教案成果讲稿

UNIVERSITYOFCAMBRIDGEINTERNATIONALEXAMINATIONS

GeneralCertificateofEducation

AdvancedSubsidiaryLevelandAdvancedLevel

CHEMISTRY 9701/32

AdvancedPracticalSkills2 May/June2012

INSTRUCTIONS

Greatcareshouldbetakentoensurethatanyconfidentialinformationgivendoesnotreachthecandidateseitherdirectlyorindirectly.

TheSupervisor’sattentionisdrawntotheformonpage7whi ustbecompletedandreturnedwiththescripts.

IfyouhaveanyproblemsorqueriesregardingtheseInstructions,pleasecontactCIEby :

international@.uk,

byphone: 4,

byfax 8,

statingtheCentrenumber,thenatureofthequeryandthesyllabusnumberquotedabove.

This consistsof8printedpages.

IB1206_9701_32CI/3RP

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Safety

Supervisorsareadvisedtoremindcandidatesthatallsubstancesintheexaminationshouldbetreatedwithcaution.

Onlythosetestsdescribedinthequestionpapershouldbeattempted.Pleasealsoseeunder‘Apparatus’ontheuseofpipettefillers,safetygogglesandsticgloves.

InaccordancewithCOSHH(ControlofSubstancesHazardoustoHealth)Regulations,operativeintheUK,ahazardappraisaloftheexaminationhasbeencarriedout.

Attentionisdrawninparticular,tocertainmaterialsusedintheexamination.Thefollowingcodesareusedwhererelevant.

C corrosivesubstance F highlyflblesubstance

H harmfulorirritatingsubstance O oxidisingsubstance

T toxicsubstance N dangerousfortheenvironmentTheattentionofSupervisorsisdrawntoanylocalregulationsrelatingtosafetyandfirst-aid.

‘HazardDataSheets’,relatingtomaterialsusedinthiamination,shouldbeavailablefromyourchemicalr.

BeforetheExamination

AccesstothequestionpaperisNOTpermittedinadvanceoftheexamination.

Preparationofmaterials

Wheretiesarespecifiedforeachcandidate,theyaresufficientfortheexperimentsdescribedinthequestionpapertobecompleted.

Inpreparingmaterials,thebulktyforeachsubstanceshouldbeincreasedby25%assparematerialshouldbeavailabletocoveraccidentalloss.Morematerialmaybedifrequestedbycandidates,withoutpenalty.

Allsolutionsshouldbebulkedandmixedthoroughlybeforeusetoensureuniformity.

Everyeffortshouldbemadetokeeptheconcentrationsaccuratetowithinonepartintwohundredofthosespecified.

Supervisorsareaskedtocarryoutanyconfirmatorytestsgivenonpage4toensurethematerialsdareappropriate.

Iftheconcentrationsdifferslightlyfromthosespecified,theExaminerswillmakethenecessaryallowance.Theyshouldbeinformedoftheexactconcentrations.

Labellingofmaterials

Materialsmustbelabelledasspecifiedintheseinstructions.MaterialswithanFBcodenumbershouldbesolabelledwithouttheidentitiesbeingincludedonthelabel.WhereappropriatetheidentityofanFBcodedchemicalisgiveninthequestionpaperitself.

Identityofmaterials

ItshouldbenotedthatdescriptionsofsolutionsgiveninthequestionpapermaynotcorrespondexactlywiththespecificationsintheseInstructions.Thecandidatesmustassumethedescriptionsgiveninthequestionpaper.

Sizeofgroup

Inviewofthedifficultyofthepreparationoflargetiesofsolutionofuniformconcentration,itis mendedthattheumnumberofcandidatespergroupbe30andthatseparatesofsolutionsbepreparedforeachgroup.

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Apparatus

Inadditiontothefittingsordinarilycontainedinachemicallaboratory,theapparatusandmaterialsspecifiedbelowwillbenecessary.

Pipettefillers(orequivalentsafetydevices),safetygogglesanddisposableglovesshouldbeusedwherenecessary.

Foreachcandidate

125cm3measuringcylinder

2100cm3beaker

250cm3burette(oneoftheseshouldbelabelledFB1)2standandburetteclamp

2funnelforfillingburette

3teat/droppipette

1stopclockorsightofaclockwithsecondsdisy

1whitetile

2boilingtubes*8test-tubes*

1test-tuberack

1test-tubeholder1glassrod

1Bunsenburner1heatproofmat

1washbottleofdistilledwaterpapertowels

*Candidatesareexpectedtorinseandre-usetest-tubesandboilingtubeswherepossible.Additionaltubesshouldbeavailable.

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ChemicalsRequired

Itisespeciallyimportantthatgreatcareistakenthattheconfidentialinformationgivenbelowdoesnotreachthecandidateseitherdirectlyorindirectly.

Particularrequirements

hazard

label

percandidate

identity

notes

(hazardsgiveninthiscolumnarefortherawmaterials)

FB1

120cm3

0.050moldm–3acidifiediron(III)chloride

Dissolve13.52gofFeCl3.6H2O[H]ineachdm3of0.2moldm–3hydrochloricacid.

FB2

75cm3

0.050moldm–3potassiumiodide

Dissolve8.30gofKIineachdm3ofsolution.

FB3

150cm3

0.005moldm–3sodiumthiosulfate

Dissolve24.82gofNa2S2O3.5H2Oineachdm3ofsolutiontomakeastockof0.1moldm–3.Dilutethissolution20-fold.

FB4

75cm3

starchindicator

Seepreparationinstructionsonpage68ofthe2012syllabus.

[H]

FB5

15cm3

1.0moldm–3sulfuricacid

Seepreparationinstructionsonpage67ofthe2012syllabus.

[T][N]

FB6

15cm3

0.1moldm–3potassiumchromate(VI)

Dissolve19.42gofK2CrO4[T][N]ineachdm3ofsolution.

[H]

FB7

15cm3

0.2moldm–3bariumchlorideand

0.5moldm–3sodiumchloride

Dissolve48.8gofBaCl2.2H2O[T]and29.25gofNaClineachdm3ofsolution.

[T][N]

FB8

15cm3

0.2moldm–3leadnitrate

Dissolve66.2gofPb(NO3)2[T][O][N]ineachdm3ofsolution.

[H]

FB9

15cm3

1.0moldm–3sodiumnitrite

Dissolve69.0gofNaNO2[T][O][N]ineachdm3ofsolution.

distilledwater

80cm3

distilledwater

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Thereagentsbelowshouldalsobeavailable.Ifnecessary,theymaybemadeavailablefromacommunalsupply:however,theattentionoftheInvigilatorsshouldbedrawntothefactthatsuchanarrangementmayleadtocontaminationofreagentsandenhancetheopportunityformalpracticebetweencandidates.

hazard

label

notes

[H]

dilutehydrochloricacid

Seeidentitydetailsandpreparationinstructionsonpage67and68ofthe2012syllabus

[C]

dilutenitricacid

[H]

dilutesulfuricacid

[H]

aqueousammonia

[C]

aqueoussodiumhydroxide

[H]

[H]

0.1moldm–3bariumchlorideor

0.1moldm–3bariumnitrate

[H][N]

0.05moldm–3silvernitrate

[T][N]

0.1moldm–3lead(II)nitrate

[H]

limewater

[T][N]

acidifiedaqueouspotassiumdichromate(VI)

Thefollowingmaterialsandapparatusshouldbeavailable.

rinedandbluelitmuspapers,

filterpaperstripsforusewithdichromate(VI),aluminiumfoilfortestingnitrate/nitrite,woodensplintsandthe

apparatusnormallyusedintheCentreforusewithlimewaterintestingforcarbondioxide.

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ResponsibilitiesoftheSupervisorduringtheExamination

TheSupervisor,orothercompetentchemist,must,outofsightofthecandidates,carryouttheexperimentsinQuestion1andcompletetablesofreadingsonasparecopyofthequestionpaperwhichshouldbelabelled‘Supervisor’sResults’.

Thisshouldbedonefor:

eachsessionheldandeachlaboratoryusedinthatsession,andeachsetofsolutionsd.

N.B.Thequestionpapercoverrequeststhecandidatetofillindetailsoftheexaminationsessionandthelaboratoryusedfortheexamination.

ItisessentialthateachpacketofscriptscontainsacopyoftheapplicableSupervisor’sResultsasthecandidates’workcannotbeassessedaccuraywithoutsuchinformation.

TheSupervisormustcompletetheReportFormonpage7toshowwhichcandidatesattendedeachsession.Ifallcandidatestooktheexaminationinonesession,pleaseindicatethisontheReportForm.AcopyoftheReportFormmust panyeachcopyoftheSupervisor’sResultsinorderforthecandidates’worktobeassessedaccuray.

TheSupervisormustgivedetailsonpage8ofanyparticulardifficultie periencedbyacandidate,especiallyiftheExaminerwouldbeunabletodiscoverthisfromthewrittenanswers.

AftertheExamination

EachenvelopereturnedtoCambridgemustcontainthefollowingitems.

Thescriptsofthosecandidatesspecifiedonthebarcodelabelprovided.

AcopyoftheSupervisor’sReportrelevanttothecandidatesin1.

AcopyoftheReportForm,includingdetailsofanydifficultieperiencedbycandidates(seepages7and8).

TheAttendanceRegister.

ASeatingnforeachsession/laboratory.

Failuretoprovideappropriateationineachenvelopemaycausecandidatestobepenalised.

COLOUR-BLINDNESS

Withregardtocolour-blindness–aminorhandicap,relativelycommoninmales–itispermissibletoadvisecandidateswhorequestassistanceoncoloursof,forexampleprecipitatesandsolutions(especiallytitrationend-points).Pleaseincludewiththescriptsanoteofthecandidatenumbersofsuchcandidates.

Experiencesuggeststhatcandidateswhoarered/greencolour-blind–themostcommonform–donotgenerallyhavesignificantdifficulty.Reportingsuchcaseswiththescriptsremovestheneedfora‘SpecialConsideration’applicationforthishandicap.

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REPORTFORM

ThisformmustbecompletedandsenttotheExaminerintheenvelopewiththescripts.

CentreNumberNameofCentre

Supervisor’sResults

PleasesubmitdetailsofthereadingsobtainedinQuestion1onasparecopyofthequestionpaperclearlymarked‘Supervisor’sResults’andshowingtheCentrenumberandappropriatesession/laboratorynumber.

Thecandidatenumbersofcandidatesattendingeachsessionwere:

FirstSession SecondSession

TheSupervisorisrequiredtogivedetailsoverleafofanydifficultie periencedbyparticularcandidates,givingnamesandcandidatenumbers.Theseshouldincludereferenceto:

anygeneraldifficultiesencounteredinmakingpreparation;

difficultiesduetofaultyapparatusormaterials;

accidentstoapparatusormaterials;

assistancewit