomprehension as well as accuracy inexperimental output) due to repetitiveassessment over the course of onesemester.
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Ability to considerlimitations as well assuccessful applications ofexperimentation.
As well as any sample a student maychoose, they also analyse providedsamples that can be reliably analysedusing their experimental design (mostcordials, soft drinks, etc.). Other samplesare also analysed that cannot yield reliableresults without modifying theirexperimental design (e.g. cordial ofcomplementary colour to the laser beam,and solutions that fall outside of thecalibration range that can beaccommodated by the design). Studentstherefore directly observe strengths aswell as limitations of their experimentaldesign.
By explaining why one sample wasunable to be analysed whereas all othersamples were successfully analysed.Questions posed in the manual guidestudents to explain reasons for theexperimental limitation they observed(as well as others) and assist students toconsider modifications of theexperimentation that could overcomelimitations.
This is assessed via verbalcommunication as well as discussionspresented in the student’s writtenreport.
Understanding theoperation ofinstrumentation.
The transparency of the cause and effectresponse (visible laser beam refraction)being measured as a function ofconcentration enables the student to seeclearly the operation of theinstrumentation.
Comparing their experimental results toresults obtained using a non-transparentcommercially obtained refractometerencourages students to translate theirdirect observations to otherinstrumentation, realising that the majoritycontain core components that induce adetectable affect on a sample which can beconverted to meaningful data.
As above, orally and via writtenreports.
Ability to present reportsin appropriate formats.
By constructing a written report onconclusion of their experiment, following(if desired) clear guidelines presented intheir manual.
Assessment of their written report isbased not only on content, but also onappropriate presentation adhering tostandard form (e.g. abstract, aim,introduction, experimental, results,discussion, conclusion, references).
Generic Skills
Problem solving: abilityto apply problem solvingin familiar and unfamiliarsituations, and to displaythe capability of rigorousand independent thinking.
After observing predictable and reliable trendsin the response signal to various standardsolutions (variation of response is proportionalto sugar concentration), students are given anunknown solution to measure in which theresponse signal cannot be observed. Studentsare not forewarned of this, and thereforeundergo a more complete ‘trouble-shooting’process. For some students, this is a quickprocess as they realise that the conjugatecoloured solution absorbs the laser beam.Other students repeat their sampling andmeasurements of the ‘wayward’ unknown,double checking procedures used by theirpartners. After observing a failure to obtain aresult after such repetition, students must thencritically appraise their experimentation todetermine why the initial successful applicationof their experiment has failed. Most studentsrealise (sooner or later) what is happening withlittle or no prompting from the demonstrator.
By addressing questions posed in themanual as well as explainingexperimental limitations, students willhave successfully extended themselvesregarding problem identification andsolving. Demonstrators will be able toassess this process by observing thestudent’s approach to identifyingexperimental limitations and ways inwhich to overcome them (as well asexplanations to questions posed in oralcommunication and the written report).
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Working with others:one-to-one and in teams,understanding andresponding to thedemands of the task andworking effectively toachieve a shared goal,coping with set backs.
The experiment is typically undertaken inpairs, with sharing and / or division of tasksbeing established by the studentsthemselves. When limitations of theexperimental design (after obvious success)are encountered, the students work togetherto discover why, with resolution often beingachieved prior to consulting thedemonstrator. On occasion, students willquestion each other’s technique beforequestioning the experimental design or ademonstrator. Teamwork can be enhancedwhen the students determine that neitherthey nor their partner have erred.
Teamwork is noticed as being effectiveduring the course of the experiment, byobserving the students setting up theequipment, as well as running theexperiment and analysing andinterpreting data, as well as addressingquestions posed in the manual. Poorteamwork can sometimes be noticed ifa student does not have all relevantmeasurements in their written reportafter the laboratory session (e.g.accurate masses of sugar weighed forpreparation of standard solutions).Oral assessment at the conclusion ofthe experiment is usually performed bythe demonstrator on each group ratherthan individual students. During thistime, the demonstrator discusses pointsof the experiment with each student inthe group.
Critical analysis:evaluating relevance andrelating knowledge to thereal world.
Students critically analyse theirexperimental set-up by comparingcalculated values to theoretical values (andcommercial instrumentation if available).They consider the accuracy of their method,and address limitations (bothexperimentally determined as well ashypothetical situations directly relevant torealistic scenarios). The students measureconcentrations of sugar in real ‘everyday’samples.
Assessed as per methods alreadydiscussed.
Life-Long Learning: thecapacity for andcommitment to life-longlearning.
Students learn this skill as they are directlyin control of the entire experimentationthemselves (from setting it up to concludingreliable information). They set up their ownapparatus and question its application incontexts where success is evident as well asin situations where success requires furthermodifications.
This is normally evident in the studentswritten report (usually written duringthe week following the experiment). Astudent who has mastered thisparticular skill will normally present areport on successful experimentation,with suggested modifications thatwould extend its applicability.Students who require furtherexperience in attaining this skill willoften report limitations to theexperimental design rather thanextended modifications to theinstrumentation.
3.1 Did this experiment help you to understand thetheory and concepts of the topic? If so, how, or ifnot, why not?Yes, fairly simple concept. The intro & theory sectionsaid everything involved.
3.2 How is this experiment relevant to you in termsof your interests and goals?It’s another good (& simple) example of analyticalchemistry. Lasers are always fun.
Section 3 - Student Learning Experience
3.3 Did you find this experiment interesting? If so,what aspects of this experiment did you find ofinteresting? If not, why not?Yes. I think analysing unknowns was interesting.
3.4 Can the experiment be completed comfortably inthe allocated time? Is there time to reflect on thetasks while performing them?Yes & yes.
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3.5 Does this experiment require teamwork and if so,in what way? Was this aspect of the experimentbeneficial?When taking the angle measurements.
3.6 Did you have the opportunity to takeresponsibility for your own learning, and to beactive as learners?I guess so, if you mean learning from the intro &theory. Graphing and interpreting is always asatisfying end to an experiment.
3.7 Does this experiment provide for the possibilityof a range of student abilities and interests? If so,how?It’s not too challenging (reminiscent of high schoolphysics) – which is nice once in a while.
3.8 Did the laboratory notes, demonstrators’ guidanceand any other resources help you in learning fromthis experiment? If so, how?Lab notes for theory, demonstrator for set up ofequipment.
3.9 Are there any other features of this experimentthat made it a particularly good or bad learningexperience for you?Good – comparison of measured and calculatedvalues.
3.10 What improvements could be made to thisexperiment?None really – maybe just get students to test moreunknowns.
3.11 Other Comments[no responses]
What’s in a formula? - Pedagogical content knowledge
Formulas of elements andcompounds provide informationabout the substances that theyrepresent. For example, He refersto a substance that consists ofmonoatomic molecules, N
2
represents another that consists ofdiatomic molecules and P
4 is the
formula of another that has fouratoms in each of its molecules.Why then don’t we use S
8 to
represent solid sulfur? After all, weuse C
6H
6 for benzene, and not CH.
But C for diamond? Maybe theanswer lies in balancingcomplexity and the amount ofinformation provided by theformula.
Sometimes the information in aformula is hidden unless we havean understanding of the nature ofthe substance. For example,chemists ‘know’ that He, Na and Sido not all refer to substances thatexist as monoatomic molecules.And the formulas SiO
2 and CO
2
may look similar, but they meanvastly different things to the personwith a knowledge of structures. Tobe specific, the formula, SiO
2 for
silicon dioxide - a covalentnetwork substance - is taken tomean that in silicon dioxide thereare twice as many oxygen atoms inthe network as there are silicon
atoms. In a sample of carbondioxide there are twice as manyoxygen atoms as carbon atoms, butthe formula CO
2 provides the
additional information - if youunderstand carbon dioxide to be amolecular substance - that eachmolecule of carbon dioxide has onecarbon atom and two oxygen atoms.In summary, SiO
2 tells us about
relative numbers, but CO2 tells us
about absolute numbers.
Sometimes we use formulas toindicate structural information. Formany compounds, there may bevarious acceptable formulas, eachproviding a different amount ofinformation. For example,benzaldehyde may be representedby either C
7H
6O or C
6H
5CHO. The
first tells us only the composition,while the second providesinformation about the structure ofthe molecules.
But then the formula of sulfuric acidis almost always written as H
2SO
4.
This formula represents thecomposition of the moleculesaccurately, but does it suggest to thenovice that the hydrogen atoms arejoined to the sulfur atom? Giventhat each hydrogen atom is bound toan oxygen atom, is SO
2(OH)
2 a
preferable formula?
An interesting question is how torepresent the formula of ammoniumiron(II) suIfate-6-water (ferrousammonium sulfate hexahydrate).The formula most commonly foundon the labels of bottles isFeSO
4.(NH
4)
2SO
4.6H
2O) - a typical
formula for the ‘double salts’.However, this formula almostimplies that there are twocompounds present: iron sulfate andammonium sulfate. It suggests thathalf of the sulfate ions areassociated with the iron(II) ions andthe other half with the ammoniumions.
A more acceptable view of thestructure of this compound is of alattice containing sulfate anions, andboth iron(II) cations and ammoniumcations - as though half of the Fe2+
ions in an iron(II) sulfate samplehave been replaced by twice asmany NH
4+ ions. So a preferred
formula might beFe(NH
4)
2(SO
4)
2.6H
2O.
Then again, X-ray diffractionstudies on crystals of ammoniumiron(II) sulfate indicate that thewaters of crystallisation are allbound to the iron(II) ions. Soperhaps we should show this in theformula by representation of thehexaquairon(II) complex ion in the
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Aust. J. Ed. Chem., 2002, 59,
Inhibition of the reaction kinetics of the enzyme o-diphenol oxidase:An APCELL experiment.*
Kieran F. Lim
School of Biological and Chemical Sciences, Deakin University, Geelong, Victoria 3217, [email protected]
IntroductionChemical kinetics is a fundamental component ofchemistry. Traditional chemistry-laboratory exercises haveconcentrated on the study of non-biological organic orinorganic reaction kinetics. Historically, these experimentsare chosen for their perceived didactic value — theyusually exhibit simple kinetics, without complicatingfactors — rather than for any “relevance” to the worldoutside the chemistry laboratory. The same lack-of-relevance is applicable to many “traditional” experimentsin other areas of chemistry. Therefore, the fact that studentsare avoiding the study of chemistry (1), should not besurprising.
The aim of this experiment is to investigate the kinetics ofan enzyme-catalysed reaction, and the kinetics in thepresence of an inhibitor (2-15). This relates physicalchemistry to a “real world” application — the action of abiological catalyst, o-diphenol oxidase (oDPO). Betterstudents need to be challenged (16) by extentions to theexperiment, which is easily achieved since the complexityof biological systems offers many avenues for exploration.
Enzyme kinetics is usually described by the Michaelis-Menten model, which can be used to illustrate severalconcepts in the curriculum. The behaviour of enzyme-catalysed reactions is not simply proportional to the powerof the reactant (substrate) concentration [S]. The kineticschanges from being first-order with respect to [S] at low[S], to being zeroth-order at high [S], with non-integerorder at intermediate [S] (3-10). The derivation of theMichaelis-Menten kinetic equations involves use of thequasi-steady-state approximation (3-6). Furthermore, thelaboratory is an opportunity to learn how to handle photo-sensitive reagents.
The original version of this laboratory exercise used p-nitrophenol and cyanide anion inhibitors. Other inhibitors(15), with smaller health and safety risks, can be used: egNaCl (10 mM stock) under the conditions described inthe notes, has been successfully used at Deakin University.
This exercise has the potential to be further developed asan affordable high-school experiment using the browningof mashed raw fruit or potatoes as the enzyme-catalysedreaction and a home-made colorimeter for under $15 (17).
In this configuration, the most expensive items ofequipment or reagents would be a sturdy kitchen knifeand food processor!
AcknowledgementsThe author wishes to thank: Ms Jeanne␣ Leefor introducing him to an earlier version of this experimentand for encouraging and helpful discussions; Dr RobertLearmouth (University of Southern Queensland) for givingpermission for his version of the experiment to be adaptedand developed at Deakin University; Dr J.R.L. Walker(retired, University of Canterbury) for documentation onexperiments using oDPO extracted from mushrooms andbananas, and for a reprint of reference (14); members ofthe APCELL team and undergraduate students at DeakinUniversity for useful feedback and suggestions.
Educational Template
Section 1 - Summary of the Experiment
1.1 Experiment TitleReaction Kinetics. Inhibition of the Enzyme o-DiphenolOxidase
1.2 Description of the Experiment
Chemical kinetics is a fundamental component of physicalchemistry. The aim of this experiment is to investigate thekinetics of an enzyme-catalysed reaction, and the kineticswhen there is a competing reaction due to the presence ofan inhibitor (2-15). This relates physical chemistry to a“real world” application — the oxidation of an organiccompound through the action of a biological catalyst.
1.3 Course Context and Students’ RequiredKnowledge and Skills
The School of Biological and Chemical Sciences at DeakinUniversity has students enrolled in the biology,biotechnology, forensic and wine science streams as wellas the chemistry stream: the physical chemistry unit hasto cater for a wide range of student interests andmathematical skills.
One of the foci of the School is the promotion of the
*The complete documentation for this experiment is freely available on the APCELL web site [www.apcell.org]. It includes theeducational template, a set of student notes, demonstrator notes and technical notes to allow ready implementation into a new
laboratory.
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Aust. J. Ed. Chem., 2002, 59,
interdisciplinary nature of modern chemistry (via“biologically relevant” chemistry) and of modern biology(via molecular biology). Instead of doing a “traditional”kinetics experiment, an enzyme kinetics reaction is studied,also with inhibition via a competing equilibrium (here“competing equilibrium” is used in the usual chemicalsense, meaning alternative pathway).
This kinetics experiment is the third experimental exercise(total of five such experimental exercises) done duringthe semester-long 2nd year physical chemistry laboratory.
• Students are expected to have knowledge of 1st yearkinetics and 1st year equilibrium topics.
• Prior to the start of this laboratory exercise, studentshave been introduced to the use of a spreadsheetpackage. Nevertheless, students are told that use of aspreadsheet is part of the computer laboratorycomponent of the exercise and should consult theirdemonstrator if they encounter difficulties.
• Students are not expected to have knowledge ofkinetics or equilibrium topics at 2nd year level. Anappendix introducing enzyme kinetics is included inthe student notes for those students who are unfamiliarwith the topic.
Some students may have encountered enzyme kinetics inBiochemistry during the first semester of second year.Those students would have done a biochemistry laboratoryexercise on enzyme kinetics (Michaelis-Menten kinetics),but not an exercise on inhibited enzyme kinetics. Overhalf the students attempting this laboratory exercise wouldnot have attempted the biochemistry laboratory exercise.
1.4 Time Required to CompletePrior to Lab 1 hour readingIn Laboratory 2 hours “wet” laboratory and
2 hours “dry” laboratory for analysisof results
After Laboratory 2-3 hours report writing
1.5 ProvidenceThe original source of this experiment is unknown.
Kieran Fergus Lim (Deakin University) and RobertLearmouth (University of Southern Queensland) both haveversions of this experiment derived from an experimentrun by Robert Learmouth when he was at University ofNew England (c.␣ 1990). Robert Learmouth has givenpermission for the experiment to be adapted and used.
Verbal tradition at University of New England suggeststhat the experiment came from the University of Sydney(c.␣ 1960s? 1970s?), but current Sydney staff (c.␣ 2000) haveno knowledge of the experimental exercise.
Many similar experiments (mostly on un-inhibitedMichaelis-Menten kinetics) have been published in theliterature: for example, (14,15,18-23).
1.6 Other CommentsJ.R.L. Walker (retired, University of Canterbury, NewZealand) has run a similar experiment using the sameenzyme extracted from mushrooms and bananas.Extraction from other fruit is also possible. The Universityof Canterbury experiment usually used the kinetics todetermine comparative concentrations of o-diphenoloxidase enzyme (oDPO or tyrosinase) in different partsof the mushroom, and hence was not a kinetics experimentas such. Walker has published a paper on the inhibition ofo-diphenol oxidase by phenolic acids (14) and gives a listof inhibitors of o-diphenol oxidase activity in (15).
In the student notes, p-nitrophenol and cyanide anioninhibitors were described for historical reasons. One ofthe referees has pointed out that use of these inhibitorsposes health and safety risks: we have since used NaCl(10mM stock) as an inhibitor: other inhibitors of o-diphenol oxidase activity␣ (15) are also possible.
ionic lattice, and use the formula[Fe(H
2O)
6](NH
4)
2(SO
4)
2.
But we have to be careful. Howshould we represent the formulaof nickel chloride-6-water whosecomposition is represented byNiCl
2.6H
2O? In view of what has
been said above, we might thinkthat the formula [Ni(H
2O)
6]Cl
2
provides structural information.Well it would - but incorrectinformation! Crystallographerstell us that each nickel ion formsa complex with four watermolecules and two chloride ions.The other two water molecules in
the lattice are not directly bound tothe nickel ions. So perhaps[Ni(H
2O)
4Cl
2].2H
2O is the most
appropriate structural formula.
Where do we stop? Presumably ourbest guide is provided by thepurpose for which a formula isbeing used.
The really important message in thisdiscussion is that how we interpretthe formula of a substance usuallydepends on prior knowledge aboutthe substance. And it is often thecase that students don’t have theknowledge that allows them to
interpret formulas in the same waythat experts do. And perhaps it’s notsurprising that sometimes they areconfused!
RBB
13
Aust. J. Ed. Chem., 2002, 59,
Section 2 - Educational Analysis
Learning Outcomes
What will students learn?
Process
How will students learn it?
AssessmentHow will staff know students have
learnt it?How will students know they have
learnt it?
Students must understand and usethe relationship between thetransmitted light intensity of a‘blank’ and the transmitted lightintensity of the sample, in order todetermine the absorbance of thesample using a single-beamspectrophotometer. These three fundamental concepts
underpin the entire exercise
Students are able to convert theirlight intensity (transmittance or“absorbance”) measurements intoreaction rates
Students must understand thedefinition of reaction rate in order tomeasure rate (in arbitrary units) bythe change in concentration (inarbitrary units) over time.
Students will measure kinetics associated with a food stuff
Students should appreciate thatreaction kinetics is applicable to real-life systems, not just systemsinvolving methyl isocynide and other“textbook” systems.
Use of the Michaelis-Mentenreaction kinetics.
Students are able to see to see that arate versus reactant (substrate)concentration curves from linearproportionality (first order) to beingconstant (zero order) at highreactant concentration.Staff will know from the students’discussion of the Michaelis-Mentenreaction kinetics.
Theoretical and Conceptual Knowledge
Students must understand and applythe Beer-Lambert Law in order touse absorbance to measureconcentration (or at leastconcentration in arbitrary units).
Students should appreciate thatcomplicated reaction mechanisms(like the Michaelis-Mentenmechanism) will give rise to non-integer reaction orders.
Students should be able to exercisejudgement about what is (or is not)relevant in the context of theexercise, judgement about what is(or is not) significant in the contextof the exercise, and judgementabout what is (or is not) importantin the context of the exercise.
Students must decide what toinclude or omit from a formalwritten report. They are given thedemonstrator’s assessment andfeedback pro␣ forma. They areencouraged to seek help from thedemonstrator.
There must be sufficient data,details and discussion in the mainbody of the report, so that a student(classmate) who has doneeverything as the student writer,except this exercise (or this unit),can understand the report.
14
Aust. J. Ed. Chem., 2002, 59,
Students prepare sample solutionsand use the spectrophotometer tomake measurements.
Spectrophotometer will be withinthe expected ranges (ie not off-scale).Students will record consistentmeasurements.Linear Lineweaver-Burk plots willresult from proper use of theinstrument when the proper “blankcorrections” have been made.
Students will protect reagents andsample solutions from light.
Students will record measurementsat the end of the exercise (eg test-tubes 10, 11, 12) that are consistentwith measurements at the start ofthe exercise (eg test-tubes 1, 2, 3).
Students will use a spreadsheetpackage to collate, display, andanalyse observed data.
Students will obtain linearLineweaver-Burk plots, similar tothose in the student notes.
Students should be able to operate asimple spectrophotometer.
Students should be able to handlelight-sensitive reagents.
Students should be able to use aspreadsheet package to collate,display, and analyse observed data.
Generic Skills
Students must divide tasks betweenthemselves at different stages of thelaboratory exercise.
Students will complete the allocatedtasks with minimal conflict.
Students should be aware of andconvert between molar (mol␣ L-1)and millimolar (mmol␣ L-1)quantities.
Students should be aware of andconvert between molar (mol␣ L-1)and millimolar (mmol␣ L-1)quantities.
Students are given the opportunityto submit draft reports for comment.Students are encouraged to consulttheir demonstrator on the reportwriting style and use of appropriatecomputer programs
Students will present a formal writtenreport, which satisfies the criteria setout on a assessment and feedbackpro␣ forma.
Students should be able to work inteams, and to plan and manage theirtime effectively.
Students must be able to use andinterconvert units correctly.
Students should (further) developcommunication and generic skills(24,25), including the ability to useappropriate computer programs (26).Note: The semester-long physicalchemistry laboratory program at DeakinUniversity is one of a series of laboratoryprograms specifically intended to fosterreport-writing skills. Students are giventhe opportunity to submit draft reports forcomment. This aspect of the curriculumis not an integral component of the currentexercise.
All of the above knowledge andskills
By preparing a clear, well-structured formal report, studentswill organise their knowledge andunderstanding and to consolidatelearning (27)
Students demonstrate that theirknowledge, skills andunderstanding … satisfy the statedand implied criteria and they havemet [or exceeded] all the otherrequirements …
Note: This criterion is an extract fromthe Faculty guidelines on grading andassessment. It is clearly communicatedto students during the semester and isthe basis for assessment of alllaboratory exercises and assignments.
Scientific and Practical Skills
15
Aust. J. Ed. Chem., 2002, 59,
Explainatory notes to Student Learning ExperienceIn response to student feedback in 1999 and 2000, the exercise was revised (28,29) and presented to the APCELLworkshop (30) in early 2001. The exercise and associated documentation was again revised, incorporating suggestionsfrom workshop participants. The student responses in this section document improvements to the exercise over the last2 years (S1-4, 2000; S5-8, 2001). The version presented here includes further changes in response to the 2001 studentfeedback, and to comments from the APCELL referees. In the following responses, omission of a particular student (egS7 and S8 for question 3.2) indicates that the student did not respond to that particular question.
Section 3 - Student Learning Experience
3.1 Did this experiment help you to understand thetheory and concepts of the topic? If so, how, or ifnot, why not?
S1: Yes, gives practical example in which the observedoccurrences aid understanding.
S2: No, not easy to understand the kinetics. Thereforedidn’t understand final results.
S3: Yes, a little. I got values and I know what these valuesmean but concepts where a little hard to understandat first.
S4: Yes, it demonstrated how Michaelis-Menton kineticscan be applied to enzyme activity.
S5: I personally struggled a little with the concepts andtheory involved. I think this was partly due to myvery limited background in biology/ biochemistry.
S6: Yes, the write-up helped me understand the theory.S7: Yes, it overlapped Biochem A from last term, but in
more depthS8: Yes.
3.2 How is this experiment relevant to you in termsof your interests and goals?
S1: Enzyme kinetics isn’t my major area of interest. Butit is good to be able to understand.
S2: Not very relevant.S3: Not that relevant, but I do think it is interesting.S4: It helps to increase my background knowledge of
reaction kinetics.S5: My planned major is environmental engineering. I
feel some biochem may be useful for me.S6: Kinetics is used extensively for chemistry in
pyrotechnics and explosives development.Note: This student had commented previously (in feedbackfor another exercise) that he wanted a career inpyrotechnics and explosives development.
3.3 Did you find this experiment interesting? If so,what aspects of this experiment did you find ofinteresting? If not, why not?
S1: Yes. understanding the principles behind the prac.S2: Yes, it was interesting to observe the biological
effects of catalysts and inhibitors and the effects theyhave on reactions.
S3: Yes, getting to use “real” food not just chemicals injars was something different.
S4: Yes, it was good to use a potato instead of justchemicals.
S5: I find chemistry work much more interesting whenit has a ‘real world’ relevance. Here we used potatoesand talked about bruising.
S6: Nope, sorry. Didn’t find much at all interesting.
Didn’t appeal to me.S7: In between! It had interesting things and boring
things.S8: Yes.
3.4 Can the experiment be completed comfortably inthe allocated time? Is there time to reflect on thetasks while performing them?
S1: Yes, there is time to reflect as the prac can be coveredquite quickly
S2: Yes, there was enough time to complete the prac butwhen adding the inhibitor in one-minute intervals, itwas difficult to reflect on what was happening.
S3: Yes, we had plenty of time.S4: Yes.S5: Yes & no.S6: Yes plenty of time.S7: Yes.S8: Yes.
3.5 Does this experiment require teamwork and if so,in what way? Was this aspect of the experimentbeneficial?
S1: Teamwork is required to ensure the experiment runssmoothly during analysis section. Working as a teamis very beneficial as it can lead to quick and effectivework.
S2: Not much teamwork was required, only whenrecording absorbances in one-minute intervals wasit better to work with someone. This was beneficialas it allowed timing to be more accurate.
S3: Working in groups is usually more beneficial as youcan discuss what is happening with team membersand it speeds up the prac as you don’t have to do allthe boring pipetting yourself.
S4: Yes, to help understanding.S5: Exp. definitely runs faster when working in a group.S6: Yes. teamwork is needed to get the potato and enzyme
ready in the right time intervals.S7: Yes, teamwork for this experiment was beneficial.S8: Yes — In order to make it a quick and easy
experiment.
3.6 Did you have the opportunity to takeresponsibility for your own learning, and to beactive as learners?
S1: Yes, you have to take responsibility otherwiseunderstanding of the topic will be harder.
S2: No, more focussed on getting good results.S3: Yes, I had to do some research to understand the
concepts.
16
Aust. J. Ed. Chem., 2002, 59,
S4: Yes.S5: Yes, to an extent.S7: Yes.S8: Yes.
3.7 Does this experiment provide for the possibilityof a range of student abilities and interests? If so,how?
S1: Yes, there was a reasonable diversity of elements thatneeded to be understood.
S2: Yes, it incorporates a bit of biology with a bit ofkinetics.
S3: Yes, because it is more Biochemistry / Biologyrelated.
S4: It’s kind of a bit of biochemistry mixed with physicalchemistry which is good.
S5: Yes, it has biochem links to phys. chem concepts.S6: I guess, student who had done biochem had a definite
head start.S8: Yes — chemical kinetics and biological reactions.
3.8 Did the laboratory notes, demonstrators’ guidanceand any other resources help you in learning fromthis experiment? If so, how?
S1: Gives an adequate guide as to where to start.S2: No. Not enough information was given on K. The
notes showed what to expect, but not how to get thereor how to interpret results.
S3: Yes.S4: Yes, the laboratory notes were very helpful.S5: Yes, although demonstrators explanation was
important for my understanding.S6: Yes. they were my only reference. Very good notes.S7: Yes.S8: Yes.
3.9 Are there any other features of this experimentthat made it a particularly good or bad learningexperience for you?
S1: No.S2: Relatively simple experiment but the theory behind
it not well understood.S3: The manual should more clearly explain how Abs is
related to Rate. It was unclear how to interpret resultsto start off.
S4: The results did not work which was a bit of adrawback.
S5: I found the procedure for calculations a littleconfusing. I wasn’t sure what to do with results. ie:Abs a c
S6: The calculations, write-up, and plotting of graphstakes way too long.
S7: None.S8: To much theory on enzyme kinetics to learn that I
didn’t know of.
3.10 What improvements could be made to thisexperiment?
S3: A little more about KI could be included in the theory
section.S4: The actual experiment could be enhanced to facilitate
good results.
S5: More detail related to calculations in method orintroduction.
3.11 Other Comments
No comments were received from students for this question.
References
1. Borchardt, J. K. Chemistry in Australia, 2001, 68 (2), (March), 8.2. Tinoco, I., Jnr.; Sauer, K.; Wang, J. C.; Puglishi, J. D., Physical
Chemistry: Principles and Applications in Biological Sciences;4th Ed.; Prentice Hall: Upper Saddle River (NJ), 2002.
3. Chang, R., Physical Chemistry for the Chemical and BiologicalSciences; University Science Books: Sausalito (CA), 2000.
4. Mathews, C. K.; van Holde, K. E.; Ahern, K. G., Biochemistry;3rd Ed.; Addison Wesley Longman: San Francisco, 2000.
5. Nelson, D. L.; Cox, M. M., Lehninger: Principles ofBiochemistry; 3rd Ed.; Worths: New York, 2000.
6. Cox, B. G., Modern Liquid Phase Kinetics; Oxford UniversityPress: Oxford, 1994; Vol. 21, Oxford Chemistry Primers.
7. Shaw, W. H. R., J. Chem. Educ. 1957, 34, 22.8. Ault, A., J. Chem. Educ. 1974, 51, 381.9. Dunford, H. B., J. Chem. Educ. 1984, 61, 129.10. Moe, O.; Cornelius, R., J. Chem. Educ. 1988, 65, 137.11. Northdrop, D. B., J. Chem. Educ. 1998, 75, 1153.12. Ochs, R. S., J. Chem. Educ. 2000, 77, 145313. Ochs, R. S., J. Chem. Educ. 2001, 78, 3214. Walker, J. R. L.; Wilson, E. L., J. Sci. Food Agric. 1975, 26, 1825.15. Walker, J. R. L. In Australian Chemistry Resource Book 2000; C.
L. Fogliani, ed. Charles Sturt University: Bathurst (NSW), 2000;Vol. 19; p 70.
16. Dunn, R.; Dunn, K.; Treffinger, D., Bringing Out The GiftednessIn Your Child : Nurturing Every Child’s Unique Strengths,Talents, And Potential; John Wiley and Sons: New York, 1992.
17. Winter, M., ChemNZ 1998, 70, 33.18. Hurlbut, J. A.; Ball, T. N.; Pound, H. C.; Graves, J. L., J. Chem.
Educ. 1973, 50, 149.19. Spyridis, G. T.; Meany, J. E.; Pocker, Y., J. Chem. Educ. 1985, 62,
1124.20. Rowe, H. A.; Brown, M., J. Chem. Educ. 1988, 65, 548.21. Hamilton, T. M.; Dobie-Galuska, A. A.; Wietstock, S. M., J.
Chem. Educ. 1999, 76, 642.22. Cornely, K.; Crespo, E.; Earley, M.; Kloter, R.; Levesque, A.;
Pickering, M., J. Chem. Educ. 1999, 76, 644.23. Johnson, K. A., J. Chem. Educ. 2000, 77, 145124. ACNielsen␣ Research␣ Services, Employer Satisfaction with
Graduate Skills: Research Report; Department of Education,Training and Youth Affairs (Australian CommonwealthGovernment): Canberra, 1998, <http://www.detya.gov.au/archive/highered/eippubs/eip98-8/execsum.htm>.
25. McInnis, C.; Hartley, R.; Anderson, A., What did you do with yourscience degree? A study commissioned by the Australian Councilof Deans of Science; Centre for the Study of Higher Education,University of Melbourne: Melbourne, 2001, <http://www.acds.edu.au/ScienceR.doc>.
26. Australian␣ Bureau␣ of␣ Statistics, Business Use of InformationTechnology; Australian Government Publishing Service:Canberra, 1997.
27. Moore, R., J. Coll. Sci. Teach. 1993, 22, 212.28. The Action Research Planner; 3rd revised Ed.; Kemmis, S.;
McTaggart, R., eds.; Deakin University: Geelong (Vic), 1988.29. Zuber-Skerritt, O., Professional development in higher education:
A theoretical framework for action research; Kogan Page:London, 1992, p xv.
30. Barrie, S. C.; Buntine, M. A.; Jamie, I. M.; Kable, S. H., Aust. J.Educ. Chem. 2001, 57, 6.
17
Aust. J. Ed. Chem., 2002, 59,
One-to-one comparison for the teaching of amount balanceand the dimension of the mole
aTetsuo Morikawa* and bBrian T. Newbold
a Department of Chemistry, Joetsu University of Education, Joetsu 943-8512, Japan, [email protected] Department of Chemistry and Biochemistry, Universite de Moncton, Moncton, N.B., E1A 3E9, Canada
AbstractAn arrangement of elementary entities, hereafter called an entity sheet, makes amount balance clear in both stoichiometryand chemical substance. This sheet shows that the principle of comparing one chemical amount with another is one-to-one correspondence, by which the dimension of ‘amount of substance’, including the mole, is constructed. Using thisapproach, students in learning the mole could overcome the confusion between number counting and one-to-one
correspondence.
One of the difficulties in teaching the mole is a gapbetween the atomic/molecular (microscopic) and thechemical substance (macroscopic) worlds. To bridge thegap, Ainley1 and Nelson2 firstly emphasised that the moleis a physical quantity (not a number counting unit), andsecondly used the method of N-times to introduce themole. A stoichiometric equation
C + O2 → CO
2
is given, in which one carbon atom reacts with one oxygenmolecule, producing one carbon dioxide molecule. Thisis a phenomenon in the atomic/molecular world. “Whatcan happen once, can happen N times,” they said. Then,N atoms of carbon combine with N molecules of oxygen,yielding N molecules of carbon dioxide. This is anoccurrence in the macroscopic world of chemicalsubstance. A proper choice of the number N leads to themole expression of the three chemical substances. Themethod of N-times bridges the two worlds. However, insuch a derivation procedure one cannot determine thedimension (class) of chemical amounts and the mole, andhence chemistry teachers cannot clear students’misunderstanding3 such that the mole is a number countingunit.
One-to-one correspondence
One-to-one correspondence is a commonplace conceptwhich people use in everyday life. Let us imagine thefollowing situation: When a pupil returns home no one isthere, but he/she finds three cups of tea on the kitchentable. The pupil could obviously infer that there were threepersons in the room earlier, because of the correspondencebetween cups and persons. The same conclusion mightbe reached by counting numbers because the number inthe example is very small. It should be noted that the twoconcepts, one-to-one correspondence and numbercounting, are often confused. 4
Now let us image another example, metal nuts and bolts.This example in textbooks has often been treated bynumber counting; however, nobody can apply theoperation of number counting to the atomic/molecular
world in chemical reaction, because the order of thenumbers is extremely large (about 1023 for 12 g of carbon-12). Note that the following discussion makes no use ofnumber counting.
Three bags are given. The first bag, called N hereafter,contains nuts, and the second, B, bolts. The third bag,called NB, is empty. An operation is defined as follows:take a nut out of bag N, and also a bolt out of bag B; thenscrew them together, and place into bag NB. Thisoperation can be written as the symbolic equation
N + B → NBwhich looks like a chemical reaction. One repeats theoperation from morning till night. Suppose that the twobags, N and B, become empty at the same time. Then onecan say that the amounts of items in the three bags are thesame, and can thus write
n(N) = n(B) = n(NB)
where n stands for the amounts. Here one might commentthat in the definition of the operation it is simpler forstudents to use the name of the bags and the symbol ofthe nuts and bolts in different notation. In chemistry,however, the name of a chemical substance (e.g., carbon)often coincides with its elementary entity (e.g., C). Hence,the naming of the nuts and bolts follows the usage ofchemistry.
Balancing chemical amounts in chemistry
One-to-one correspondence in the example of nuts andbolts was performed by hand. On the other hand, in thechemical world, reaction corresponds one elementaryentity to another.
Now reconsider the chemical reaction
C + O2 → CO
2
in the atomic/molecular world. Chemists regard thisequation as representing the stoichiometry among threechemical substances, carbon solid, oxygen gas and carbondioxide gas. The chemical substances can thus be
18
Aust. J. Ed. Chem., 2002, 59,
expanded in row form as
{ C C C . . . C }
{ O2 O
2 O
2 . . . O
2 }
{ CO2 CO
2 CO
2 . . . CO
2 }
Such an arrangement of elementary entities is referred toas a chemical entity sheet or simply an entity sheet.5 Hereone row { . . . } stands for a chemical substance, and eachsymbol in the rows indicates an elementary entity. In everycolumn an elementary entity corresponds to another;hence the amounts of the three substances are the same.The equality can then be written as
n(C) = n(O2) = n(CO
2)
which shows amount balance in stoichiometry. Observethe similarity between producing carbon dioxide gas andpacking nuts and bolts.
In the stoichiometric equation
2H2 + O
2 → 2H
2O
two hydrogen molecules react with one oxygen moleculeto produce two water molecules. Then the entity sheet is
expressed as
{ 2H2 2H
2 . . . 2H
2 }
{ O2 O
2 . . . O
2 }
{ 2H2O 2H
2O . . . 2H
2O}
This one-to-one relationship between elementary entities
in the row sets gives the amount balance
n(2H2) = n(O
2) = n(2H
2O)
Here 2H2, O
2, and 2H
2O are elementary entities.
Further expansion of the row sets leads to the new entitysheet
{ H2 H
2 . . . H
2 | H
2 H
2 . . . H
2 }
{ O2 O
2 . . . O
2 }
{ H2O H
2O . . . H
2O | H
2O H
2O . . . H
2O}
Half the amount of the chemical substances, hydrogengas and liquid water, is equal to the amount of oxygengas. Hence one has the amount balance
n(H2)/2 = n(O
2)/1 = n(H
2O)/2
A more generalised form in stoichiometry is written as
aA + bB → cC + dDHere each letter in the upper case stands for an elementaryentity. The entity sheet suggests the amount balancing
n(aA) = n(bB) = n(cC) = n(dD) = n(A)/a = n(B)/b =n(C)/c = n(D)/d
Let us consider amount balance in a chemical substance,e.g., methanol. In this example, a methanol moleculeincludes, i.e., corresponds to, one methyl group, onehydroxyl group and four hydrogen atoms. One-to-one
correspondence no longer needs the entity sheet formethanol, probably. Thus, one gets
n(CH3OH) = n(CH
3) = n(OH) = n(4H) = (1/4)n(H)
Note that the last equality is derived from one-to-onecomparison between rows{ 4H 4H . . . 4H} and{ H H . .. H}. The amount balance in a chemical substance withan elementary entity B is given, in general form, by
n(B) = x n(xB) = x n(Bx)
where x is a positive integer or a positive fraction.
Introducing of the mole and the dimension
The previous discussion did not refer to the unit of ‘amountof substance’. SI (the International System of Units)defines6 the mole as: the amount of substance of a systemwhich contains as many elementary entities as there areatoms in 0.012 kg of carbon-12. This statement impliesthat the molar mass of carbon-12 is equal to 12 g/mol(exactly); i.e., M(12C) = 12 g/mol (exactly).
Let us add to the entity sheet the row set
{ 12C 12C . . . 12C }
which is an expansion of the chemical substance 12C. Theamount of the row set 12 g of 12C is just the mole. Onefraction of one thousandth of the row, or 12 mg of 12C, isdenoted by mmol; 1000 times as long as the row, or 12 kgof 12C, stands for kmol.
The amount of a given chemical substance, for example,oxygen gas, in the formation of carbon dioxide can nowbe measured by means of the mole. Put the mole (the rowof 12C) on the row of oxygen gas, and perform one-to-onecorrespondence between elementary entities. If the oxygengas is, for example, one half of the mole, one can writethis situation as n(O
2)/mol = 1/2, i.e., n(O
2) = (1/2) mol.
The procedures for the use of the mole and that for theyard stick are the same. The mole and n are physicalquantities.6 However, no one can observe directly such aprocedure of measurement in the chemical world becauseone-to-one correspondence only occurs in the atomic/molecular world.
If n(O2) is equal to n(12C) in the two rows of 12C and O
2,
one-to-one comparison implies that
M(O2)/M(12C) = A
r(O
2)/A
r(12C)
where Ar is the relative atomic/molecular mass
(determined by, e.g., mass spectrometry). The IUPACdefinition7 is given by A
r (12C) = 12 (exactly). Hence one
has
M(O2) = (12 g/mol)A
r (O
2)/12 = A
r (O
2) g/mol
It is clear that the elementary entity O2 in this equation
can, in general, be read as B. One can now measure massfor oxygen gas, for example. Let m(O
2) be such mass.
Then balancing molar mass leads to
m(O2)/n(O
2) = M(O
2) = A
r (O
2) g/mol
which gives n(O2).
19
Aust. J. Ed. Chem., 2002, 59,
It should be noted that apparently different physicalquantities (amounts) in the entity sheet are identified bymeans of one-to-one correspondence. The amount balancein the entity sheet suggests the existence of a dimensionconcerning amounts of substance because a dimension isa set of entries which are regarded as the same under someprinciples.8 The dimension of ‘amount of substance’ isnow expressed as
[amount of substance] = { n(C), n(O2), n(2H
2),
n(CH3OH), n(12C), mol, mmol, (1/2) mol, . . .}
The origin of misunderstanding the mole as a counting unitmay reside in the expression, “. . . as many elementaryentities as . . . ,” in the SI definition. There may be attemptsto define the mole, which have no expression with relationto numbers. One example is as follows: The mole is theamount of substance of an elementary entity that has one-to-one correspondence to an atom in 0.012 kg of carbon-12.
References
1. D. Ainley, Educ. Chem., 1991, 28, 18.2. P. G. Nelson, Educ. Chem., 1991, 28, 103.3. G. Gorin, J. Chem. Educ., 1994, 71, 114.4. E. B. Golos, Patterns in Mathematics. Prindle, Weber & Schmidt,
Boston, 1981, chap. 5, sec. 1.5. T. Morikawa and B. T. Newbold, Khimiya (Bulgarian Journal of
Chemical Education), 1999, 8, 285; T. Morikawa and Y.Nishiyama, Bulletin of the Joetsu University of Education (ISSN0915-8162), 1997, 16, 651.
6. I. Mills, T. Cvitas, K. Homann, N. Kally, and K. Kuchitu.,Quantities, Units and Symbols in Physical Chemistry. IUPAC,Blackwell Scientific Publications, Oxford, 1988; 2nd ed., 1993.
7. IUPAC, Pure & Appl. Chem., 1984, 56, 695.8. E. A. Guggenheim, Phil. Mag., 1942, 33, 479.
Correspondence:
Professor Tetsuo Morikawa, Department of Chemistry,Joetsu University of Education, Joetsu 943-8512, Japan.
Registration Fee:RACI members and affiliated groups - $280Non RACI members: $360Registration includes conference mixers, morning andafternoon teas and one copy of the Conference Proceedings.The Conference Dinner is not included in the registration fee.
ProgramInvited Keynote speakers include:Professor John Dearn - Director, Centre for the Enhancementof Learning, Teaching and Scholarship (CELTS), Universityof Canberra.Professor Bill Denny - Director of the Auckland CancerSociety Research CentreOther speakers or workshop leaders will include ProfessorBob Bucat (Uni of WA), Professor Patrick Garnett (EdithCowan University), Professor David Treagust (Curtin), Dr IanJames (APCELL project), Richard Hartshorn (Uni ofCanterbury, NZ), Dr Janet Scott (Monash)The Conference program will include a special day devotedto tertiary Chemical Education issues with a focus on newdevelopments and what is working well. Input from industryand other potential employers of chemistry graduates will befeatured. Another dedicated day for secondary teachers willhave a “new developments in chemistry” theme (co-sponsoredby the Victorian Chemistry Education Association). Numerousworkshops and the normal opportunities for oral and posterparticipation are included.
AccommodationAmple accommodation is available in the vicinity of theUniversity of Melbourne. University College accommodationfor this conference will be hosted by St. Mary’s College on
RACI Division of Chemical Education National Conference 2002“Rejuvenating the Learning and Teaching of Chemistry”
30 November - 4 December, 2002at The University of Melbourne, Parkville, Vic., Australia
the University campus. - $60 per night, includes breakfast.Assistance with the organisation of other accommodation willalso be provided.Expression of Interest in ParticipationI am interested in receiving further information on the
National Conference of the RACI -Chemical Education Division,
to be held in Melbourne in December, 2002
Name: ................................................................................
Title: ...................................................................................
Address: ............................................................................
Country: ............................................................................
E-mail contact details: .......................................................
I am interested in presenting (please tick):A Poster ( .... ), Oral presentation ( .... ), Workshop ( .... )
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Expressions of interest may also be sent to Dr Tony Patti,c/- School of Chemistry, Monash University, Wellington Rd,Clayton, Victoria, 3800, Australia;
E-mail: [email protected]: +613 9905 1620 • Fax: +613 9905 4597
20
Aust. J. Ed. Chem., 2002, 59,
Contemplating Change: A Journey of Reflection Towards Action
a Warren Beasley and b Ester Ocampo
a Graduate School of Education, The University of Queensland, Brisbane, Australia 4072,[email protected] b␣ Dept. of Chemical Engineering, Nacional Universidad del Litoral, Santa Fe,Argentina
AbstractThis paper reports on the effects of a professional development initiative with twenty university chemistry faculty in theDepartment of Chemical Engineering, Nacional Universidad del Litoral, Santa Fe, Argentina. A workshop over fourweeks was conducted with the purpose of producing a cohort of reflective practioners who were committed to undertakeaction research into their own praxis. A model of human action guided the structure of the workshop that analysed fourcontributing influences known to contribute to the raison d’etre of professional practice. These influences are defined aspublic knowledge, personal practical knowledge, worldview and praxis.
The workshop required participants to develop action research proposals consistent with the four dimensions above.Participants were given the opportunity to discuss a range of innovative practices in chemical education as well developappropriate research methodologies to investigate educational aspects of their classrooms. The ability to plan, act,observe and reflect were the key attributes of the action learning cycle for the participants.
The effects on the participants after four weeks of workshop activity are discussed. The participants were also inter-viewed two years later for evidence of change in classroom practice. Analysis of the findings against the current litera-ture on personal change is also provided.
IntroductionThis paper reports on the challenges faced by a group oftwenty professors of chemistry and chemical engineeringwho volunteered to undertake a professional developmentcourse designed to facilitate the process of change in theirclassroom practices. This course was designed anddelivered to give participants the opportunity to analyzetheir own practice.1 The goal was to produce reflectivepractitioners who would choose to act in a way that wouldproduce different learning environments for theirchemistry classrooms.
Understanding the Actions of ProfessionalsMuch of the professional development of teachers at alllevels of the educational hierarchy has assumed the‘teacher as technician’ model. That model denies manyof the developmental needs of the professional teacher.The adapted perspective for this course substitutes a ‘moralorder’ for the ‘causal-technical order’ within which muchdevelopment is traditionally set. 2
This section outlines an analytical framework for the studyof the interactions between knowledge, values andpractices within the professional development process.The essential features of a model of human action aredisplayed in Figure 1 and place the elements within twobackground contexts: the self in relationship with the socialcontext.
Reflection is at the centre of the model and is the open,active communications channel between the social contextand the inner self. Reflection is an evaluative dialoguethat enriches the self and enhances professional practice.Reflection can act as a forum for the decision making thatresults in considered action in the teaching context.
It is hard work to hold these internal debates. They requiretime and energy just to conduct them. And if we take themseriously, we usually find ourselves being urged to takethe more difficult path, the path of more effort rather thanless.3
Figure 1. The elements of the Butler model of human action
Public knowledge includes all that the teachers interactwith in the form of theories, formal knowledge, policydirectives, research results, hints and folklore, communityand student expectations. Public knowledge is a veryvisible and clamorous component of this model. Itattempts to mould and control the professional practice ofthe teacher.
Professional practice of the teacher is the human actionitself. This occurs in the social context when teachers haveto make decisions and act according to theirresponsibilities. This informed action requires the teacherto understand the salient features of the situation. Themodel assumes that professional practice is more deeplyexpressive of the self than of external public knowledge.
SOCIAL SELF
PUBLICKNOWLEDGE
PERSONALKNOWLEDGE
CONTEXT CONTEXT
PROFESSIONALPRACTICE
WORLDVIEW
REFLECTION
21
Aust. J. Ed. Chem., 2002, 59,
Worldview is the individuals own way of looking at theworld derived from tradition and culture and is thereforehistorical and contextual. World view contain a mixtureof rational and irrational beliefs, some contradictoryassumptions, and a tablet of values and rules that the selfholds as true at this stage of its development. Theworldview provides stability but to be effective must becontinuously revised through careful and detailed self-examination.
Personal practical knowledge is a store of knowledge andunderstanding attained through lived experience and isenriched through wider and more vivid experiences andcan be transformed by paradigm shifts in understanding.This conscious and unconscious personal knowing is the‘tacit knowledge’ that has been shown to exert a powerfulinfluence on performance. The personal practicalknowledge that is required for personal and professionaldevelopment cannot be extended systematically andjustification of one’s personal practical knowledge mustappeal to courts other than the courts of reason or strictrules or method. Rather the justification is historical orcontextual; the knowledge is excellent now for this context,it is designed for the how and the now.
The personal practical knowledge that is gained is abouttrusting the self to perform, to trust what one alreadyknows, to be authentic in all ways, to value and use thatwhich has been derived from action and led to fruitfulaction.
Towards Action:
A Journey of Personal RedefinitionThe design and the presentation of this course werefocussed on attaining an outcome, which brought aboutreflection-to-action in the context of university chemicaleducation. This reflection-to-action would need toovercome the mental obstacles that hinder change andenhanced practice. Many of the real obstacles are self-imposed. Modification of professional practice requiresindividuals to alter deeply rooted, self-defining attitudes,values and beliefs. The personal redefinition that thisinvolves is likely to be slow, stressful and sometimestraumatic.
Two well-known characteristics of human action are: thecertainty of human action is never equal to the immediacyof action; and that human action always gives rise tounintended consequences. Both of these features offeropportunities for teachers to learn from undertakingdeliberate and carefully designed practice. The choice ofwhat to do is the beginning rather than the end of theprocesses of justification and reflection.
This introduction to the model of teacher agency informsthe remainder of the paper on teacher professionaldevelopment.
Action Learning as the General Learning ModelAction learning models are widely recognized as one ofthe most powerful ways of assisting people to learn in theworkplace and to change the culture of the workplace.The complete action-learning model requires severalformal journeys around the action-learning loop withoutside assistance. This action learning training modelhas cycles composed of the four processes:
2. ACTIONTHE PLAN
1. PLANTHE ACTION
3. COLLECT DATAON THE OUTCOMES
4. REFLECT, LEARN& REPLAN TO ACT
Figure 2. The Action Learning Cycle
Action learning is also very powerful in creating a cultureof lifelong learning. The participant in an action-learningproject that is designed to progress several times aroundthe loops is often given strong motivation by the self-reinforcing effect achieved by the definite, visible anddeliberate learning that is achieved. The expected outcometherefore is that the participant continues the actionlearning loops long after the program implementation hasbeen finalized.
Action learning has the following key characteristics:
• it involves learning by doing
• “doing” in this case implies a project
• the project is not artificial but involves an actualdevelopment in the department
• the project is undertaken in a systematic and analyticalway and the evaluation of progress and success isbuilt in to the project work
• all participants undertake a systemic analysis of whatthey need to learn to complete a project, and, laterwhat they have actually learned from completing theproject
• this systematic analysis of learning, conducted inparallel with the projects themselves, is cruciallyundertaken as a group activity, even if projectsthemselves are completed by individuals
The Public Knowledge Dimensionof Chemical EducationA volume of course readings was distributed to participantsa month in advance of the commencement of the course.These articles were representative of current theory andpractice (public knowledge) - about learning, teaching andthe assessment of chemistry. Additional resource materialsrelated to research methods in education, providedbackground knowledge and procedures for the conductof action research.
22
Aust. J. Ed. Chem., 2002, 59,
The background readings, however, provided a broadguide. What participants actually planned to do was justas dependent on the understanding of the practicalcircumstances surrounding their own teachingenvironments and their own creativeness. These practicalaspects helped modify the perspectives represented in theliterature. But given their realities, it was easy for all theparticipants to lose sight of the theory. It was therefore allthe more important to use the original or modifiedtheoretical notions as the basis of reflection and as a sourceof criteria for the evaluation of one’s own practice.
Course Outline: Topics and SequenceWeek 11. Introduction: Making Meaning of Action Research
and Personal Change
2. Problem -Based Learning
3. Chemistry Education: Where to now?
4. Review of Related Literature
Examples of the literature in chemical education (PublicKnowledge) were provided in advance as part of the coursereadings. These can be classified under the followingheadings:
A. Knowing Chemistry
B. Teaching and Learning
C. Teaching and Learning About Chemical Change
D. Teaching and Learning About the Particulate Natureof Matter
E. Teaching and Learning About Stoichiometry
F. Teaching and Learning About Chemical Equilibrium
G. Assessment of Thinking Skills and ConceptualUnderstanding
H. Problem Solving
I. Language and Learning of Chemistry
J. Information Technology
K. Microscale Chemistry
L. Chemistry Curricula for Non-Science Majors
M. Gender Issues in Chemistry Education
Week 25. Defining the Research Problem and Identifying the
Research Questions
6. Developing the Research Methodology
7. Exploring Techniques to Gather the Data
8. Selection of a Sample Population
Weeks 3/49. Developing a Research Proposal
10. Discussion of Proposals
The Design of Adult Learning EnvironmentsLearning settings that encouraged participative, democraticprocesses based upon values of collaboration andinterdependence were adopted. In terms of managing andof learning, empowerment - the sharing of power,
knowledge, information and authority was an essentialcharacteristic of the workshop environment.
The adult learning principles that influenced the conductof the course were:
a. Adults have a need to know why they should learnsomething.
b. Adults have a deep need to be self-directing.
c. Adults have a greater volume and different quality ofexperience than youth.
d. Adults enter into a learning experience with a task-centred or problem-oriented or life-centred orientationto learning.
e. Adults are motivated to learn by both extrinsic andintrinsic motivators.
This journey using action research techniques and personalreflection on one’s praxis allows practitioners to innovatein a way that allows movement
from“knowing that” - the cognitive mastery of thetheoretical basis or rationale of processes
to“knowing how to”, the cognitive mastery of processes
to“being able to” - successful use of processes inpractice.
Reflection-to-ActionData were collected from the participants over the 4 weeksof the course (40 hours of formal class contact time). Thisdata consisted of statements written by each participantduring “free write” opportunities. The guidance given tothe participants was as follows:
“Write about your thinking and your feelings on the issuesraised in the course so far as well as the personalchallenges which may have emerged.”
Participants were asked to submit these “free writes”anonymously in Spanish or English.
Participants’ Reflective Writing: Week 1A sample of these writings is presented below:
“I have a lot of questions and expectations... the problemsraised by the course introduction, I feel I recognize thesein my classes also “
“I am interested in changing my ideas and attitudes aboutteaching”
“My experiences with this type of course are very limited.My colleagues do not normally talk about the problems oflearning and teaching... I need to know other points ofview to have the power to make proposals although theymay not be very practical “
“All of us need to reflect about our classes... I don’tunderstand all that I hear but I will try to make use of thisnew knowledge”“Ideas from other countries are interesting but we need
23
Aust. J. Ed. Chem., 2002, 59,
to self assess our actions”
“We need to look inside ourselves to find the desire toteach differently... the course gives us the legs to allow usto advance”
Participants’ Reflective Writing: Week 4“To look into one’s self is not an easy homeworkassignment because we find things that we do not like andsome things that we do. This course gave us the time topause and reflect. This gives us insights, which permitsus to grow- even a small amount. I have much to learnthrough the investigations within my own knowledge andmy students““I feel that the course has opened new perspectives aboutteaching, learning and assessment in chemistry. Thehomework provides areas for investigation. I am not ableto perform to the desired extent at this time and I willneed help and more experience with education and theimplications for teaching the subject matter in chemistry.Although my aims are very clear I need to do moreinvestigations of the literature. I assume I can make thechanges using the action research plan. My workenvironment is strongly scientific and this plays againstresearch in education. I feel that all the efforts will not bereflected in the learning of chemistry students even thoughmy decisions are well intended. I can’t rely on any otherswith a similar view as they are not interested in morelearning outcomes in chemistry. People are moreinterested in self rather than student learning. The lackof the generalization of educational research findingsworries me”“ It is useful to focus on the situation from the students’perspective. To reflect and act to encourage studentlearning from context to concept will be worthwhile”“The course allowed me to organize my ideas. AlthoughI have applied many of the points in the course I believe Ican now organize my course better. The real learningfrom this course will be demonstrated when I put intopractice a new idea and I evaluate the result”“I feel the uncomfortableness of having to change. Thecourse has had the effect of knowing I have to change. Ineed to complete an implementation and see how it willwork”“I have become aware from the information presented inthe course. I am now informed about different teachingapproaches. I was unaware before”“ I believe what I have learned will be useful. I will try toapply these ideas so I can introduce change, whichfavourably enhances student understanding. I amconscious of the need to bring about change and now Ihave ideas about how to change ““The course impacted positively because it empowers theprofessor to make changes in the teaching and learning.It forces one to think about the design of new techniqueswith the objective of awakening a love of learning ““ I found more clarity in the relationship between the topicsthan before. I only understood it intuitively before. I needto review and reflect about the relationship between the
lab and the lecture classes so that I can communicate betterwith my students
And Two Years Later“I have tried to implement some changes in the field ofInorganic Chemistry, particularly about how studentslearn and what are the systematic mistakes they make. Ialso tried to make the classes more integrated (lecture,lab practices, etc), integration of teacher thinking andstudent thinking, trying to explore more deeply whatstudents really think (or they believe they think). I felttotally free (from an institutional point of view) to do this”I’m currently conducting the research on the impact oftechnologies but not as systematically as I would wish.Some outcomes (preliminary) have been very encouraging.Students have responded well; my communication withthem is satisfactorily improving, but there is much moreto do. I feel very comfortable doing this primarily becausemy students and I need it. My perception is that studentsare moving towards better learning. I think the changes Iam trying to make are possible”“It is difficult to change because there are a lot of studentsand a lot of subjects to teach. The work is veryindividualistic for the teacher and there is no assistanceto resolve the administrative problems”“It has been difficult to change because of the lack ofhumility to recognise what we don’t know as well as thelack of stability (political, institutional goals etc)”My attempt to change has not been easy. There are norules or the rules keep changing. We don’t know wherewe will be working or whom we will be working with nextsemester. We need money to research and to gettechnology”
Making Sense of Attempts at Personal ChangeEducational innovation at any level is always fraught withdifficulty and uncertainty. In this particular instance themonth long workshop to encourage university teachers ofchemistry to reflect-to–act so as to develop an action planwas, for the majority of participants, partially successful.The ability and the commitment to reflect about theirpractice in line with Butler’s model in Figure 1 was alwaysgoing to be the major challenge for such professionaldevelopment. The development of personal action plans,although incomplete in the majority of cases, was one ofthe more favourable outcomes of the workshop.
As stated in the ‘free-writes” selected above the intellectualjourney over the one month of the workshop wascharacterised by personal reflection about their currentpractice. There was evidence of movement from theposition of “knowing that,” the cognitive mastery of thetheoretical basis or rationale of processes to “knowing howto”, the cognitive mastery of processes. However with afew exceptions that is where the action stopped. In a returnvisit to the University two years later, the situation wasone of disappointment on the part of the professionaldevelopment providers and desperation on the part of theuniversity staff. The personal actions of staff, characterisedby being able to use the processes in practice, wasevidenced in only three of the original twenty participants.
24
Aust. J. Ed. Chem., 2002, 59,
A selection of the reasons as to why this took place isprovided above.
The challenges associated with change in educationalenvironments has been researched extensively.4,5,6 Findingsfrom such research place some light on this particular setof events. Two important points seem particularly relevantto the two-year data. The first point is that the managementof change requires the power to do so.7 In all of the negativeexamples quoted above reference was made tocircumstances external to themselves that mitigated againsttheir willingness to act differently. These circumstanceswere to do with departmental administrative constraints;university rules governing student entry standards andnational economic conditions leading to job insecurity.Most of these respondents indicated that to attempt changeduring these uncertain times would place their professionallives at risk. This was understandable given that themajority of the staff attending this workshop was not senioracademics in the department. On the other hand theseconcerns may appear on the surface to be based onirrational beliefs about change and professional risk. Onlyfurther debriefing of the participants’ worldviews wouldreveal the true basis of these stated concerns.
A second point emphasized in research findings is thatresources are the appetites of change.8 In an economicallydeprived department this is indeed a major issue and seemsto be reflected in this particular case with many participantspointing to the lack of technological and administrativesupport. Change does require additional resources for newmaterials and for time. Time is energy and time is money.Good resourcing abjures any false pride about self-sufficiency and it requires nous to go outside the normalframework in reallocating available resources.
In ConclusionThis project was essentially about a professionaldevelopment initiative that would encourage universityteaching staff in chemistry to reflect-to-act. The four-weekworkshop provided the catalyst for this personal reflectionto be undertaken and the evidence was provided in thepersonal action plans of most of the participants. For somethis four-week period proved to be very challenging.Teaching and learning were viewed as non-problematic.
Issues raised during the course to do with student learningof chemistry were seen as issues for students not forteaching staff. Therefore the challenge to reflect-to-actresulting in a personal action research proposal about theirpraxis proved to be insurmountable. However theworkshop did result in the production of action researchplans and as such provided the platform for the next step– to investigate some aspects of their personal praxis.The failure of most of the participants to continue withtheir action research proposals over the following twoyears proved to be disappointing. This failure to“institutionalise” the planned changes in personal practiceis consistent with earlier research findings that suggestthat change is a journey not a blue print and that change isloaded with uncertainty. Rational planning models ofsocial change do not work; rather it is a guided journeywhere strategy is viewed as a flexible tool, rather than asemi-permanent expansion of their mission. Anxiety anddifficulties are intrinsic to all successful change asinnovation represents new personal meaning and newlearning.The following comment is an appropriate epitaph for thisproject which commenced with good intentions andcommitment by the staff but for many, economiccircumstances unimaginable in most western countriesbecame overwhelming for the whole society at large. “ I can’t change very much because of the economicinstability of the country, the strong structure of theuniversity, poor integration of the areas in the departmentand the shallow background of the students allows anarrow range of new actions in the time we have withthem”
References1. Butler, J. Educ. For Teaching, 1992, 18(3), 221-238.2. ibid.3. Peck, M. The Road Less Travelled, 1987, 272.4. Fullan, M. G. Change Forces: Probing the Depths of Educational
Reform, London: The Palmer Press, 1999.5. Hargreaves, A.; Evans, R, Eds. In Beyond Educational Reform:
Bringing Teachers Back In, London: Open University Press, 1997.6. Fullan, M. G.; Miles, M. B. Phi Delta Kappan, 1992, 745-752.7. Fullan, M. G. Successful School Improvement, Buckingham, UK:
Open University Press, 1992.
8. ibid.
25
Aust. J. Ed. Chem., 2002, 59,
Visualisation and Mental Manipulation of Molecular StructuresJanette Head and Robert Bucat
Chemistry, School of Biomedical and Chemical Sciences, The University of Western Australia,
AbstractAn investigation of three-dimensional visualisation abilities of tertiary chemistry students and faculty has been conductedusing interviews. Participants were asked to decide whether two representations of a stereocentred molecule are identicalor enantiomers. It was found that (i) there are considerable differences between the abilities of students to do thesetasks, and (ii) each student and faculty member consistently employs an idiosyncratic strategy. There is a wide varietyof such strategies, some of which are quite surprising. Explanations that teachers use may be inconsistent with theidiosyncratic approaches of their students.
IntroductionUnderstanding the three-dimensional arrangement ofatoms in molecules is fundamental to learning chemistry.So it is of some concern that anecdotal evidence fromchemistry lecturers at the tertiary level suggests that manystudents experience difficulty when interpreting two-dimensional representations of the three-dimensionalstructures of molecules.
It is common for lecturers to use blackboard or OHPdrawings to teach about stereochemistry, perhaps assumingthat the students visualise the representations in the sameway the lecturer does. Organic chemistry textbooks containmany drawings, such as skeletal structures, space-fillingmodels and Newman projections, and students need to beable to construct and mentally manipulate three-dimensional images from these drawings to understandthe text (Pribyl & Bodner, 1987). While there has beenmuch interest in the relationship between generic spatialability and achievement in chemistry courses (for example,Carter, LaRussa & Bodner, 1987; Coleman & Gotch, 1998;Friedel, Gabel & Samuel, 1990), very little is known aboutthe abilities of tertiary chemistry students to visualise thespatial arrangements of atoms in molecules.
Tuckey, Selvaratnam and Bradley (1991) used “elementaryitems”, which test for just one visualisation skill, todiagnose the origins of student difficulties when visualisingthree-dimensional structures. Prior studies had not beenable to identify the sources of students’ difficulties, becausethe researchers tested for overall competence in three-dimensional thinking tasks. Tuckey et al. report that themajority of students had difficulty in making use of thedepth cues on a representation of a three-dimensionalstructure, and in visualising the position of the atoms afterrotation or reflection. These workers used genericrepresentations of molecules, with substituents A, B, Cand D, rather than specific substances.
This StudyThe research reported here comprised part of a widerinvestigation of stereochemical visualisation abilities ofundergraduate chemistry students, which includedassessment of skills such as• the ability to imagine the three-dimensional structure
depicted by a representation• the ability to imagine the structure represented by a
diagram from a different perspective and to draw adiagram ‘seen’ from that new direction
• the ability to mentally rotate a structure representedby a diagram and to depict the result with a drawing
• the ability to decide whether drawings of twostereocentred molecules of the same substance areidentical or non-superimposable mirror imageenantiomers.
The focus is on the variety of approaches that can be usedto undertake a particular stereochemistry task that requiresvisualisation of the three-dimensional structures ofmolecules represented by diagrams and mentalmanipulation of the imagined structures.
The tasks involve simple stereocentred molecules in whichthe central carbon atom is bonded to four differentsubstituent groups. In particular, the tasks require thestudent to compare two representations of stereocentredmolecules, each with the same four substituent groups, todecide whether they are identical or enantiomers. This isnot immediately obvious, as illustrated in Figure␣ 1.
CHO
C
HOCH2OH
H
OH
C
OHCH
CH2OH
CH2OH
C
HOH
CHO
H
C
HOH2CCHO
OH
R-glyceraldehyde R-glyceraldehyde
S-glyceraldehyde S-glyceraldehyde
Figure 1. Recognition that the two molecules of R-glyceraldehydeare identical, that the two molecules of S-glyceraldehyde areidentical, and that the two R-glyceraldehyde molecules are mirrorimages of the two S-glyceraldehyde molecules is not possiblewithout mental manipulation of the three-dimensional structuresimagined from the representations, or the use of short-cutstrategies.
26
Aust. J. Ed. Chem., 2002, 59,
Figure 2. An example of problems used to evaluate studentvisualisation abilities.
This van’t Hoff style of representation was deliberatelychosen to direct the students’ attention to the tetrahedralarrangement of the substituent groups around thestereocentre. Other ways of representing the structure ofalanine, such as Fischer or Newman projections, wereregarded as inappropriate because some of the participantslacked familiarity with the conventions of their use. Theuse of this style of representation also avoids any difficultythat may originate from students’ inability to identify thestereogenic carbon atom in other types of representation.
During interviews, students and lecturers did not haveaccess to molecular models. We have found that whenpeople are given molecular models, the task is usuallysolved quickly - presumably because it does not involvevisualisation of the structure represented by a diagram,and particularly because it does not involve mentalmanipulations of the visualised structure. Our concern iswith situations, such as those that most commonly existduring lectures, where students do not usually havemodels, and mental manipulation of imaginary three-dimensional structures is necessary for sense-making.
While a number of studies have documented genderdifferences in the abilities of students to visualise andmentally rotate imagined structures (Bodner & Guay,1997; Halpern, 1986; Voyer, Voyer & Bryden, 1995), itwas not an aim of this study to distinguish the students’abilities according to gender.
ResultsOur findings indicate there a variety of strategies thatstudents use to approach a task such as that in Figure 2.This is illustrated below by reference to selected studentswho exemplify the various strategies. Pseudonyms areused.
Amy was a first-year student who consistently did the typeof task shown in Figure 2 by mentally manipulating herimagined structure of A to compare it with her mentalimage of structure B. She always manipulated structure Aso that it had the same substituent at the top as structureB: that is, she rotated A so that it had the C-CH3 bond inthe same place as it appears in B. Amy was then able todetermine whether A was the same as B or different fromB by comparing the arrangements of the other threesubstituents. Amy comments on her problem-solving
method:
I like to have the same one at the top, then it’s easierfor me to turn it around at the bottom. /... / You have tohave the top ones the same or nothing looks the same.To me, anyway.
Andrew, a first-year student, used a method that involvedsomewhat complicated logic. He drew the mirror imageof structure A and then mentally manipulated B to see ifwas superimposable upon the mirror image of A. If it was,then he concluded that A and B were enantiomers. If Bwas not superimposable upon the mirror image of A, heconcluded that B and the mirror image of A had a mirror-image relationship and so B and A were identical. Heconsistently used this strategy in a number of tasks.
Another first-year student, Allan, always used a particularstrategy which compensated for his relatively poor abilityto mentally manipulate three-dimensional structures. Allanwould imagine looking along the H-C bond in eachstructure, and draw a two-dimensional representation ofthe three substituents that he would ‘see’. He comparedthe arrangement of the three groups in each structure bychecking whether a chosen sequence was clockwise oranti-clockwise. Allan explained his approach in thefollowing way:
I can’t visualise it as to turning and stuff like that. /.../ I find it easiest just to look down one of the bonds tosee whether the other three [substituents] are in thesame order.
Derek was a final-year student who, like Andrew, first drewthe mirror image of structure A. He would then mentallymanipulate structure B to see whether it is identical to Aor to the mirror image of A. If B and A were found to beidentical, the problem was resolved. If B and the mirrorimage of A were identical, he would conclude that A andB were mirror images. Derek described how he completedthe task as follows:
... you’ve asked me if it’s going to be a mirror image,so, of course, I’m going to do a reflection at some stage./... / ... firstly do the reflection of one of them. /... / Theaim then is to arrange for at least two of the groupsattached to the other carbon [in structure B] to beorientated in the same way as two of the groups here[on the mirror image]. /... / ... with the carboxylic groupand the hydrogen in the same orientation as in themirror image of the first molecule /... / it becomesobvious to me that the amine group and the methylgroup are orientated differently.
Darryl’s way of thinking about tetrahedral structures was toimagine them balancing on a single group with three groupscoming up out of the plane of the paper. Darryl (a final-yearstudent) manipulated both of the structures into an orientationfrom which he could compare them. Here he describes howhe used his strategy to determine the relationship betweenthe alanine structures shown in Figure 2:
D: ... draw them so that they look the same (re-drawingboth structures). So basically you’ve got a tripod, withfeet sticking in the air and bouncing on the hydrogen
During individual and small-group interviews, students andlecturers were given tasks such as that shown in Figure 2.
Alanine: Are these mirror images or superimposable?
CO2H
C
H2NCH3
H
CH3
C
HCO2H
NH2
A B
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Aust. J. Ed. Chem., 2002, 59,
group. /... / So then they’re the same molecule.
I: ... any particular reason why you have the hydrogengoing into the page, and not something else?
D: ... it’s arbitrary, the way I do it, you can put anythinginto the page, as long as it’s consistent.
Final-year student Cary, who showed highly-developedvisualisation skills, employed a method that was differentfrom those of all other students. He was able to do thetask mentally without drawing intermediate structures. Hementally rotated structure A around an axis that bisectsboth the CH
3-C-H angle and the CO
2H-C-NH
2 angle. From
the researchers’ experiences during the study, includinginterviews with lecturers, this seems to be a ratherextraordinary ability. What Cary achieves by complexmental manipulations may require other students withlesser visualisation ability to do a number of rotations,drawing each of the intermediate structures as theyproceed. Cary described his strategy in the interview:
... match this first one to this second molecule by havingthe methyl group vertical and the hydrogen /... / just tosee if it is a mirror image, then finding it’s not, rotatingthe molecule around 180 degrees, the ‘oxylate’ [CO
2H]
and the amine [NH2] are going to match up to the first
one. Therefore it’s superimposable.
In contrast to Cary’s exceptional ability to visualise andmentally manipulate an imagined structure is that ofDonna, a highly successful honours student in organicchemistry. During the interview, Donna described herselfas having
... a lot of trouble doing three-dimensional visualisation,and I remember, in my exams, with pens and things,trying to do them. / ... / I know some people can justlook at something and rotate it in their mind, but I justremember having different coloured pencils withdifferent coloured matchsticks on the end, and I sit therein exams, going, trying to see what’s going on. I justcan’t do it in my head.
Donna tried to use an approach similar to Allan’s, as shedescribes:
I just kept redrawing the molecule, so that, lookingalong this bond each time, the amine to carbon bond,trying to get a different perspective of the moleculeand comparing it to the other one that was supposedto be the mirror image or not the mirror image, orwhatever.
Donna experienced considerable difficulty. Her lack ofvisualisation skills made the task very frustrating, as isevidenced here:
... Because I couldn’t just sort of look at it and rotateit mentally. So I tried to redraw it, hoping it wouldeventually look like a mirror image or it would becomedefinitely apparent that it was or wasn’t, but it sort ofnever got to that point. / ... / I can’t just pick it up andturn it around in my mind. / ... / I can never get it to thepoint where I can swap that, the carboxylic acid group,with anything. That’s always at the top and I don’t
know how to ... That’s really dumb, I should knowhow to do this. It’s annoying. / ... / I just can’t work outhow to do it, how to redraw it, it’s annoying me.
All of the lecturers interviewed during the study wereexperienced instructors whose teaching schedules rangedfrom first-year introductory chemistry for non-chemistrymajors to third-year bio-inorganic and polymer chemistrycourses. All of them acknowledged that there are manydifferent ways of solving the problems, but each lecturerhad a preferred method. Some lecturers preferred to usemethods that are unlike any used by students and theseare reported here.
Errol used shortcuts he had developed with his experiencesin molecular symmetry to help him compare one of thestructures with the other. He swapped the CH
3 and CO
2H
groups on structure A, so they were in the same positionsin both structures. Swapping the positions of two groupsin a structure has the same effect as making the mirrorimage of the structure. Errol noted that the arrangementof substituents after the groups were swapped was differentto structure B, so he concluded that the two alaninemolecules must be the same.
Eric rotated structure B around the C-H bond and thencompared the resulting structure with structure A. Withall of the tasks Eric completed, he rotated around ormatched that bond in the plane of the paper (C-H instructure B). He describes his strategy of using the bondin the plane of the paper as a “fixation”.
Edward also had a fixed way of solving all of the first-year level problems he was shown. His method involvedthe use of the Cahn-Ingold-Prelog rules to assign the R orS configuration of each molecule. When he was asked totry to tackle the problems by mental manipulation of thestructures (as a first year student might be expected todo), Edward usually tried to put the hydrogen atom behindthe plane of the page as required by the Cahn-Ingold-Prelogrules, and then compared the order of the other threesubstituents. Using the C-H bond as his focus made itdifficult for Edward when the structure was in anorientation that he did not find easy to manipulate so thatthe C-H bond was behind the plane of the page:
This hydrogen up in the air is a much harder exercise,I think. /... / I always find it easier to have the hydrogen,your group four, as a ‘foot’ rather than as an ‘up in theair’.
Emmett consistently used a strategy similar to that of Allan,in that he reduced a three-dimensional task to a two-dimensional task:
I’ll view it opposite the CH2OH because it’s behind
the plane of the paper, and I’ll go from hydrogen tocarboxyl to amino. Go in an anticlockwise direction,yeah. Now if I view this from underneath, then hydrogenand carboxyl and NH
2 are also going to be in an
anticlockwise direction. / … / They’re bothanticlockwise. So they’re superimposable. / … / So Iguess what I do each time is I visualise down a bond.
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Aust. J. Ed. Chem., 2002, 59,
Unlike Allan, Emmett did not need to draw the two-dimensional arrangements of substituents.
DiscussionTwo issues emerged from the interviews: the ease (ordifficulty) with which interviewees completed the tasks,and the strategies that they used to go about the tasks.
While no formal test was administered to interviewparticipants, it was observed that there were markeddifferences between the three-dimensional visualisationabilities of students. In contrast to reported evidence thatsuccess in chemistry is linked to spatial ability, thevisualisation abilities of highly successful advancedstudents Cary and Donna appeared to be at opposite endsof the spectrum. It seems that Donna had learned strategiesto cope with her lack of visualisation skills.
Before interviewing the lecturers, it had been supposedthat most lecturers would have developed a commonpreferred way of tackling simple stereochemistryproblems. The findings concerning the variety of methodsused by lecturers, along with the variety of methods usedby the students, confirms that most people have a particularpreferred way of “seeing” stereochemical relationships.
The different approaches used by students and lecturersto complete a task like that shown in Figure 2 can beclassified as follows:
1. One structure is compared with the other by mentalmanipulation of the corresponding three-dimensionalimages (e.g., Amy, Cary, Errol, Eric).
2. The structures are compared with each other aftermental manipulation of both corresponding three-dimensional images (e.g., Allan, Darryl, Edward).
3. The mirror image of one structure (X) is created andthis is compared with the other structure (Y) bymental manipulation of their three-dimensionalimages. Once the relationship between Y and themirror image of X has been ascertained, logicaldeduction is used to determine the relationshipbetween the structures X and Y (e.g., Andrew).
4. The mirror image of one structure (X) is created andthen the three-dimensional image of the otherstructure (Y) is mentally manipulated to see whetherit is the superimposable upon X or upon the mirrorimage of X (e.g., Derek).
Within each of these broad approaches, there areidiosyncratic differences of strategies. For example,strategies such as matching the top substituent of bothstructures, completing the problem by complex mentalmanipulations of imagined structures, swapping pairs ofsubstituents on structures, and matching the structure sothere are common bonds in the plane of the paper were allused by people classified as having a Type 1 approach.
We observed a number of students and lecturers, such asAllan and Emmett, who reduced the three-dimensionalvisualisation aspect of tasks to a two-dimensional issue.Either by mentally shifting their point of view, or by
rotating and redrawing the structure, they would considerthe arrangement of just three substituent groups aroundthe stereocentre.
There have been many suggestions (Bishop, 1978; Burnett& Lane, 1980; Lord 1985, 1987) of teaching strategies toimprove general visualisation skills, but specific strategiesto assist chemistry students’ visualisation of molecularstructures are harder to find. Perhaps it might be importantfor students to practise not only translating diagrams intothree-dimensional structures (as is often done) but also topractise drawing diagrams of molecular models (as isseldom, if ever, done). Rehearsing the transition betweenthree-dimensional figures and two-dimensionalrepresentations may improve the students’ abilities to ‘see’the three-dimensional image in their mind without the aidof a molecular model.
It might be expected that students’ abilities to solveproblems such as those shown in Figure 2 would beenhanced by allowing students to use molecular modelsto do stereochemistry practice problems during tutorial orlaboratory sessions. Combined with continued rehearsalof the transition between three-dimensional figures andtwo-dimensional representations, the students will be ableto develop their own visualisation and mental manipulationskills. Rather than simply watching a lecturer use amolecular model or computer image to illustrate a pointduring class, students handling molecular models whiledoing problems can make their own choices about solvingstrategy and learn visualisation skills at their own pace.
SummaryThe following findings, related to mental manipulation ofstructures of simple molecules with one stereogenic centre,have implications for chemistry lecturers and textbookwriters:• Students majoring in organic chemistry differ widely
in their abilities (including both correctness andrapidity) to mentally manipulate and comparestructural representations.
• Even academic staff in organic chemistry maydisplay and acknowledge difficulty in mentalmanipulation of structural representations, andfrequently use techniques that reduce a three-dimensional visual problem to a two-dimensionaltask. This suggests that three-dimensionalvisualisation is an inherent ability which is not easilyamenable to improvement.
• Students use a wide range of strategies to comparedifferent structures. Each student uses a consistentstrategy from task to task. Any explanation used ina lecture situation will be at odds with the way thatat least some students prefer to compare structuralrepresentations.
• Some students have preferences for the orientationof representation certain molecules, particularly inrelation to the positioning of a hydrogen atom or alarge substituent group.
Of course, the eventual objective is to improve the
29
Aust. J. Ed. Chem., 2002, 59,
functional ability of students, but the case has been madethat we should not presume too much of the visualisationabilities of students, nor of the strategies that students useto go about comparison of structures. For example, whilelecturer Edward finds it easier to have the hydrogen, yourgroup four, as a ‘foot’ rather than as an ‘up in the air’, hemay consistently use this orientation without being awarethat students have their own different preferences. Thesame applies when a lecturer tries to demonstrate theenantiomeric relationship between two structures usinghis or her preferred approach.
Presumably with representations that do not have thestereogenic centre explicitly indicated, with more complexmolecules such as those encountered in biologicalsituations, and with molecules that have more than onestereogenic centre, the student difficulties might beexacerbated.
ReferencesBishop, J. E. (1978) Developing students’ spatial ability. The ScienceTeacher, Nov, 20-23.
Bodner, G. M., & Guay, R. B. (1997). The Purdue visualisation ofrotations test. The Chemical Educator, 2, 1-18.
Burnett, S. A. & Lane, D. M. (1980). Effects of academic instruction onspatial visualization. Intelligence, 4, 233-242.
Carter, C. S., LaRussa, M. A., & Bodner, G. M. (1987). A study of twomeasures of spatial ability as predictors of success in different levels ofgeneral chemistry. Journal of Research in Science Teaching, 24, 645-657.
Coleman, S. L., & Gotch, A. J. (1998). Spatial perception skills ofchemistry students. Journal of Chemical Education, 75, 206-209.
Friedel, A. W., Gabel, D. L., & Samuel, J. (1990). Using analogs forchemistry problem solving: Does it increase understanding? SchoolScience and Mathematics, 90, 674-682.
Halpern, D. F. (1986). Sex differences in cognitive abilities. Hillsdale,NJ: Lawrence Erlbaum Associates.
Lord, T. R. (1985). Enhancing the visuo-spatial aptitude of students.Journal of Research in Science Teaching, 22, 395-405.
Lord, T. R. (1987). Spatial teaching. The Science Teacher, Feb, 32-34.
Pribyl, J. R., & Bodner, G. M. (1987). Spatial ability and its role inorganic chemistry: A study of four organic courses. Journal of Researchin Science Teaching, 24, 229-240.
Tuckey, H., Selvaratnam, M., & Bradley, J. (1991). Identification andrectification of student difficulties concerning three-dimensionalstructures, rotation and reflection. Journal of Chemical Education, 68,460-464.
Voyer, D., Voyer, S., & Bryden, M. P. (1995). Magnitude of sexdifferences in spatial abilities: A meta-analysis and consideration ofcritical variables. Psychological Bulletin, 117, 250-270.
Book Review Carbohydrates: The Sweet Molecules of Life
Robert V. StickAcademic Press, 2001, 256 pp, ISBN 0-12-670960-2.
Despite the rather alluring title,this book is overwhelminglyconcerned with the syntheticmanipulations of carbohydrates.Stick makes this clear in hisPreface. As such, however, thebook provides an excellenttreatment of the subject, with briefbut informative coverage of themore biological aspects of moderncarbohydrate science.
The work begins with a thoroughtreatment of the history ofcarbohydrate science, with EmilFischer being a central characterin this discussion. Entwined inthis history are explanations ofmany of the commonly used toolsand terms used in carbohydratechemistry, including Fischer andHaworth projections, the furanoseand pyranose terminology,mutarotation, the conformationaldescriptors of the cyclic forms ofsugars and the anomeric effect.
The central chapters, being thebulk of the book, deal withsynthetic aspects of carbohydratechemistry. Useful background on
many standard organictransformations, includingoxidations, reductions,halogenations and the Wittig andMitsunobu reactions is provided. Ahandy coverage of the use ofprotective groups also appears inthis part. The formation ofglycosidic linkages is canvassed ingreat detail, and excellentexplanations of modern conceptsused in carbohydrate synthesis suchas “armed” and “disarmed”,“torsional control”, and “latent” and“active” are given and aresubsequently used to explainsynthetic results. Synthesis onpolymers supports, combinatorialsynthesis and synthesis withenzymes also get a mention.
The final chapters deal with themore biological aspects ofcarbohydrate science. While notclaiming to be all-encompassing,these chapters provide a usefuloverview of modern developmentsin the area.
Throughout the book, Stick makescopious reference to the literature,
including review articles, andclearly, as much as possible, triesto “give credit where credit isdue”. He writes in a familiar,informal style which, combinedwith a liberal sprinkling of wittyquips and quotes, makes“Carbohydrates: The SweetMolecules of Life” a highlyreadable and entertaining referencebook. Students studyingcarbohydrate chemistry at thirdyear and honours level, or thoseresearching carbohydratechemistry, will find this book veryuseful. It is an ideal text forhonours courses on carbohydratechemistry. Instructors teachingcarbohydrate chemistry from firstyear University upwards will findthis text ideal for placing thematerial they are teaching into abroader context, as it delves deeperinto carbohydrate chemistry thanthe standard organic texts we usetoday.
Peter J. DugganSchool of ChemistryMonash University
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Aust. J. Ed. Chem., 2002, 59,
The word on chemistryAllan Mitchell
Chemistry, University of New England, Armidale NSW 2351, [email protected]
Had I been born a few thousand years ago in ancient Egypt,I would have had reason to pay homage to an assortmentof deities depending upon what my particular problem wasat the time. The top spot in the theological pecking orderwas held by Amen, also written as Ammon. Variousinterlopers came along and installed their own deities, ormerged with existing ones, resulting in e.g. an EgyptianAmmon-Ra, a Greek Ammon-Zeus and Roman Ammon-Jupiter. Whereas Ammon is said to mean the “HiddenOne”, Sanskrit-speaking Indus Valley dwellers spoke of a“Sky Father” or Dyaus Pitr which others subsequentlyaltered to Zeus Pitr, Zeu pitr, Jupiter or just plain Zeus.So, he was important.
A Roman temple raised to Ammon-Jupiter was apparentlythe site of a bit of old-world chemical tinkering with somelocal shrubbery and animal dung. One product, despiteits derivation from animal dung, was thought of so muchthat it was sanctified with the name of the Salt of Ammon,i.e. sal ammoniac, now ammonium chloride.
Jumping Jupiter you might say – well, don’t. The overallmeaning of dyaus extended from sky to that of day andgave us diurnal, altered in French to talk of a day bookcalled a journal (and a diary), despite J. Aust. Ed. Chem.emerging somewhat less frequently.
We now know that ammonia is a compound of hydrogenand nitrogen, with oxygen thrown in when in theammonium form. When first described, these were utteredin French as hydrogene, nitrogene and oxygene, the -genesuffix relating to generate, each describing some attributeof a product. Hydrogen was water-forming, with hydradenoting water; oxygen was acid-forming, Greek oxysdescribing a sharpness of taste; and nitrogen was nitron-forming apparently due to the resemblance of its salts tothe Greek nitron or Egyptian ntry, a native hydratedsodium carbonate.
Now, water is a very common substance and the Romansseemed to have had a variety of names depending on whatit was doing at the time. The term water convolutinglycomes from an undulating Roman wave or unda, butwithout reference to its location. For sea water, Romanstook their word for salt, being sal and relating to the Greekhals, and came up with salo. Being paid in salt resultedin salaries while hals gave rise to halides or fish-breath.A piece of land in the sea had begun as a terra in salo,reducing to simply insalo, something definitely insularand isolated. The hydra, one might recall, was a many-headed water snake, or hydrus, killed by Hercules. ThisRoman-Greek s-h relationship is also seen in solar and
helium, from sol and helios for the sun, and, funnilyenough, in silly and hilarious.
There was a time when silver was thought to take on a lifeof its own and flow like water. Though we now refer tothe material as mercury, this watery silver or hygragyrum,hence Hg, was commonly called quicksilver, not becauseit was fast but because it was lively. Quick has thefundamental meaning of being alive and relates to vitaland vivacious from the Latin vivas, whose earlier formwas qvivas. The winged messenger Mercury was a fellowknown to be rather lively, having wings on his feet andbeing the god of travel, eloquence, cunning, theft andcommerce, apparently handy attributes for merchants inthe marketplace, then and now.
I’m not sure if Mercury every got to Argentina but, if hehad, his talents would have served him well. Named forargentum, this land simply oozed with silver (Ag), thoughit didn’t actually flow like water. The Greeks knew themetal as argyros, simply meaning white or bright, alsoseen in the white stone they called lithargyros, nowlitharge, or lead oxide, all stemming back to rajata,Sanskrit for white and shiny. Should the preceding notionslead to an argument, it would be quite appropriate as arguecomes from arguere, to make clear, and links with theillumination associated with argentum, as opposed tosquabbling.
If one can’t have silver, be happy with gold. The Romangold was aurum, hence Au, the colour of dawn (usas inSanskrit), controlled by the goddess Ausosa (later alteredto Aurora) who associates with Eostre every Easter atthe dawn of the new year (in the Northern Hemisphere).Gold itself links with chlorine and cholera by being geolu,i.e. yellow (often greenish), also giving us gall, glass andyolk.
It is often said one should end with a good joke, but I’llsettle for being a bit jovial, or the original jovialis, i.e.pertaining to Jove, a grammatical from of Jupiter fromdyaus via divam. This requires that one’s birth occurredunder the ascendency of Jupiter, fating one to be joyousand jolly, such being the astrological call signs of tin. Tothe Romans, this was stannum, hence Sn, thought to linkto the Celtic tain. Stannum has also been stagnum, alsoprepared by alchemists as an amalgam of silver and lead,and describing a pool of water with no outlet, leading tostagnation and stink, while tain was a native tin bashedflat and polished as a mirror. In reflection, then, one mightnow be tempted to say that Jupiter has been reduced to thelevel of a little tin god?
31
Aust. J. Ed. Chem., 2002, 59,
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Aust. J. Ed. Chem., 2002, 59,
Contents Page
In the laboratory* Laser-based liquid prism sucrosemeter: An APCELL experiment. 5
Vicky Barnett
* Inhibition of the reaction kinetics of the enzyme o-diphenol oxidase: 11An APCELL experiment.Kieran F. Lim
Discussion paper* One-to-one comparison for the teaching of amount balance and the dimension of the mole 17
Tetsuo Morikawa and Brian T. Newbold
Research papers* Contemplating change: a journey of reflection towards action 20
Warren Beasley and Ester Ocampo
* Visualisation and mental manipulation of molecular structures 25Janette Head and Robert Bucat
Book reviewCarbohyadrates: The Sweet Molecules of Life - R. V. Stick 29Peter J. Duggan
The word on chemistry. 30Allan Mitchell
* Refereed papers