resource pack teacher's guide - vula : gateway : welcome · worksheets and quizzes are not...

resource pack

teacher's guide

Petrochemicals Chlor-alkali Batteries Fertilisers

CHEMICAL INDUSTRIES RESOURCE PACK CreativeCommonsBY-NC-SA

CONTENTS

Introduction 2

Overview 3

Work schedule 5

Animations worksheetsFertilisers 7

Batteries 12

Chlor-alkali 16

Petrochemicals 19

Animation memosFertilisersmemo 21

Batteriesmemo 25

Chlor-alkalimemo 28

Petrochemicalsmemo 31

Research assignment 33

Practical worksheetsCellchargeanddischarge 39

Rateofelectrolysis 43

Propertiesoffloorwax 47

Practical memosCellchargeanddischargememo 51

Rateofelectrolysismemo 54

Propertiesoffloorwaxmemo 57

Glossary 60

Copyright information 63

Disclaimer 63

The people behind this resource pack 64

The sponsors 64

Contact information 64


INTRODUCTION

DearScience-teachingcolleague

This resource pack was prepared by the Schools Project Team of the Department of ChemicalEngineeringat theUniversityofCapeTown.TheSchoolsProjectwas initiatedafter the introductionof theFET school syllabus in 2006.The first resourcepackonMiningandMineralProcessingwascompleted in2009.This resourcepack is thesecond in theseries.Wehavebeen fortunate tohavehadthefinancialsupportoftheCentreforExcellenceinCatalysis(c*change),SasolLtdandPetroSAforthisresourcepack.

Althoughwehavetriedtomakethisresourcepacksuchthatavarietyofschoolsfromdifferentcontextswouldfindituseful,werealisethatnooneresourcewillbeaone-size-fits-all.Thisisthereforenottheultimateresource,buthopefullyapackthatwillsupportteachersintheteachingofChemicalSystemsinameaningfulway.

Thisresourcepackconsistsofateacher'sguide,learnerinformationsheets,asetofposters,aperiodictable,animationsandmoviesofpracticalwork.Intheteacher'sguideyouwillfindthreemainsections:animations,researchassignmentandpractical investigations.Onthefirstfewpagesoftheteacher'sguideyouwill findsomesuggestionsonhowtousethispack in integrating itscontent intoteachingChemicalChangeandChemicalSystems.

This teacher'sguide iswrittenundera copyright restriction thatallowsyou tomakechanges to thecontent and print copies of it for non-commercial use in your school. Please refer to the copyrightinformationonpage63ofthisguide.PleasenotethattheinformationincludedinthelearnerinformationsheetsaswellasthemoviesandanimationsontheaccompanyingDVDcanbereproduced,butmaynotbechangedinanyway.

We would appreciate your feedback concerning this resource pack. Please send us an email([email protected])orfaxyourcommentsto0216505501.

UCTChemicalEngineeringSchoolsProjectTeam

10September2010

INSTRUCTIONSFORDVD

Included in thisresourcepackyouwill findaDVD. Insert theDVDinto theD-driveofyourcomputerandopen itusing the 'MyComputer' icon.Tostart theDVD,clickon the 'start-here' icon.Click 'Yes'if an Active content warning appears. This programme will not harm your computer. If you do nothaveamovieplayerorPDFreaderinstalledonyourcomputer,pleaseopenthe'Installers'folderandinstallAdobeAcrobatPDF reader,QuicktimePlayer (for themovies) orAdobeFlashPlayer (for theanimations).


OVERVIEW

PurposeThis resource pack provides you with teaching and learning material to supplement your teachingofGrade 12ChemicalSystems.Simultaneously, itwill support you in your teaching of someof thesectionsofChemicalChange,asfollows:

Topic (Chemical Systems) Associated section(s) in Chemical Change

Fertilisers Equilibrium

Batteries Electrochemistry:voltaicandelectrolyticcells

Chlor-alkali Electrochemistry:electrolyticcells

Petro-chemicals Organicchemistry

Resource summaryThe following table summarises the resources provided and a general sequence to follow in usingthemincontentteachingandlearning.Refertotheglossaryofterms(pp.60-62),andmakeuseofthepostersandperiodictableincludedinthepack.Alsonotetheresearchassignment:pp.33-38.

Topic Resources Action Reference

TG page Other

Learnersheets Teach,aidedbyrelevantlearnersheets.Seeteachingschedule. 5

Learnersheets

AnimationsWorksheetMemo

Watchanimations.

Completeworksheet.

Discuss.Correctwithmemo.

Disc

7

21

Quizzes Answerelectronicquizzes. Disc


Learnersheets


Watchanimations.

Completeworksheet.


Disc

12

25

PracticalmoviesWorksheetMemo

Watchpracticalmovies.

Completeworksheet.


Disc

39

51



Learnersheets


Watchanimations.

Completeworksheet.


Disc

16

28

PracticalmovieWorksheetMemo

Watchpracticalmovie.

Performpractical.Completeworksheet.


Disc

43

54



Learnersheets


Watchanimations.

Completeworksheet.


Disc

19

31

PracticalmovieWorksheetMemo

Watchpracticalmovie.

Completeworksheet.


Disc

47

57


Fe

rtil

ise

rsB

att

eri

es

Ch

lor-

alk

ali

Pe

tro

ch

em

ica

ls


RationaleThefollowingtablesummarisestheintendedpurposeofeachofthetypesofresources.Notethattheworksheetsandquizzesarenotmeant tosimulateexam-stylequestions.Theyareahelpfulstartingpointtohelplearnersgraspthebasiccontent.

Resource Purpose Style Motivation for style

Animations Toaidteachingandlearningofcontent.

Visualandaudiofeaturesareprovided.

Learners'attentionisdirectedtorelevantaspectsinaclearandincrementalway.

Animation worksheets

Tofocuslearners'attentionwhiletheywatchtheanimations.Toserveasnotesforlaterreference.

Shortanswers,columns,True/False,gap-filltexts.

Quicktocompleteafterwatchingtheanimations.Quicktomarkwhilere-watchingtheanimations.Engagelearnerswiththeanimationcontent.Serveasnotesforlaterreference.

Electronic quizzes Toaidlearningofcontent.

Shortanswers,columns,True/False,gap-filltexts.

Quicktocomplete.Interactive.Giveimmediatefeedback.

Practical movies: Cell charge & discharge,Properties of floor wax

Toguidelearnersthroughthebasiccomponentsofanexperimentalinvestigation.

Investigationsaredemonstratedbytheteacher.Learnersarenotnecessarilyexpectedtoperformtheseinvestigations.

Generalcomponentsofanexperimentalinvestigationarefocussedonwithoutthecognitiveloadofactualexperimentation.Thisprepareslearnersfortheelectrolysispractical.

Practical movie: Electrolysis

Toguidelearnerstoplan,perform,analyseandreportonanexperimentalinvestigation,whichthelearnersperformpracticallythemselves.

Eachstepintheprocessisdiscussed,followedbyanexpectationforlearnerstorespondbeforeproceeding.Learnersshouldpreferablyperformthisinvestigationpractically.

Learnersneedtoapplytheirknowledgeofexperimentalinvestigationstoundergotheentireinvestigationprocess.Thisinvolvesplanning,performing,analysingandreportingonfindingsforaninvestigation.

Practical worksheets Tosupportthepracticalmoviesinachievingtheirpurposes.

Shorttomediumlengthanswers,tableandgraphcompletion.

Easytocompleteatrelevantpauseswhilewatchingthemovieorperformingtheinvestigation.

Posters Tosupportteaching. Clear.Attractive. Suitableasteachingaids.

Periodic table Areferencesource. Includesmoreinformationthanmostperiodictables.

Providesadditionaldatafortheteachertouseinteaching,andforlearnerstoreferto.

Learner sheets Tosupportteaching.Resourcesforaresearchproject.

Graphicandattractive,withalargeamountofinformation.

Suitableasateachingaid.Usedinresearchproject,learnerswillhavetoextractrelevantinformation.

Research assignment

Toguidetheprocessofextracting,analysingandsynthesisinginformation.

Overarchingcontroversialquestions.Guidingcontentquestions.Rubricandnotesondoingaresearchassignment.

Havingtoansweracontroversialquestiondiscouragescopying-and-pasting,andencouragescriticalthinking.Guidanceenableslearnerstomanagethetask.

SequenceThe various industries can be taught in any sequence. However, we recommend that batteries betaughtbeforeeitherchlor-alkaliorpetrochemicalssincethebatterypractical(p.39)hasbeendesignedtoeaselearnersintothescientificmethod.Thepetrochemicalpractical(p.47)repeatsthisprocess,inamoredifficultcontext,andthechlor-alkalipractical(p.43)requireslearnerstoapplytheirlearningtotheirownplanningandperformanceofanexperiment.Itmakessensetoteachbatteriesandchlor-alkaliconsecutively, as they both involve electrochemistry, thereforewe suggest the sequence: fertilisers,batteries,chlor-alkali,petrochemicals.


WORKSCHEDULE

General approachThis table summarises the two approaches you could take in organising the teaching of ChemicalChangeandChemicalSystems:

Approach Explanation Advantage

Integrated Teachbothsectionssimultaneously,usingtheChemicalSystemsapplicationstoillustratewhatyouteachinChemicalChange.

Moretimeefficient.

Sequential TeachChemicalChangefirst,followedbyChemicalSystems.

RevisitingChemicalChangetopicsafteradelaycanbeeffectiverevision.

Forsimplicity,theworkschedulegivenbelowrefersonlytotheteachingofChemicalSystems.Ifyoufollowanintegratedapproach,youwillneedtoinserttherelevantsectionsfromChemicalChange,andincreasethetimeallocatedtoeachtopic.

NotationF1.2isanexampleofthenotationusedtorefertothelearnersheets.ThisreferstoFertiliser learnersheetnumber1,page2.Eachindustryisabbreviatedusingitsfirstletter.

Schedule

Topic Suggested time

Notes Link to resources

Relevant learner sheet numbers

Other

Fertilisers (5 lessons)

Introduction 1lesson DefinitionanduseNPKratios

NPKratio:F1.2Organic&inorganic:F9.1

Haber, Ostwald, Contact Processes

2lessons Applicationof:dynamicequilibriumLeChatelier'sprinciple

PropertiesH2&N2:F4.1Haber,NH3properties:F4.2OstwaldProcess:F5.1ContactProcess:F5.2Flowchart:elementstofertiliser:F7.2Ammonia,limestone,nitricacidflowcharts:F11.2

Animationsandanimationworksheet

Electronicquizzes

Formation of fertiliser salts

1lesson Acid-basereactionsWritingformulaeBalancingequations

Lime:F3.2(bottomleft)Phosphate:F6.2,F11.1

Environmental impact

1lesson Eutrophication Sustainabledevelopment:F9.2Eutrophication:F12.1

Batteries (6 lessons)

Voltaic cell 2lessons UseofredoxpotentialtableRedoxreactions

Basics,redox,conduction,electrolyte,cellstructure:B1

CellchargeanddischargemovieandworksheetElectronicquizzes

Types of batteries

1lesson Primaryandsecondary:linktovoltaicandelectrolyticcellsLearnersfindhalfreactionsforeach,writebalancedreactionandcalculatecellpotentials

Firstcells.Leclanchcell:B2Primary,secondary:B3.1Zinc-carbon,alkalinecells:B6Mercurycells:B5.1Nickelcells:B7.1Lithium-ioncells:B8.1

Batterydismantlingmovie


Lead acid battery 2lessons Charging:electrolyticcellDischarging:voltaiccell

Leadacidbatteries:B4.1 AnimationsandanimationworksheetElectronicquizzes

Environmental issues

lesson RecyclingFuelcells

Recycling:B9;Flowchart:B9.1FuelCell:B11Lifespandetails:B12

Calculations lesson CellcapacityEnergystored

Amp-hour:B3.2

Chlor-alkali (4 lessons)

Electrolysis 2lessons RedoxreactionsElectrolyticcells

Electrolyticcells:C1Applications:B1

ElectrolysismovieandworksheetElectronicquizzes

Types of cells in chlor-alkali industry

1lesson Membrane,diaphragm,mercurycells

Diaphragmcell:C8Membranecell:C9Mercurycell:C10

AnimationsandanimationworksheetElectronicquizzes

Applications of the chlor-alkali industry

lesson Salt:Revisebonding

Saltdefinition:C2Crystallattice:C2

lesson NaOHandsoap:EsterreactionPolarityanditsrelevancetosolubility

Sodiumhydroxide:C6.1Soapformation:C6.2Likedissolveslike:C7.1Soapfilm:C7.2

lesson Chlorine:UseandionformationApplications

Uses:C3.1Reactions:C3.2Electrolysisinpools:C3.2HOCl-,HCl:C4.1PVC,polymers:C4.2

Petrochemicals (3 lessons)

Introduction 1lesson Alkanes,alkenes,polymers:structuresanduses

Molecularrepresentations:P1.2Alkanes:properties:P1.1Organicsolvents:P12.1

Propertiesoffloorpolishmovieandworksheet

Fischer-Tropsch reaction

1lesson EnergychangesinreactionsRolesofcatalysts

Fischer-Tropschtechnology:P8,P9

Animationsandanimationworksheet

ElectronicquizzesFractional distillation

lesson Separatingcrudeoil/Fischer-Tropschproductsintoitscomponents

Fractionaldistillationofoil:P3.1,P1.1

Cracking lesson Organicchemistryofcracking

Cracking:P3.2

Environmental issues

lesson Combustionoforganiccompounds

Combustionoforganics:P6.1Naturalgaspros&cons:P7.2


FERTILISERS

Overview 1Whyisnitrogenimportanttoplants?

2Inwhatformscanplantsabsorbnitrogen?

3Completetosummarisetheindustrialprocesses:

Process Reactants Products of step 1 Products of step 2 Final products

Haber notapplicable

Ostwald

Contact

Haber Process4WhatisthepurposeoftheHaberProcess? Toproduce from and .

5WriteabalancedequationfortheHaberProcess'sreversiblereaction:

+ 6Namesomeusesofammonia.

7Nametwoconditionswhichmustbemetforareactiontoreachequilibrium.

8Nametwocharacteristicsofequilibrium.

9IntheHaberProcessanironoxidecatalystisusuallyused.Rutheniumcanalsobeused.Whatdoesacatalystdoinareaction,andhowdoesitdothis?


10Circlethecorrectoption(True/False)foreachofthefollowing:i AcatalystspeedsuptheHaberProcess'sforwardreactionmorethanthereverse.[True/False]

ii Acatalystwillcausemoreproducttobeformed. [True/False] iii A catalyst will decrease the time it takes to reach equilibrium because it speeds up both forwardandreversereactions. [True/False]

iv Acatalystspeedsbothforwardandreversereactionsequally. [True/False]

11LinkeachelementfromColumnAwithitscorrespondingelementinColumnB. WritetheletterfromAnexttoeachiteminBinthelastcolumn.

Column A Column B A

adynamicequilibrium absorbsheat

bendothermic ameasureoftheaveragekineticenergyofparticles

cexothermic disturbsequilibrium,favoursincreasedcrowding:moremolecules

dLeChatelier'sprinciple 273Kand101,3kPa

edecreaseinpressure disturbsequilibrium,favoursexothermicreaction

fincreaseinpressure releasesheat

gremovingheat astateinwhichforwardandreversereactionsoccuratequalrates

haddingheat forceperarea,ingasesrelatedtorateofparticlecollisions

itemperature disturbsequilibrium,favoursdecreasedcrowding,fewermolecules

jpressure disturbsequilibrium,favoursendothermicreaction

kSTP whenasystemwhichisinequilibriumisdisturbed,itwillrespondinsuchawayastocounteractthedisturbance

Le Chatelier: Effect of pressure12Completetheexplanationbyfillingthegapsorchoosingfrom theoptions.Dothisbefore,orafter,butnotduring,watchingthe animations.Markduringre-watching.

Increased pressureAccording to principle, when a system

whichisinequilibriumisdisturbed,itwillrespondinsuchawayas

to the disturbance. An increase in pressure

[de/in]creases the crowding of gaseousmolecules. The systemwill respond by [de/in]creasing their

crowding. Crowding is decreased in gases when [fewer/more] molecules are formed. In the Haber

Process the [forward/reverse] reactionmakes fewermolecules than the [forward/reverse] reaction. In

the forward reaction molecules of ammonia aremade from every molecules of

reactants( N2and H2molecules).Consequently,anincreaseinpressure

equilibrium forawhilebymaking the [forward/reverse] reactionoccurat

ahigherratethanthe[forward/reverse]reaction.Thiscauses[more/less]ammoniatobeformedand

[more/less]nitrogenandhydrogen.Afterawhileanewdynamicequilibrium is reached.Theratesof

forwardandreversereactionsareagain tooneanother,and theamountsof reactants

andproductswill [change/remainconstant].However,compared tobefore thepressurewasapplied,

there will now be [more/less] ammonia present at equilibrium. The equilibrium constant value, Kc,

however,willbe[higherthan/lowerthan/thesameas]itwasintheoriginalequilibrium.


Decreased pressureDecreasing pressure [de/in]creases the crowding of gaseous

molecules.Thesystemwillrespondby[de/in]creasingtheircrowding.

Crowding can be increased by forming [fewer/more] molecules. In

theHaberProcess,thatmeansthatforawhilethe[forward/reverse]

reactionwilloccuratahigherratethanthe[forward/reverse]reaction.

Thereversereactionchangesevery moleculesofammonia

into molecules( nitrogenand hydrogen

molecules).Thiscausestheamountofammoniapresentto[de/in]creaseandtheamountofnitrogen

andhydrogento[de/in]crease.Whilethisishappeningthesystem[is/isnot]inequilibrium.Afterawhile

anewdynamicequilibriumwillbereached,inwhichtheratesofbothforwardandreversereactionswill

oneanother,andtheamountsofreactantsandproductswillremain .However,

compared to before thepressurewasdecreased, therewill nowbe [more/less] ammoniapresent at

equilibrium.Theequilibriumconstantvalue,Kc,however,willbe[higherthan/lowerthan/thesameas]

itwasintheoriginalequilibrium.

Optimum pressureIn the Haber Process, we want to make as much as

possible. We want the dynamic equilibrium to be such that a lot

of [reactant/product] is formed. A(n) [de/in]crease in pressure will

cause more products to form. We need as [low/high] a pressure

as it is safe and economical to use. We say we need to use an

pressure: the pressure forwhichwe get a good

yieldforareasonablepricewhilestillbeingsafe.Pressuresbetween

200and300atmospheresaretypicallyusedintheHaberProcess.

Le Chatelier: Effect of temperature13Completetheexplanationbyfillingthegapsor choosingfromtheoptions.Dothisbefore,orafter,but notduring,watchingtheanimations. Markduringre-watching.

HeatingHeating a reaction up increases the energy of the

particles,andsocausesthemtoreactmore[slowly/rapidly]withone

another.Additionally,heatcanhaveaneffectondisturbingthe ofareaction.

In theHaberProcesstheforwardreaction is [exo/endo]thermicandthereverse is [exo/endo]thermic.

Thismeansthatasnitrogenandhydrogenreactwithoneanothertoformammonia,heatis[absorbed/

released],butasammoniabreaksupintohydrogenandnitrogen,heatis[absorbed/released].According

toLeChatelier'sprinciple,whenasystemwhichis inequilibriumisdisturbed, itwillrespondinsuch

awayas to counteract thedisturbance.So if heat is added to a system in theHaberProcess, the

[exo/endo]thermic [forward/reverse] reaction is favoured to [absorb/release]someof thatheatandso

[cool thesystembackdown/heat thesystembackup].Boththeforwardandreversereactionsoccur

at[lower/higher]ratesthanbeforetheheatwasadded,duetotheadditionalkineticenergyofall the

particles, but the [forward/reverse] reactionwill have been speeded up to a greater extent than the

[forward/reverse]reaction.Soforawhile,thesystemwillnotbein


as the [forward/reverse] reaction occurs more rapidly than the [forward/reverse] reaction.

This will [in/de]crease the amount of ammonia present, and [in/de]crease the amount of hydrogen

andnitrogen.Afterawhileanewdynamicequilibrium is reached.The ratesof forwardand reverse

reactions are again to one another, and the amounts of reactants and products will

remain .However,comparedtobeforetheheatwasadded,therewillnowbe[less/

more] ammonia present at equilibrium. A new equilibrium constant, Kc, [higher than/lower than/the

sameas]thatoftheoriginalequilibrium,isreached.

CoolingCoolingasystemthatisinequilibriumhastwoeffects.Firstly,by[de/in]creasingthekineticenergyof

allthemolecules,it[reduces/increases]theratesofboththeforwardandreversereactions.Secondly,

ithas theeffectofdisturbing the by favouring the [exo/endo]thermic reaction

untilanewequilibriumisreachedwith[thesame/adifferent]equilibriumconstant.

IfheatisremovedfromasystemintheHaberProcess,the[exo/endo]thermic[forward/reverse]reaction

isfavouredto[coolthesystembackdown/heatthesystembackup].Forawhile,thesystemwillnot

be in as the [forward/reverse] reaction occurs more rapidly than the [forward/

reverse]reaction.Thiswill[in/de]creasetheamountofammoniapresent,and[in/de]creasetheamount

ofhydrogenandnitrogen.Afterawhileanewdynamicequilibrium is reached.The ratesof forward

andreversereactionsareagain tooneanother,andtheamountsofreactants

andproductswillremain .However,comparedtobeforethesystemwascooled,

therewillnowbe[less/more]ammoniapresentatequilibrium.Anewequilibriumconstant,Kc,[higher

than/lowerthan/thesameas]thatoftheoriginalequilibrium,isreached.

Optimum temperatureIntheHaberProcess,wewanttogetahighammoniayield.We

want a dynamic equilibrium which makes as much ammonia

product as possible. Consequently, we need to use a fairly

[high/low] temperature. However, this causes a problem,

namely

.

Therefore, a compromise is made, and a temperature of

approximately450Cisoftenused.

Units of pressure and temperature

14Completeforunitsofpressure.

Unit Pressure at sea level at 0CName Symbol


15KelvinistheSI(StandardInternational)unitfortemperature.Completeforconversions.

Temperature in degrees Celsius (C) Temperature in Kelvin (K)

0

0

100

200

25

Ostwald Process16WhatisthepurposeoftheOstwaldProcess? Toproduce from .17HowistheproductoftheOstwaldProcessusefulforthe fertiliserindustry?

18Whydoesn'titmatterthattheplatinumcatalystusedisveryexpensive?

19Complete.

Step 1 Step 2 Step 3

Contact Process20WhatisthepurposeoftheContactProcess? Toproduce from .21Namesomeusesofsulfuricacid.

22Complete.

Step 1 Step 2 Step 3 Step 4

+

+

catalyst

+

catalyst

+

+

+

+


BATTERIES

Types of cells1Complete/choosefromtheoptionstosummarisethetypesofcells.

Primary Secondary

Rechargeable? [rechargeable/non-rechargeable] [rechargeable/non-rechargeable]

Voltaic/Electrolytic? [onlyvoltaic/voltaicandelectrolytic] [onlyvoltaic/voltaicandelectrolytic]

Namesomeexamples

Voltaic cells2Onthefollowingdiagram:

aAddtheselabels:electrolyte,saltbridge,+electrode,-electrode bComplete/choosefromtheoptionstosummarisethecompositionofavoltaiccell.

3Answerconcerningthesaltbridge:aWhatisitspurpose?

bWhatkindofsubstancemustitbemadeof?

cWhymustitbemadeofthistypeofsubstance?

4Choosefromtheoptionsforavoltaic cell.

VOLTAIC CELL

Anode Cathode

[oxidation/reduction] [oxidation/reduction]

[positive/negative] [positive/negative]

[Battery/Voltmeter]

ANODE:

[oxidation/reduction]

CATHODE:


VoltaicCell

Converts energy energyasa[spontaneous/non-spontaneous]chemicalreaction

createsa acrosstwoelectrodes.


5Circlethecorrectoption(True/False)foreachofthefollowingreferringtoavoltaic cell.

VOLTAIC CELL: aAbatterymakesoneelectrodepositiveandtheothernegative,andthiscausesachemical reactiontooccur. [True/False]

b A chemical reaction occurs, and this causes one electrode to be made positive and theothernegative. [True/False]c As oxidation happens, chemicals lose electrons, which then go onto the anode, makingitnegative. [True/False]d The anode is made to be negative, and this makes chemicals lose electrons there,causingoxidationtohappen. [True/False]eAs reduction happens, chemicals accept electrons, taking them from the cathode, causing ittobecomepositive. [True/False]f The cathode is made to be positive, and this makes chemicals gain electrons there,causingoxidationtohappen. [True/False]

Lead acid battery (Car battery)

Overview6Aleadacidbatteryconsistsof[primary/secondary]cells.7Complete/choosefromtheoptions.

Discharging Charging

[electrolytic/voltaic]cells [electrolytic/voltaic]cells

[produces/requires]electricalenergy [produces/requires]electricalenergy

Chemical reaction

[spontaneous/non-spontaneous] [spontaneous/non-spontaneous]

[exothermic/endothermic] [exothermic/endothermic]

Energy con-version

energyenergy

energyenergy

Anode [Pb/PbO2] [Pb/PbO2]

Oxidation reaction

Cathode [Pb/PbO2] [Pb/PbO2]

Reduction reaction

Net redox reaction

Discharging8Completetheexplanationbyfillingthegapsorchoosingfromtheoptions.Dothisbefore,orafter,butnotduring,watchingtheanimations.Markduringre-watching.

OverviewWhen the lead acid battery is discharging it behaves as a set

of [electrolytic/voltaic] cells. Each lead acid battery consists of

six cells. Only one of these is shown here. Each cell converts

energy into energy,

asa[spontaneous/non-spontaneous]chemicalreaction[requires/

creates]apotentialdifferenceacrosstwoelectrodes.Aleadacid

battery has one electrodemade of lead dioxide and another of

lead.Theseareinsidea acidelectrolyte.


AnodeLead atoms in the lead electrode are [oxidised/reduced]: they [gain/lose] two electrons each. This

changes them into [positively/negatively/neutrally] charged lead [atoms/ions] of formula .

Since [oxidation/reduction] occurs at this electrode,we call it the anode. ThePb2+ ionsmove away

fromtheelectrode, leaving theelectrons theyhad just lostbehindontheelectrode.Thismakesthis

electrode, theanode, [positively/negatively/neutrally]charged,creatinga

between it and the other electrode, which is positive relative to it. This causes electricity to flow

betweenthetwoelectrodes.

CathodeElectrons move from the [lead/lead dioxide] anode to the [lead/lead dioxide] cathode. There the

electrons are [accepted/released] by positively charged ions in the

leaddioxideelectrode.The lead ionsherehavea [4+/2+]charge.Each lead [4+/2+] ionaccepts two

andisreducedtoalead[4+/2+]ion.[Oxidation/Reduction]occursatthis

electrode.Itisthereforecalledthe[cathode/anode].Becauseelectronsareremovedfromtheelectrodein

thisway,itischarged[negatively/positively].Theseleadionscombinewith

ions from the sulfuric acid electrolyte to form . Hydrogen ions from the

sulfuricacidelectrolytecombinewith ionsfromtheleaddioxideelectrode

toform .

Overall reactionThe overall reaction of the discharging lead acid battery is the reaction of and

electrodeswith acidtoform

and .Thisisaspontaneous,redoxreactionwhichconvertschemicalintoelectric

energy.• Itisspontaneousbecause .• Itisaredoxreaction:itinvolvesthetransferof fromone

chemicaltoanother.• Itconverts into energyas

.


Charging9Completetheexplanationbyfillingthegapsorchoosingfrom theoptions.Dothisbefore,orafter,butnotduring,watching theanimations.Markduringre-watching.

OverviewWhen the lead acid battery is charging it behaves as a set of

[electrolytic/voltaic] cells. It converts

energyinto energyasa[spontaneous/

non-spontaneous]chemicalreactionisforcedtooccurduetoan

externalpotentialdifferencebeingplacedacrosstwoelectrodes.

To charge a lead acid battery, the lead dioxide electrode must be connected to the [positive/

negative] terminal of an external power source, e.g. another battery. The lead electrode must

be connected to the [positive/negative] terminal of this other battery. This pulls electrons from

the [lead/lead dioxide] electrode and forces electrons into the [lead/lead dioxide] electrode.

This causes the reactions which had occurred in the discharging reaction to take place

[inthesamedirection/inreverse].

AnodeThebatterypullselectronsoutoftheelectrodeconnectedtoits[positive/negative]terminal.Because

of this, electrons are pulled out of the Pb2+ ions in the around

this electrode. This produces [Pb2+/Pb4+] ions. Because the [Pb2+/Pb4+] ions [gain/lose] electrons as

they become Pb4+ ions, [oxidation/reduction] is taking place. This electrode is therefore called

the [anode/cathode]. Notice that in an electrolytic cell, such as this one, the anode is [positively/

negatively] charged.This isopposite to thecaseofavoltaiccell. Inanelectrolyticcell theexternal

chargestheanodepositively,whichforcesoxidationtooccurthere.

CathodeThe external battery [pushes electrons into/pulls electrons out of] the electrode connected

to its negative terminal, charging that electrode [positively/negatively]. This forces lead ions,

of formula , to accept two electrons each, changing them into lead

atoms, of formula . This is called [oxidation/reduction], since it involves

.Grey leadmetal is formedthroughthisreductionreaction.The

electrodeatwhichreductionhappensiscalledthecathode.Thereforeinanelectrolyticcell,suchas

thisone,the[positively/negatively]chargedelectrodeisthecathode.

Overall reactionTheoverall reactionof thecharging leadacidbattery is thereactionof ions in

leadsulfatetoform atthecathodeand attheanode.

Thisisanon-spontaneous,redoxreactionwhichconvertselectricalintochemicalenergy.

• Itisnon-spontaneousbecause .

• Itisaredoxreaction:itinvolvesthetransferof fromonechemical

toanother.

• Itconverts into energyas

.


CHLOR-ALKALI

Overview1Complete/choosefromtheoptionstosummarisethepurposeandprocessofthechlor-alkaliindustry.

Input: (brine)

Outputs: : (g) : (aq) Hydrogen:H2(g)

Uses:

2Complete/choosefromtheoptionstosummarisethetypesofchlor-alkalicells.

Membrane Diaphragm Mercury

Cathode material carbon carbon

Input

Oxidation reaction at anode

Reduction reaction at cathode

reducedto + .

SincethereareNa+ionspresenttoo,canbeproduced.

reducedto,whichthen

reactswith toform +

What divides the electrolyte into two half cells?

Disadvantages

PowerSource

-+

ANODE:


CATHODE:


[Electrolytic/voltaic]cell

Converts energy energyasapotentialdifference,placedacrosstwoelectrodes,forcesa[spontaneous/non-spontaneous]chemicalreactiontooccur.

[positive/negative]ionsattracted


3Choosefromtheoptionsforanelectrolytic cell.

ELECTROLYTIC CELL

Anode Cathode



4Circlethecorrectoption(True/False)foreachofthefollowing,referringtoanelectrolytic cell.

ELECTROLYTIC CELL:

aAbatterymakesoneelectrodepositiveandtheothernegative,andthiscausesachemical reactiontooccur. [True/False]b A chemical reaction occurs, and this causes one electrode to be made positive and theothernegative. [True/False]c As oxidation happens, chemicals lose electrons, which then go onto the anode, makingitpositive. [True/False]dThebatterymakestheanodepositive,andthismakeschemicalsloseelectronsthereasthebatterysuckselectronsawayfromthem,causingoxidationtohappen. [True/False]eAsreductionhappens,chemicalsacceptelectrons,takingthemfromthecathode,causingittobecomenegative. [True/False]f The battery makes the cathode negative, and this makes chemicals gain electrons there,causingreductiontohappen. [True/False]

5LinkeachelementfromColumnAwithitscorrespondingelementinColumnB.WritetheletterfromAnexttoeachiteminBinthelastcolumn.

Column A Column B A

aanode colour-remover

bcathode asiteatwhichtheredoxreactionsofanelectrochemicalcelloccur;oftenarod

celectrode ahalfreactioninwhichonechemicalloseselectrons,donatingthemtoanotherchemical

delectrolyte ahalfreactioninwhichonechemicalgainselectronsfromanotherchemical

eoxidation anelectrodeatwhichoxidationoccurs

freduction akindofreactioninwhichelectronsaretransferredfromareducingagenttoanoxidisingagent

gredox attractedtowater

hsoap anionicsolution,thereforeabletoconductelectricity

ihydrophilic repelledbywater

jhydrophobic anelectrodeatwhichreductionoccurs

kbleach anorganicchemicalwhichisabletomakefatdissolve

lchlorine(Cl2) astrongalkali;canbeusedtomakesoap;causticsoda

msodiumhydroxide asubstancewhichkillsgerms

ndisinfectant adensegreengasusefulasbleachanddisinfectant


Membrane Cell6Completetheexplanationbyfillingthegapsorchoosing fromtheoptions.Dothisbefore,orafter,butnotduring, watchingtheanimations.Markduringre-watching.

Cell compositionThe membrane cell is a(n) [electrolytic/voltaic] cell. It

consists of an external power supply (a battery), two

, and . The cell

is divided into two halves. The two halves are separated

by a semi-permeable membrane. Semi-permeable means

.

Electrolyte serves as the electrolyte for the anode's half reaction. An electrolyte is

.

Brineconsistsof dissolvedinwater.Whensodiumchloridedissolvesin

water,itspositivelycharged[sodium/chloride]ionsareseparatedfromitsnegativelycharged[sodium/

chloride]ions,andeachionissurroundedby .

AnodeThe battery creates a across the electrodes. The

positive terminal of the battery [pulls electrons away from/pushes electrons into] the electrode

connected to it, charging the electrode [positively/negatively]. This attracts the [positively/negatively/

neutrally]charged[sodium/chloride]ionsinthebrine.Whenthesereachtheelectrode,thebattery[pulls

anelectronawayfrom/pusheselectronsinto]eachofthem.Thisconvertsthemfrom[positively/negatively/

neutrally]chargedchlorideionsinto[positive/negative/neutral]chlorineatoms.Theseareunstable,so

theybondcovalentlywithoneanotherinpairs,formingdiatomicmoleculesof .This

iswhatweoftenmeanwhenwerefertochlorine.Chlorineisadensegreengaswhichbubblesaway

fromthiselectrodeandiscollected.Chlorinewasformedaschlorideionswerestrippedofelectrons,

sowecall thishalf reaction[oxidation/reduction],which is the[gain/loss]ofelectrons.Each[chlorine

atom/chlorideion]losesoneelectrontochangeitintoa[chlorineatom/chlorideion].Theelectrodeat

whichoxidationoccurs iscalled the [cathode/anode]. Inanelectrolyticcell,suchas this, thebattery

chargestheanode[positively/negatively].

CathodeThesemi-permeablemembraneallows[positively/negatively]chargedsodium[ions/atoms]throughinto

theotherelectrolytichalf-cell.Theelectrode in thishalf-cell isconnected to thenegative terminalof

the battery. The battery [pulls electrons away from/pushes electrons into] it, charging the electrode

[positively/negatively/neutrally]. This causes water molecules to react at this electrode. The water

molecules[lose/accept]theelectrons.Wesaythewateris[oxidised/reduced].Theseelectronscause

watertochangeinto gas(H2)and[positively/negatively/neutrally]chargedhydroxyl

ions(OH-).Thesehydroxyl ionsaredissolvedinwater,asarethesodiumionswhichmovedthrough

themembrane. Sodium ions and hydroxyl ions are therefore present in the solution.We call this a

sodiumhydroxidesolution.Theelectrodeatwhichreductionoccurs iscalledthe[cathode/anode]. In

anelectrolyticcell,suchasthis,thebatterychargesthecathode[positively/negatively].


PETROCHEMICALS

Distillation1Whyisdistillationimportantinthe

petrochemicalindustryfollowingthe

Fischer-Tropschreaction?

2Completetheexplanationbyfillingthegapsor

choosingfromtheoptions.Dothisbefore,or

after,butnotduring,watchingtheanimations.

Markduringre-watching.

Distillation is the separation of a mixture into its components by using their differences in

points.Boilingpointisthe atwhichasubstance

boils.Thisisalsothetemperatureatwhichit[freezes/melts/condenses/sublimes].Duringcondensation,a

substancechangesfrom to .Long-chainedhydrocarbonscondense

at[higher/lower]temperaturesthanshort-chainedhydrocarbons.

A distillation columnhas different temperatures throughout its height. At the bottom it is very [cold/

hot]. It gets cooler and cooler [higher up/lower down]. The hydrocarbon mixture formed by the

Fischer-Tropschprocessisheatedtoover350C,makingall itscomponentsvaporise,that is,turnto

.Thishotmixtureisfedintothebottomofthe column.

Even though the temperature at the bottom of the column is hot, it is not hot enough to keep the

[shortest/longest]-chainedhydrocarbons in thegaseousphase.They andsink

to the bottom. These hydrocarbons havemore than 20 carbon atoms permolecule. They are then

ledoff.Theymaybeused, forexample in ,or theymaybesentback to the

tobesplitintoshorterchains.

The[shorter/longer]hydrocarbons,still inthe phase,rise.Astheydosothey

cometocoolerpartsofthedistillationcolumn.Atabout200C, condenses,and

isledoff. ismadeofamixtureofhydrocarbonshavingfrom12to18carbonatoms

permolecule.Itisusedinsomevehicles.Atabout120C,kerosenecondenses.Keroseneisusedas

fuel.Kerosene isamixtureofhydrocarbonshaving9 to14carbonatomsper

molecule. At 40C, , also called gasoline, condenses. It ismade of a

mixtureofhydrocarbonshavingfrom5to10carbonatomspermolecule.Thisisusedtopowermany

vehicles. At 20C (LPG) condenses.

LPG isoftensold ingasbottlesandmightbeused ingasheatersorstoves. Itcontainsvery [short/

long]hydrocarbonchainswhichhaveonly3or4carbonatomspermolecule.Evensmallermolecules,

consistingofonly1or2carbonatomspermolecule,form .Thisexits

atthetopofthedistillationcolumn,stillinthe phase.

Sobycoolingtheheatedhydrocarbonmixturetodifferent ,itisseparatedinto

itscomponentsaseachcomponent atadifferenttemperature,andthereforea

different ,inthedistillationcolumn.Asimilarprocessisusedintheseparation

ofcrudeoil into itscomponents.The temperaturesusedandproducts formedwould,however,differ

slightlyfromthosegivenhere.


Hydrocracker3Whatisthepurposeofthehydrocracker?

4Whichchemical,inthepresenceofacatalyst,cracksthechains?

Methane, Ethane, Ethene, Wax5Givetheformulaeof: a.Methane b.Ethane c.Ethene

6Ticktherelevantblocksinthistabletoshowtheclassificationofthesechemicals.

Chemical Hydrocarbon? Alkane? Alkene? Polymer?

Methane

Ethane

Ethene

Wax

General7LinkeachelementfromColumnAwithitscorrespondingelementinColumnB. WritetheletterfromAnexttoeachiteminBinthelastcolumn.

Column A Column B A

ahydrocarbons bondsbreak

balkanes asingleunit

calkenes energyneededtostartareaction

dadsorbed consistsofalongchainofrepeatedunits

edissociate consistofonlyhydrogenandcarbonatomsbondedtogether

fintramolecular theprocessbywhichmonomersbondwithoneanother

gpolymer attachesto

hmonomer hydrocarbonswithonlysinglebonds

ipolymerisation betweentwoatomswithinamolecule

jcatalyst hydrocarbonswithadoublebondinthem

kactivationenergy achemicalwhichspeedsupareactionwithoutitselfbeingpermanentlychangedbythereaction

Catalysts8Completetheexplanationbyfillingthegapsorchoosingfromtheoptions.Dothisbefore,or after,butnotduring,watchingtheanimations.Markduringre-watching.

A catalyst speeds up a reaction without itself being permanently by the

reaction. It serves as a site for a reaction to take place. Reactants are

ontoacatalystsurface.Theythen ,breakinginto

their component atoms as their [inter/intra]molecular bonds break. The loosened [molecules/atoms]

canthenbondwithotheratomstoforma[reactant/product].Thecatalystallowsthisreactiontooccur

moreeasilythanifitwasn'tthere.Reactantscanonlybondwithoneanotheriftheycanhitagainstone

anotherwithenough andtheright tostaytogether.We

say theyneed energy inorder tostart them reacting.But ifacatalystholds

thereactants inplacetomakereactingeasier, thereactantsneed[more/less]energytogettoreact.

Inotherwords, a catalyst [reduces/increases] the energyneeded to causea

reaction.Becauseofthis,thereactionwilloccurmore[slowly/quickly]withacatalystthanwithoutone.


FERTILISERSMEMO

Overview1Whyisnitrogenimportanttoplants?Nitrogen is found in all proteins, and so it is an essential nutrient.2.Inwhatformscanplantsabsorbnitrogen?

Dissolved urea, nitrate, nitrite and ammonium ions.3Completetosummarisetheindustrialprocesses.

Process Reactants Products of step 1

Products of step 2

Final products

Haber N2 + H2 notapplicable NH3

Ostwald NH3 + O2 NO NO2 HNO3

Contact S + O2 SO2 SO3 H2SO4

Haber Process4WhatisthepurposeoftheHaberProcess?Toproduce ammonia (NH3) from nitrogen (N2) and hydrogen (H2).5WriteabalancedequationfortheHaberProcess'sreversiblereaction.N2 + 3H2 2NH3

6Namesomeusesofammonia.As a cleaning agent. As a coolant in some air conditioners. To manufacture nitrogen fertilisers.7Nametwoconditionswhichmustbemetforareactiontoreachequilibrium.-reversible reaction-closed system8Nametwocharacteristicsofequilibrium.-rates of forward and reverse reactions are equal to one another-the concentrations of reactants and products remain constant

9IntheHaberProcessanironoxidecatalystisusuallyused.Rutheniumcanalsobeused.Whatdoesacatalystdotoareaction,andhowdoesitdothis?It speeds up a reaction by lowering its activation energy. It does this by serving as a binding site on which the reaction can occur.10Circlethecorrectoption(True/False)foreachofthefollowing.iAcatalystspeedsuptheHaberProcess'sforwardreactionmorethanthereverse.[True/False]iiAcatalystwillcausemoreproducttobeformed. [True/False]iiiAcatalystwilldecreasethetimeittakestoreachequilibriumbecauseitspeedsupbothforwardandreversereactions. [True/False]ivAcatalystspeedsbothforwardandreversereactionsequally [True/False]11LinkeachelementfromColumnAwithitscorrespondingelementinColumnB.

WritetheletterfromAnexttoeachiteminBinthelastcolumn.

Column A Column B A

adynamicequilibrium absorbsheat b

bendothermic ameasureoftheaveragekineticenergyofparticles i

cexothermic disturbsequilibrium,favoursincreasedcrowding,moremolecules

e

dLeChatelier'sprinciple 273Kand101,3kPa k

edecreaseinpressure disturbsequilibrium,favoursexothermicreaction g

fincreaseinpressure releasesheat c

gremovingheat astateinwhichforwardandreversereactionsoccuratequalrates

a

haddingheat forceperarea,ingasesrelatedtorateofparticlecollisions

j

itemperature disturbsequilibrium,favoursdecreasedcrowding,fewermolecules

f

jpressure disturbsequilibrium,favoursendothermicreaction h

kSTP whenasystemwhichisinequilibriumisdisturbed,itwillrespondinsuchawayastocounteractthedisturbance

d


Le Chatelier: Effect of pressure

12Completetheexplanationbyfillingthegapsorchoosingfromtheoptions.Dothisbefore,orafter,butnotduring,watchingtheanimations.Markduringre-watching.

Increased pressureAccording to Le Chatelier's principle, when a system which is inequilibriumisdisturbed,itwillrespondinsuchawayastocounteractthe disturbance. An increase in pressure [de/in]creases the crowdingofgaseousmolecules.Thesystemwillrespondby[de/in]creasingtheircrowding.Crowdingisdecreasedingaseswhen[fewer/more]moleculesareformed.IntheHaberProcessthe[forward/reverse]reactionmakesfewer molecules than the [forward/reverse] reaction. In the forwardreaction 2 molecules of ammonia are made from every 4 moleculesof reactants (1 N2 and3 H2molecules). Consequently, an increase inpressuredisturbsequilibriumforawhilebymakingthe[forward/reverse]reactionoccuratahigherrate than the [forward/reverse] reaction.This causes [more/less] ammonia tobe formedand [more/less]nitrogenandhydrogen.Afterawhileanewdynamicequilibriumisreached.Theratesofforwardandreversereactionsareagainequaltooneanother,andtheamountsofreactantsandproductswill[change/remain constant]. However, compared to before the pressure was applied, there will nowbe [more/less]ammoniapresentatequilibrium.Theequilibriumconstantvalue,Kc,however,willbe[higherthan/lowerthan/the same as]itwasintheoriginalequilibrium.

Decreased pressureDecreasingpressure[de/in]creasesthecrowdingofgaseousmolecules.Thesystemwillrespondby[de/in]creasingtheircrowding.Crowdingcanbeincreasedbyforming[fewer/more]molecules.IntheHaberProcess,thatmeansthat forawhile the [forward/reverse] reactionwilloccuratahigherratethanthe[forward/reverse]reaction.Thereversereactionchangesevery2moleculesofammoniainto4molecules(1nitrogenand3hydrogenmolecules).Thiscausestheamountofammoniapresentto[de/in]creaseandtheamountofnitrogenandhydrogento[de/in]crease.Whilethisishappeningthesystem[is/is not]inequilibrium.Afterawhileanewdynamicequilibriumwillbereached, inwhich theratesofboth forwardandreversereactionswillequal oneanother, and theamountsof reactants andproductswill remainconstant.However,compared tobefore thepressurewasdecreased, therewillnowbe [more/less]ammoniapresentatequilibrium.Theequilibriumconstantvalue,Kc,however,willbe[higherthan/lowerthan/the same as]itwasintheoriginalequilibrium.

Optimum pressureIntheHaberProcess,wewanttomakeasmuchammoniaaspossible.Wewantthedynamicequilibriumtobesuchthatalotof[reactant/product]isformed.A(n)[de/in]creaseinpressurewillcausemoreproductstoform.Weneedas[low/high]apressureasitissafeandeconomicaltouse.Wesayweneedtouseanoptimalpressure:thepressureforwhichwegetagoodyieldforareasonablepricewhilestillbeingsafe.Pressuresbetween200and300atmospheresaretypicallyusedintheHaberProcess.


Le Chatelier: Effect of temperature

13Completetheexplanationbyfillingthegapsorchoosingfrom theoptions.Dothisbefore,orafter,butnotduring,watching theanimations.Markduringre-watching.

HeatingHeatingareactionupincreasesthekineticenergyoftheparticles,andsocausesthemtoreactmore[slowly/rapidly]withoneanother.Additionally,heatcanhaveaneffectondisturbing theequilibriumofareaction.

IntheHaberProcesstheforwardreactionis[exo/endo]thermicandthereverseis[exo/endo]thermic.Thismeansthatasnitrogenandhydrogenreactwithoneanothertoformammonia,heatis[absorbed/released], but as ammonia breaks up into hydrogen and nitrogen, heat is [absorbed/released].AccordingtoLeChatelier'sprinciple,whenasystemwhichisinequilibriumisdisturbed,itwillrespondinsuchawayastocounteractthedisturbance.SoifheatisaddedtoasystemintheHaberProcess,the[exo/endo]thermic[forward/reverse]reactionisfavouredto[absorb/release]someofthatheatandso [cool the system back down/heat thesystembackup].Both the forwardand reverse reactionsoccurat[lower/higher]ratesthanbeforetheheatwasadded,duetotheadditionalkineticenergyofalltheparticles,butthe[forward/reverse]reactionwillhavebeenspeededuptoagreaterextentthanthe[forward/reverse]reaction.Soforawhile,thesystemwillnotbeinequilibriumasthe[forward/reverse]reactionoccursmorerapidlythanthe[forward/reverse]reaction.Thiswill[in/de]creasetheamountofammoniapresent,and[in/de]creasetheamountofhydrogenandnitrogen.Afterawhileanewdynamicequilibriumisreached.Theratesofforwardandreversereactionsareagainequaltooneanother,andtheamountsof reactantsandproductswill remainconstant.However,compared tobefore theheatwasadded,therewillnowbe[less/more]ammoniapresentatequilibrium.Anewequilibriumconstant,Kc,[higherthan/lower than/thesameas]thatoftheoriginalequilibrium,isreached.

CoolingCoolingasystemthatisinequilibriumhastwoeffects.Firstly,by[de/in]creasingthekineticenergyofallthemolecules,it[reduces/increases]theratesofboththeforwardandreversereactions.Secondly,ithastheeffectofdisturbingtheequilibriumbyfavouringthe[exo/endo]thermicreactionuntilanewequilibriumisreachedwith[thesame/a different]equilibriumconstant.

IfheatisremovedfromasystemintheHaberProcess,the[exo/endo]thermic[forward/reverse]reactionisfavouredto[coolthesystembackdown/heat the system back up].Forawhile,thesystemwillnotbe in equilibrium as the [forward/reverse] reaction occursmore rapidly than the [forward/reverse]reaction. This will [in/de]crease the amount of ammonia present, and [in/de]crease the amount ofhydrogenandnitrogen.Afterawhileanewdynamicequilibriumisreached.Theratesofforwardandreverse reactions are again equal to one another, and the amounts of reactants and products willremainconstant.However,comparedtobeforethesystemwascooled,therewillnowbe[less/more]ammoniapresentatequilibrium.Anewequilibriumconstant,Kc,[higher than/lowerthan/thesameas]thatoftheoriginalequilibrium,isreached.


Optimum temperatureIntheHaberProcess,wewanttogetahighammoniayield.Wewanta dynamic equilibrium which makes as much ammonia product aspossible.Consequently,weneedtouseafairly[high/low]temperature.However,thiscausesaproblem,namelyit causes both reactions to be slow, and so it takes a long time for equilibrium to be reached.Therefore,acompromiseismade,andatemperatureofapproximately450Cisoftenused.

Units of pressure and temperature14Completeforunitsofpressure.

Unit Pressure at sea level at 0C

Name Symbol

bar bar 1 bar

atmospheres atm 1 atm

kilopascals kPa 101,3 kPa

millimeters mercury mm Hg 760 mm Hg

15KelvinistheSI(StandardInternational)unitfortemperature.Completeforconversions.

Temperature in degrees Celsius (C) Temperature in Kelvin (K)

0 273

-273 0

100 373

-27 200

25 298

Ostwald Process16WhatisthepurposeoftheOstwaldProcess?Toproducenitric acid (HNO3)fromammonia (NH3).17HowistheproductoftheOstwaldProcessusefulforthefertiliserindustry?Nitric acid can be used to make nitrate fertilisers.18Whydoesn'titmatterthattheplatinumcatalystusedisveryexpensive?It can be used over and over again because it is not used up. Catalysts speed up reactions without themselves being changed in the process.

Complete.

Step 1 Step 2 Step 3

NH3 +O2platinum

catalyst

NO

NO+O2

NO2

NO2 +H2O

HNO3

Contact Process20WhatisthepurposeoftheContactProcess?Toproducesulfuric acid (H2SO4)fromS + O2.21Namesomeusesofsulfuricacid.manufacture of fertilisers, electrolyte in car batteries, as a dehydrating (a drying) agent22Complete.

Step1 Step2 Step3 Step4

S +O2

SO2

SO2+O2V2O5

catalystSO3

SO3 +H2SO4

H2S2O7

H2S2O7 + H2O

2H2SO4


BATTERIESMEMO

Types of batteries1Complete/choosefromtheoptionstosummarisethetypesofbatteries.

Primary Secondary

Rechargeable? [rechargeable/non-rechargeable] [rechargeable / non-rechargeable]

Voltaic/Elec-trolytic?

[only voltaic/voltaicandelectrolytic] [onlyvoltaic/voltaic and electrolytic]

Namesomeexamples

Leclanche (zinc-chloride / dry) cell, mercury cell, alkaline cell

Lead acid, nickel-cadmium, nickel-metal hydride and lithium ion

Voltaic cells2Onthefollowingdiagram: aAddtheselabels:electrolyte,saltbridge,+electrode,-electrode bComplete/choosefromtheoptionstosummarisethecompositionofavoltaiccell.

3Answerconcerningthesaltbridge:aWhatisitspurpose?It completes the electric circuit and it prevents a build-up of charge in either half-cell, by allowing the movement of ions between them.bWhatkindofsubstancemustitbemadeof?Ionic solutioncWhymustitbemadeofthistypeofsubstance?Ionic solutions consist of charged particles (ions) which are free to move under the influence of a potential difference, therefore they can conduct electricity.

4Choosefromtheoptionsforavoltaiccell.

VOLTAIC CELL

Anode Cathode



5Circlethecorrectoption(True/False)foreachofthefollowing,referringtoavoltaic cell.aAbatterymakesoneelectrodepositiveandtheothernegative,andthiscausesachemicalreactiontooccur. [True/False]bAchemicalreactionoccurs,andthiscausesoneelectrodetobemadepositiveandtheothernegative. [True/False]cAsoxidationhappens,chemicalsloseelectrons,whichthengoontotheanode,makingitnegative. [True/False]dTheanodeismadetobenegative,andthismakeschemicalsloseelectronsthere,causingoxidationtohappen. [True/False]eAsreductionhappens,chemicalsacceptelectrons,takingthemfromthecathode,causingittobecomepositive. [True/False]

fThecathodeismadetobepositive,andthismakeschemicalsgainelectronsthere,causingoxidationtohappen. [True/False]

[Battery/Voltmeter]

ANODE:

[oxi

da

tio

n/reduction]

CATHODE:

[oxidation/

red

uc

tio

n]

VoltaicCell

Convertschemicalenergy electricalenergyasa[spontaneous/non-spontaneous]chemicalreactioncreatesapotential differenceacrosstwoelectrodes.

Electrolyte

-electrode

Saltbridge

Electrolyte

+electrode


Lead acid battery (Car battery)

Overview6Aleadacidbatteryconsistsof[primary/secondary]cells.7Complete/choosefromtheoptions.

Discharging Charging

[electrolytic/voltaic]cells [electrolytic/voltaic]cells

[produces/requires]electricalenergy [produces/requires]electricalenergy

Chemical reaction[spontaneous/non-spontaneous] [spontaneous/non-spontaneous]

[exothermic/endothermic] [exothermic/endothermic]

Energy conversion chemicalenergy electricalenergy electricalenergy chemicalenergy

Anode [Pb/PbO2] [Pb/PbO2]

Oxidation reaction Pb Pb2+ + 2e- PbSO4 + 2H2O PbO2 + 4H+ + SO4

2- + 2e-

Cathode [Pb/PbO2] [Pb/PbO2]

Reduction reaction PbO2 + 4H+ + SO42- + 2e-

PbSO4 +2H2OPb2+ + 2e- Pb

Net redox reaction PbO2 + Pb + 4H+ + 2SO42-

2PbSO4+ 2H2O2PbSO4 + 2H2O PbO2 + Pb + 4H+ + 2SO4

2-

Discharging8Completetheexplanationbyfillingthegapsorchoosingfromtheoptions. Dothisbefore,orafter,butnotduring,watchingtheanimations.Mark duringre-watching.

OverviewWhen the leadacidbattery isdischarging it behavesasasetof [electrolytic/voltaic] cells. Each lead acid battery consists of six cells. Only one of these is shown here. Eachcellconvertschemicalenergyintoelectricalenergy,asa[spontaneous/non-spontaneous]chemicalreaction [requires/creates]apotentialdifferenceacross twoelectrodes.A leadacidbatteryhasoneelectrodemadeofleaddioxideandanotheroflead.Theseareinsideasulfuricacidelectrolyte.

AnodeLead atoms in the lead electrode are [oxidised/reduced]: they [gain/lose] two electrons each. Thischanges them into [positively/negatively/neutrally] charged lead [atoms/ions] of formulaPb2+.Since[oxidation/reduction]occursatthiselectrode,wecallittheanode.ThePb2+ionsmoveawayfromtheelectrode,leavingtheelectronstheyhadjustlostbehindontheelectrode.Thismakesthiselectrode,the anode, [positively/negatively/neutrally] charged, creating apotential difference between it andthe other electrode, which is positive relative to it. This causes electricity to flow between the twoelectrodes.

CathodeElectrons move from the [lead/lead dioxide] anode to the [lead/lead dioxide] cathode. There theelectronsare [accepted/released]bypositivelycharged lead ions in the leaddioxideelectrode.Theleadionsherehavea[4+/2+]charge.Eachlead[4+/2+]ionacceptstwoelectronsandisreducedtoalead[4+/2+] ion.[Oxidation/Reduction]occursatthiselectrode.It isthereforecalledthe[cathode/anode]. Because electrons are removed from the electrode in this way, it is charged [negatively/positively].Theseleadionscombinewithsulfate ionsfromthesulfuricacidelectrolytetoformlead sulphate. Hydrogen ions from the sulfuric acid electrolyte combine with oxide ions from the leaddioxideelectrodetoformwater.


Overall reactionThe overall reaction of the discharging lead acid battery is the reaction of lead and lead dioxideelectrodeswithsulfuricacid to form lead sulfateandwater.This isaspontaneous, redoxreactionwhichconvertschemicalintoelectricenergy.• It is spontaneous because the reaction will occur on its own:you don't need to heat it or

provide an external potential difference to force it to occur. • Itisaredoxreaction:itinvolvesthetransferofelectronsfromonechemicaltoanother.• It converts chemical into electrical energy as the chemical reaction creates a potential

difference across the electrodes.

Charging9Completetheexplanationbyfillingthegapsorchoosingfromtheoptions.Dothisbefore,orafter,butnotduring,watchingtheanimations.Markduringre-watching.

OverviewWhen the leadacidbattery is charging it behavesasasetof [electrolytic/voltaic] cells. It converts electrical energyintochemicalenergyasa[spontaneous/non-spontaneous]chemical reaction is forced to occur due to an externalpotential differencebeingplacedacross twoelectrodes.Tochargealeadacidbattery,theleaddioxideelectrodemustbeconnected to the [positive/negative] terminalofanexternalpowersource,e.g.anotherbattery.The leadelectrodemustbeconnected to the [positive/negative]terminal of this other battery.Thispulls electrons from the [lead/lead dioxide] electrodeand forceselectrons into the [lead/leaddioxide]electrode.Thiscausesthereactionswhichhadoccurred in thedischargingreactiontotakeplace[inthesamedirection/in reverse].

AnodeThebatterypullselectronsoutoftheelectrodeconnectedtoits[positive/negative]terminal.Becauseofthis,electronsarepulledoutofthePb2+ionsinthelead sulfatearoundthiselectrode.Thisproduces[Pb2+/Pb4+]ions.Becausethe[Pb2+/Pb4+]ions[gain/lose]electronsastheybecomePb4+ions,[oxidation/reduction] is taking place. This electrode is therefore called the [anode/cathode]. Notice that in anelectrolyticcell,suchasthisone,theanodeis[positively/negatively]charged.Thisisoppositetothecaseofavoltaiccell.Inanelectrolyticcelltheexternalpower supply (e.g. battery)chargestheanodepositively,whichforcesoxidationtooccurthere.

CathodeTheexternalbattery[pushes electrons into/pullselectronsoutof]theelectrodeconnectedtoitsnegativeterminal,chargingthatelectrode[positively/negatively].Thisforcesleadions,offormulaPb2+,toaccepttwoelectronseach,changingthemintoleadatoms,offormulaPb.Thisiscalled[oxidation/reduction],sinceitinvolvesthe acceptance of electrons.Greyleadmetalisformedthroughthisreductionreaction.Theelectrodeatwhichreductionhappensiscalledthecathode.Thereforeinanelectrolyticcell,suchasthisone,the[positively/negatively]chargedelectrodeisthecathode.

Overall reactionTheoverallreactionofthechargingleadacidbatteryisthereactionofleadionsinleadsulfatetoformleadatthecathodeandlead dioxideattheanode.Thisisanon-spontaneousredoxreactionwhichconvertselectricalintochemicalenergy.• It isnon-spontaneousbecause the reaction will not occur on its own:you need to heat it or

provide an external potential difference to force it to occur.• Itisaredoxreaction:itinvolvesthetransferofelectronsfromonechemicaltoanother.• Itconvertselectricalintochemical energyasa potential difference forces a non-spontaneous

chemical reaction to occur.


CHLOR-ALKALIMEMO

Overview1Complete/choosefromtheoptionstosummarisethepurposeandprocessofthechlor-alkaliindustry.Input:Sodium chloride solution (brine)

Outputs: Chlorine : Cl2(g) Sodium hydroxide : NaOH(aq) Hydrogen:H2(g) Uses: Bleach Soap-making Rocket fuel Disinfectant Water purification Possible alternative Used to make PVC Drain cleaning car fuel Needed for making plastics

2Complete/choosefromtheoptionstosummarisethetypesofchlor-alkalicells.

Membrane Diaphragm Mercury

Cathode material carbon carbon mercury

Input brine (NaCl(aq)) and an electric potential difference (PD)

Oxidation reac-tion at anode

2Cl-(aq) Cl2 + 2e-

Reduction reac-tion at cathode

H2O(l)reducedtoH2(g)+OH-(aq)SincethereareNa+ionspresenttoo,NaOHcanbeproduced.

Na+reducedtoNa,whichthenreactswithH2OtoformNaOH+H2

What divides the electrolyte into two half cells?

a semi-permeable membrane

a semi-permeable diaphragm reduction reaction occurs inside the liquid mercury cathode

Disadvantages diaphragm allows Cl- ions into the reduction cell, contaminating the product with significant amounts of NaCl

mercury is poisonous

3Choosefromtheoptionsforanelectrolytic cell.

ELECTROLYTIC CELL

Anode Cathode



PowerSource

-+

ANODE:

[oxi

da

tio

n/reduction]

CATHODE:

[oxidation/

red

uc

tio

n]

[Electrolytic/voltaic]cell

Convertselectricalenergy chemicalenergyasapotentialdifference,placedacrosstwoelectrodes,forcesa[spontaneous/non-spontaneous]chemicalreactiontooccur.

[positive/negative]ions attracted


4Circlethecorrectoption(True/False)foreachofthefollowingreferringtoanelectrolytic cell.aAbatterymakesoneelectrodepositiveandtheothernegative,andthiscausesachemicalreactiontooccur. [True /False]bAchemicalreactionoccurs,andthiscausesoneelectrodetobemadepositiveandtheothernegative. [True/False]cAsoxidationhappens,chemicalsloseelectrons,whichthengoontotheanode,makingitpositive. [True/False]dThebatterymakestheanodepositive,andthismakeschemicalsloseelectronsthereasthebatterysuckselectronsawayfromthem,causingoxidationtohappen. [True/False]eAsreductionhappens,chemicalsacceptelectrons,takingthemfromthecathode,causingittobecomenegative. [True/False]fThebatterymakesthecathodenegative,andthismakeschemicalsgainelectronsthere,causingreductiontohappen. [True/False]

5LinkeachelementfromColumnAwithitscorrespondingelementinColumnB.Writetheletter fromAnexttoeachiteminBinthelastcolumn.

Column A Column B Aaanode colour-remover kbcathode asiteatwhichtheredoxreactionsofanelectrochemicalcell

occur;oftenarodc

celectrode ahalfreactioninwhichonechemicalloseselectrons,donatingthemtoanotherchemical

e

delectrolyte ahalfreactioninwhichonechemicalgainselectronsfromanotherchemical

f

eoxidation anelectrodeatwhichoxidationoccurs afreduction akindofreactioninwhichelectronsaretransferredfroma

reducingagenttoanoxidisingagentg

gredox attractedtowater ihsoap anionicsolution,thereforeabletoconductelectricity dihydrophilic repelledbywater jjhydrophobic anelectrodeatwhichreductionoccurs bkbleach anorganicchemicalwhichisabletomakefatdissolve hlchlorine(Cl2) astrongalkali;canbeusedtomakesoap;causticsoda mmsodiumhydroxide asubstancewhichkillsgerms nndisinfectant adensegreengasusefulasbleachanddisinfectant l

Membrane Cell6Completetheexplanationbyfillingthegapsorchoosingfromtheoptions.Dothisbefore,orafter,butnotduring,watchingtheanimations.Markduringre-watching.

Cell compositionThe membrane cell is a(n) [electrolytic/voltaic]cell. It consists of an external power supply (abattery), two electrodes, and electrolytes. Thecellisdividedintotwohalves.Thetwohalvesareseparatedbyasemi-permeablemembrane.Semi-permeable means it only allows certain ions through.


AnodeThebatterycreatesapotential differenceacrosstheelectrodes.Thepositiveterminalofthebattery[pulls electrons away from/pushes electrons into] the electrode connected to it, charging theelectrode [positively/negatively]. This attracts the [positively/negatively/neutrally] charged [sodium/chloride] ions in the brine.When these reach the electrode, the battery [pulls an electron away from/pushes electrons into] each of them. This converts them from [positively/negatively/neutrally]chargedchlorideionsinto[positive/negative/neutral]chlorineatoms.Theseareunstable,sotheybondcovalentlywithoneanother inpairs, formingdiatomicmoleculesofCl2.This iswhatweoftenmeanwhen we refer to chlorine. Chlorine is a dense green gas which bubbles away from this electrodeandiscollected.Chlorinewasformedaschlorideionswerestrippedofelectrons,sowecallthishalfreaction[oxidation/reduction],whichisthe[gain/loss]ofelectrons.Each[chlorineatom/chloride ion]losesoneelectrontochange it intoa[chlorine atom/chloride ion].Theelectrodeatwhichoxidationoccursiscalledthe[cathode/anode].Inanelectrolyticcell,suchasthis,thebatterychargestheanode[positively/negatively].

CathodeThe semi-permeablemembrane allows [positively/negatively] charged sodium [ions/atoms] throughintotheotherelectrolytichalf-cell.Theelectrodeinthishalf-cellisconnectedtothenegativeterminalofthebattery.Thebattery[pullselectronsawayfrom/pushes electrons into]it,chargingtheelectrode[positively/negatively/neutrally]. This causes water molecules to react at this electrode. The watermolecules[lose/accept]theelectrons.Wesaythewateris[oxidised/reduced].Theseelectronscausewater to change intohydrogen gas (H2) and [positively/negatively/neutrally] charged hydroxyl ions(OH-).Thesehydroxyl ionsaredissolved inwater,asare thesodium ionswhichmoved through themembrane.Sodiumionsandhydroxylionsarethereforepresentinthesolution.Wecallthisasodiumhydroxide solution. The electrode at which reduction occurs is called the [cathode/anode]. In anelectrolyticcell,suchasthis,thebatterychargesthecathode[positively/negatively].

ElectrolyteBrineservesastheelectrolytefortheanode'shalfreaction.Anelectrolyteisa solution which conducts electricity.Brineconsistsofsodium chloride dissolved inwater.Whensodiumchloridedissolves inwater, itspositivelycharged[sodium/chloride] ionsareseparatedfromitsnegativelycharged[sodium/chloride]ions,andeachionissurroundedbywater.


PETROCHEMICALSMEMO

Distillation1WhyisdistillationimportantinthepetrochemicalindustryaftertheFischer-Tropschreaction? Distillation separates the hydrocarbon mixture resulting from the Fischer-Tropsch reaction into its components, which are more useful once isolated.2Completetheexplanationbyfillingthegapsorchoosingfromtheoptions.Dothisbefore,orafter,butnotduring,watchingtheanimations.Markduringre-watching.

Distillationistheseparationofamixtureintoitscomponentsbyusingtheirdifferencesinboilingpoints.Boilingpointisthetemperatureatwhichasubstanceboils.This is also the temperature at which it [freezes/melts/condenses/sublimes]. During condensation,a substance changes from gas to liquid. Long-chained hydrocarbons condense at [higher/lower]temperaturesthanshort-chainedhydrocarbons.

Adistillationcolumnhasdifferenttemperaturesthroughoutitsheight.Atthebottomitisvery[cold/hot].It gets cooler and cooler [higher up/lower down]. The hydrocarbonmixture formed by the Fischer-Tropschprocessisheatedtoover350C,makingallitscomponentsvaporise,thatis,turntogas.Thishotmixtureisfedintothebottomofthedistillation column.

Eventhoughthetemperatureatthebottomofthecolumnishot,itisnothotenoughtokeepthe[shortest/longest]-chainedhydrocarbonsinthegaseousphase.They condenseandsinktothebottom.Thesehydrocarbonshavemorethan20carbonatomspermolecule.Theyarethenledoff.Theymaybeused,forexampleinwax,ortheymaybesentbacktothehydrocrackertobesplitintoshorterchains.

The[shorter/longer]hydrocarbons,stillinthegaseousphase,rise.Astheydosotheycometocoolerpartsofthedistillationcolumn.Atabout200C,dieselcondenses,andisledoff.Dieselismadeofamixtureofhydrocarbonshavingfrom12to18carbonatomspermolecule.Itisusedinsomevehicles.Atabout120C,kerosenecondenses.Keroseneisusedas jetfuel.Keroseneisamixtureofhydrocarbonshaving9to14carbonatomspermolecule.At40C,petrolalsocalledgasoline,condenses.Itismadeofamixtureofhydrocarbonshaving from5 to10carbonatomspermolecule.This isusedtopowermanyvehicles.At20Cliquid petroleum gas(LPG)condenses.LPGisoftensoldingasbottlesandmightbeusedingasheatersorstoves.Itcontainsvery[short/long]hydrocarbonchainswhichhaveonly3or4carbonatomspermolecule.Evensmallermolecules,consistingofonly1or2carbonatomspermolecule,formfuel gas.Thisexitsatthetopofthedistillationcolumn,stillinthegaseousphase.

So by cooling the heated hydrocarbon mixture to different temperatures, it is separated into itscomponentsaseachcomponentcondensesatadifferenttemperature,andthereforeadifferentheight,inthedistillationcolumn.Asimilarprocessisusedintheseparationofcrudeoilintoitscomponents.Thetemperaturesusedandproductsformedwould,however,differslightlyfromthosegivenhere.

Hydrocracker3Whatisthepurposeofthehydrocracker? To break long hydrocarbon chains into shorter chains when these are needed.4Whichchemical,inthepresenceofacatalyst,cracksthechains? Hydrogen


Methane, Ethane, Ethene, Wax5Givetheformulaeof:a.MethaneCH4 b.EthaneC2H6c.EtheneC2H4

6Ticktherelevantblocksinthistabletoshowtheclassificationofthesechemicals.

Chemical Hydrocarbon? Alkane? Alkene? Polymer?

Methane

Ethane

Ethene

Wax

General7LinkeachelementfromColumnAwithitscorrespondingelementinColumnB.WritetheletterfromAnexttoeachiteminBinthelastcolumn.

Column A Column B A

ahydrocarbons bondsbreak e

balkanes asingleunit h

calkenes energyneededtostartareaction k

dadsorbed consistsofalongchainofrepeatedunits g

edissociate consistofonlyhydrogenandcarbonatomsbondedtogether a

fintramolecular theprocessbywhichmonomersbondwithoneanother i

gpolymer attachesto d

hmonomer hydrocarbonswithonlysinglebonds b

ipolymerisation betweentwoatomswithinamolecule f

jcatalyst hydrocarbonswithadoublebondinthem c

kactivationenergy achemicalwhichspeedsupareactionwithoutitselfbeingperma-nentlychangedbythereaction

j

Catalysts8Completetheexplanationbyfillingthegapsorchoosingfromtheoptions.Dothisbefore,orafter,butnotduring,watchingtheanimations.Markduringre-watching.

Acatalystspeedsupa reactionwithout itselfbeingpermanentlychangedby the reaction. Itservesasabindingsiteforareactiontotakeplace.Reactantsareadsorbedontoacatalystsurface.Theythendissociate,breakingintotheircomponentatomsastheir[inter/intra]molecularbondsbreak.Theloosened[molecules/atoms]canthenbondwithotheratomstoforma[reactant/product].Thecatalystallows this reaction to occurmore easily than if it wasn't there. Reactants can only bondwith oneanotheriftheycanhitagainstoneanotherwithenoughenergyandtherightpositioning/orientationtostaytogether.Wesaytheyneedactivationenergyinordertostartthemreacting.Butifacatalystholdsthereactantsinplacetomakereactingeasier,thereactantsneed[more/less]energytogettoreact.Inotherwords,acatalyst[reduces/increases]theactivationenergyneededtocauseareaction.Becauseofthis,thereactionwilloccurmore[slowly/quickly]withacatalystthanwithoutone.


RESEARCHASSIGNMENT

PurposeTogetlearnerstoextract,process,analyse,andsynthesiseinformation,andtocommunicatetheresultsoftheseprocesses.Theydothisindividuallyandcollaboratively.

Procedure

Estimated time Description Resources

Class time: 1 lesson

Explaintheassignmenttothelearners. Dividelearnersintogroupsoffourmemberseach. Assignanindustrytoeachgroup. Giveeachgrouptheiroverarchingcontroversialquestion

(below),andallowthemtoconductaninitialbrainstormonthisquestion,intheirgroups.

Assignanumbertoeachlearner. Giveeachlearnerthelearnersheetsandguidingquestionscor-

respondingtotheirindustryandlearnernumber.

Instructions(p.34)

Overarchingcon-troversialques-tions(below)

Guidanceques-tions(p.34)

Learnersheets(seep.34forlist)

Homework: 2 hours

Learnersreadandsummarisetheinformationassignedtothem. Theyanswertheirguidingquestionsinrough.

Class time: 2 lessons

Learnersshareinformationwithoneanother. Theydrawagroupmindmap. Learnersdiscussthegroupquestions,givenintheguidance

table(p.34),andagreeontheiranswertotheoverarchingcon-troversialquestion.

Largesheetsofpa-per(A3,A2orA1)

Groupguidancequestions(p.34)

Homework:2-4 hours

Learnerspreparetopresentapresentation/writeareport. Notes:reportsandpresentations(pp.35-36)

Class time: 2 lessons

Eachlearnerpresentsasectionofapresentation/writesasec-tionofareport,correspondingtotheirguidingquestions(p.34),andrelatedtotheirgroup'soverarchingcontroversialquestion(below).

Collaborativelylearnersprovideintroductoryandconcludingstatementsintheirpresentation/report,whichanswerstheoverarchingcontroversialquestion,andlinkstheindividuals'argumentstothis.

Theteachermarksthiswork.

Rubrics(pp.36-38)

Overarching controversial questionsDoyouagree/disagree/partiallyagreewiththesestatements?Justifyyouropinion.

The Fertiliser IndustryIn the future fewer South Africanswill be able to live in cities because inorganic fertilisers are notsustainable.

The Battery IndustryBatterytechnologyhasalreadychangedourlifestyleshugely.Inthefuturebatteriesaregoingtohaveanevenbiggereffectonus.

The Chlor-alkali IndustryChlor-alkali cells ingeneral,and themembranecell inparticular,affectpeople's livesmainly for thebetter.

The Petrochemical IndustrySASOLhascontributedsignificantlytoSouthAfrica'sdevelopmentandprosperityinthepast,andwillcontinuetodosointhefuture.


Learner instructionsYouwillworkinagroupoffourlearners.Yourgroup'staskistoansweroneofthecontroversialquestionsonp.33.Youwilldosobyeachwritingpartofaresearchreport/presentingpartofanoralpresentation,andcollaborating,asagroup,onotherparts. 1Eachlearnerinyourgroupshouldhaveanumber.Takethelearnersheets,andnotetheguidingquestions, correspondingtothatnumber(seetablebelow). 2Readyourlearnersheets,andansweryourguidingquestionsinrough. 3Sharewhatyouhavelearntwithyourgroupmembers.Drawagroupmindmap.Discussthegroupguidancequestions(seetablebelow).Discussyourcontroversialquestion. 4Gothroughthenotesonpages35-36andrevisetheinformationrelevanttoyourtopic.Yourteachermaytellyoutoomitcertainheadingsintheresearchreportiftimeislimited.Notetherubrics. 5Writeareport/giveanoralpresentation.Collaborativelyproducetheintroductionandconclusion.Individuallyproducetheworkrelatedtoyourparticularsection.

Guidance

Industry Learner Guidance Learner sheets

1 Howhasthefertiliserindustrydeveloped?Whereisitgoing?Isitsustainable? F2,F8,F92 Howhavewedevelopedfasterwaystoprovidewhatplantsneedtogrow?Whyhasourneed

forfertilisersincreased?Whataretheconsequencesofthis?F4,F5,F7

3 Theworldneedsmorefarmers.Whatdofarmersneedtoknowaboutfertilisersandfarmingtobecomefinanciallysuccessfulandproducegoodcrops?

F1,F3,F10

4 Doesmanufacturingfertilisersnowcreateproblemsforthefuture?Howdoesthefertiliserindus-tryaffecttheenvironment?Isitsustainable?

F6,F11,F12

group Whatdofertilisershavetodowithpeoplelivingincities?Whatareinorganicfertilisers?Aretheysustainable?Why/whynot?Iftheyarenotsustainable,willthisaffectcitylife?Why?/Whynot?

1 Explaintheworkingsofanelectrochemicalcell.Howhavebatteriesdevelopedovertime?Howdotheyaffectourlives?

B1,B2,B10

2 Comparebatterytypes.Howdoweuseeach?Discussthestrengthsandweaknessesofeach.Howdoyoupredictbatterieswilldevelopinthefuture?

B3,B4,B6

3 Differentbatterytechnologieshavedifferentusesandlimitations.Whatarethechallengesthatthedifferenttechnologieshavefacedandhowhavetheytriedtodealwiththese?Whyhavesomanydifferenttechnologiesbeendeveloped?

B5,B7,B8

4 Howcanbatterysustainabilitybeimproved?Refertorecycling,batteryalternativesandcorrectbatteryhandling,useanddisposal.

B9,B11,B12

group Howhasbatterytechnologyalreadychangedourlifestyles?Isitsustainable?Whatpossibilitiesarethereforthefuture?Doyouthinkthesepossibilitieswillaffectusmuch?Why/whynot?

1 Howissaltelectrolysedtoformproducts?Whataretheconsequencesofthisprocess?Whohasbenefited?How?Whohasbeenharmed?How?

C1,C11,C12

2 Salt,causticsodaandmanysoapscontainsodium.Whatotherlinkscanbedrawnbetweenthesethreesubstances?Explainthehistory,sourcing,productionandusesofeach.Highlightthelinksbetweenthethree.

C2,C6,C7

3 Chlorineisfoundinionicforminsalt.Hydrogenisbondedtooxygeninwater.BothClandHarecommonelementsthataffectoureverydaylives.Howaretheseelementsused?Whyaretheysoimportanttous?

C3,C4,C5

4 Discusssimilarities,differences,strengthsandweaknessesofthevariouscellsusedtoelectro-lysebrine.Whyhaveseveraltechniquesbeendeveloped?

C8,C9,C10

group Inwhatwaydochlor-alkalicellsimproveourlives?Dotheyhaveanynegativeeffects?Howdoesthemembranecelldifferfromtherest?Doesitimproveourlivesmorethantheothercellsdo?

1 Comparepetrolanddieselreferringtotheirstructuresandtheireconomicviabilityasfuels.Howdoesourdependenceontheseaffecttheenvironment?

P1,P5,P6

2 Whydoesthepetrochemicalindustryconsistofsomanydifferenttypesofindustrialprocesses?Identifysomeoftheseprocesses.Explainhowtheywork.Whatproductsareformed?Whataretheproducts'uses?

P4,P8,P9

3 Fossilfuelsarenaturalsourcesofenergy.Givetwoexamplesoffossilfuels.Explainwhattheyareandhowweobtainthem.Howdotheyaffectourlives?

P2,P3,P7

4 Thepetrochemicalindustryisbigbusiness.Howandwhyisthisso?WhoaretheroleplayersinSouthAfricaandwhyaretheysoinfluentialineverydaylife?

P10,P11,P12

group HowhasanddoesSASOLcontributetoSouthAfrica'sdevelopmentandprosperity?Istheindustrysustainable?Whatchangesinenergyusagedoyouthinkmighthappeninthefuture?Why?WillSASOL'scontributiontoSouthAfricachange?Ifso,howandwhy?Ifnot,whynot?

Fertiliser

Battery

Chlor-alkali

Petrochem

ical


Researching and presentation notes

ResearchDo notcopyinformationdirectlyfromyoursources.Thisisplagiarism,whichiswrong.Asyouread,writealistofkeywords.Thenputawayyoursourcesanduseyourkeywordstohelpyoutoexplainwhatyouhaveread,usingyourownwords.Interpretthefindingsandstateconclusions.Formanopinion of your own.Makesuggestionsandrecommendationsofyourown.

Oral presentationImagineyouareteachingtheclassthistopic.Howcanyoubeinteresting and informative?Youcannotcovereverything,socarefullychoose what you will present.Planwhatyouwillsay.Chooseonlyafewmainarguments.Eachargumentshouldconsistof:-aclaim(astatement)and-backing(supporttoconvincepeopletheclaimistrue).Whereappropriate,alsogivecounterarguments(argumentsagainstyourviewpoint),andrebuttalstothese(howyouwouldanswerbackagainstthesecounterarguments).Useappropriatelinking wordstomakeyourargumentclear,logicalandcohesive.Somelinkingwordsyoucoulduseare:firstly,secondly,aswehaveseen,ononehand,ontheotherhand,consequently,therefore,however,because,inthepast,inthefuture,atpresent,instead,eventhough,insummary.Practiceyourpresentation.Speak,don'tread.Timeyourself.Listentoyourself.Areyouinterestingandclear?Areyouenthusiastic?Areyouspeakingclearlyandconfidently?Besuretomakeeyecontactwithyouraudience.Useappropriatelanguage.Do not readoffnotes.Do not reciteapreparedspeech.Talktotheclassaboutwhatyouhavefoundandwhatyouhavelearnedasifyouareteachingthematerial.

Written reportCheckyourwritingforspellingandgrammarerrors.Checkifyourwritingislogical,clearandcohesive(linkstogetherwell).Correctyourdraftandrewriteit.Makesureyoureferenceyoursources.Seethenotesonhowtodoareferencelist(p.36).

Report headings

Abstract Asummaryofyourmainargument.200wordsorfewer.Noreferences.

Title pageTitle, authors' names, date of completion. Include here which group member was responsible forwhichsection.

Introduction What is the researchquestion?Why is this important?What topicswillbedealtwith,and inwhatsequence?(Howistheargumentwhichfollowsstructured?)

Report of the research project Eachparagraphshoulddealwithonemainidea,orargument.Eachargumentshouldconsistof:-aclaim(astatement)and-backing(supporttoconvincepeopletheclaimistrue).Whereappropriate,alsogivecounterarguments(argumentsagainstyourviewpoint),andrebuttalstothese(howyouwouldanswerbackagainstthesecounterarguments).Useappropriatelinking wordstomakeyourargumentclear,logicalandcohesive.Somelinkingwordsyoucoulduseare:firstly,secondly,aswehaveseen,ononehand,ontheotherhand,consequently,therefore,however,because,inthepast,inthefuture,atpresent,instead,eventhough,insummary.


Conclusion The research question is answered. This answer is supported with a brief summary of thestrongest arguments given in the report. Suggestions for additional research are given.

ReferencesAlistofresourcesused.Formorethanoneauthor,write'&'beforethelastone.

BooksAuthor'ssurname,Initial.(Yearofpublication).Title.Cityofpublication:Publisher.Journals / MagazinesAuthor'ssurname,Initial.(Yearofpublication).Title.Journal,Volume(Number),Pages.Web sourcesAuthor'ssurname,Initial.(Yearofpublication).Title.[Online].AvailablefromURL.[Dateofretrieval].

ExampleBlack,J.(2001).BatterymanufacturersinSouthAfrica.[Online].Availablefromhttp://www.howstuffworks.com/Batteries/SouthAfrica.htm.[22September2010].Naidoo,P.G.(1992).TeachingPhysicalSciencesintheSouthAfricanclassroom.ScienceEducation,1(1),34-36.Smith,D.,Green,R.S.&Gumede,A.(1986).Chemicalsandtheiruses.CapeTown:FirstPublishers.

AppendixInclude:-aglossaryofthetermsrelevanttotheproject.-relevantdiagramsorpictures.-amind maporflowdiagramthatwasusedtoplantheresearchreport.

Rubrics

Oral presentationGroup mark Not

achievedModerate Adequate/

SubstantialOutstanding

Thegrouppresenteditsanswertothecontro-versialquestionclearlyandconvincingly.

0 1 2 3

Thegroupsupporteditsanswertothecontro-versialquestionthoroughlyandlogically.

0 1 2 3

Thecollaborativeandindividualsectionsofthepresentationwerewell integratedand linkedtomakeacohesivewhole.

0 1 2 3

Individual mark

Ahighlyenthusiasticlearner.Thepresentationisinteresting,capturingattention.

0 1 2 3

Accurateinformationwaspresented.Itisclearthatthelearnerhasmasteredthecontent.

0 1 2 3

Argumentsareclearandlogical.Claimsaresupportedthoroughlyandlogically.

0 1 2 3

Counterargumentsandrebuttalsareincludedinafair-mindedmanner.

0 1 2 3

Thelearnerisabletoconverseinascientificlanguage.

0 1 2 3

Thelearnerpresentsthetopicwithoutreading.He/shekeepstotimelimits.

0 1 2 3

Themostimportantandrelevantcontentwaspresented.Thisisdoneinawell-organisedsequence.

0 1 2 3

Total /30


Written report

Criterion Level Descriptors

Abstract (6marks)

(Groupmark)

Noabstractisincludedorabstractisnotappropriateorabstractisrele-vantbutnoneofthestatementsaresatisfactory.

Anyoneof:Researchcon-ceptisstatedclearly.Essentialresearchfindingsaresummarised.Conclusionisstated.Fewerthan200wordsareused.

Anytwoof:Researchcon-ceptisstatedclearly.Essentialresearchfindingsaresummarised.Conclusionisstated.Fewerthan200wordsareused.

Anythreeof:Researchcon-ceptisstatedclearly.Essentialresearchfindingsaresummarised.Conclusionisstated.Fewerthan200wordsareused.

Researchconceptisstatedclearly.Essentialresearchfindingsaresum-marised.Conclu-sionisstated.Fewerthan200wordsareused.

0-1 marks 2-3 marks 4 marks 5 marks 6 marks

Title page (1mark)

(Groupmark)

Notitlepageisincludedortitlepageisinap-propriateortitlepageisincom-plete.

Thefollowingaregiven:Researchreporttitle.Authors'names.Completiondate.Alistofwhichlearnerwasresponsibleforwhichsection.

0 marks 1 mark

Introduction (7marks)

(Groupmark)

Nointroductionorintroductionisinappropriateoritisrelevantbutnotsatisfactory.

Anyoneofthefollowing:Theresearchquestionisgiven.Itisclearwhytheresearchisimportant.Theargumentsequenceismappedout.

Anytwoofthefollowing:Theresearchquestionisgiven.Itisclearwhytheresearchisimportant.Theargumentsequenceismappedout.

Allofthefollow-ing:Theresearchquestionisgiven.Itisclearwhytheresearchisimportant.Theargumentsequenceismappedout.

0-1 marks 2-3 marks 4-5 marks 6-7 marks

Report (20marks)

(Individualmark)

Noreportisincludedorthereportisinap-propriateorthereportisrelevantbutnotsatisfac-tory,orplagia-rismispresent.

Anyoneofthefollowingisap-propriate:Findingsareinlearner'sownwords.Scien-tifictermsandconceptsarecorrectlyused.Resourcesused/consultedarecited.Thereportiswellresearched.Theguid-ingquestionsareansweredthoroughlyandcorrectly.

Anytwoofthefollowingareap-propriate:Findingsareinlearner'sownwords.Scien-tifictermsandconceptsarecorrectlyused.Resourcesused/consultedarecited.Thereportiswellresearched.Theguid-ingquestionsareansweredthoroughlyandcorrectly.

Anythreeofthefollowingareap-propriate:Findingsareinlearner'sownwords.Scien-tifictermsandconceptsarecorrectlyused.Resourcesused/consultedarecited.Thereportiswellresearched.Theguid-ingquestionsareansweredthoroughlyandcorrectly.

Morethanthreeofthefollowingareappropriate:Findingsareinlearner'sownwords.Scientifictermsandconceptsarecorrectlyused.Resourcesused/consultedarecited.Thereportiswellresearched.Theguidingques-tionsareansweredthoroughlyandcorrectly.

0-2 marks 3-6 marks 7-10 marks 11-14 marks 15-20 marks


Argument quality(12marks)

(Individualmark)

Claimsarenotclearandnotthoroughlyandlogicallysupported.Counterargu-mentsandrebuttalsarenotgiven,ornotsuitable.Link-ingwordsarelackingandusedinappropriately.

Anyoneof:Claimsareclearandthoroughlyandlogicallysupported.Coun-terargumentsandrebuttalsaregivenandintegratedwellinacoherent,fair-mindedmanner.Linkingwordsareusedlogi-callytoholdtheargumentcohe-sivelytogether.

Anytwoof:Claimsareclearandthoroughlyandlogicallysupported.Coun-terargumentsandrebuttalsaregivenandintegratedwellinacoherent,fair-mindedmanner.Linkingwordsareusedlogi-callytoholdtheargumentcohe-sivelytogether.

Allthreeof:Claimsareclearandthoroughlyandlogicallysupported.Coun-terargumentsandrebuttalsaregivenandintegratedwellinacoherent,fair-mindedmanner.Linkingwordsareusedlogi-callytoholdtheargumentcohe-sivelytogether.


Conclusion (7marks)

(Groupmark)

Noconclusionisincludedortheconclusionisinappropriateortheconclusionisrelevantbutnotsatisfactory.

Anyoneof:Theresearchquestionisansweredclearly.Thisissupportedbyabriefsummaryofthestrong-estarguments.Suggestionsforfurtherresearcharegiven.

Anytwoof:Theresearchquestionisansweredclearly.Thisissupportedbyabriefsummaryofthestrong-estarguments.Suggestionsforfurtherresearcharegiven.

Allthreeof:Theresearchquestionisansweredclearly.Thisissupportedbyabriefsummaryofthestrong-estarguments.Suggestionsforfurtherresearcharegiven.


References(4marks)

(Groupmark)

Noreferencelistisincluded,ornoneofthesourcesisappropriatelyreferenced.

Anyoneof:Appropriateresourcesarecited.Thereferencelistisappropriatelyextensive.Sourcesareallcorrectlyrefer-enced.

Appropriateresourcesarecited.Thereferencelistisappropriatelyextensive.Some,butnotall,resourcesarecorrectlyreferenced.

Allthreeof:Appropriateresourcesarecited.Thereferencelistisappropriatelyextensive.Sourcesareallcorrectlyrefer-enced.

0 marks 1 mark 2 marks 3-4 marks

Appendix (3marks)

(Groupmark)

Noappendixisincludedortheappendixisinappropriateoritisrelevantbutnotsatisfactory.

Anyoneof:Relevanttermsarecorrectlyexplained.Rel-evantdiagrams/picturesareincluded.Thereisarelevantconceptmap/flowdiagram.

Anytwoof:Relevanttermsarecorrectlyexplained.Rel-evantdiagrams/picturesareincluded.Thereisarelevantconceptmap/flowdiagram.

Relevanttermsarecorrectlyexplained.Rel-evantdiagrams/picturesareincluded.Thereisarelevantconceptmap/flowdiagram.

0 marks 1 mark 2 marks 3 marks

Writing quality (10marks)

(Individualmark)

Thereareverymanygram-matical,spelling,typographicand/orscientificerrors.

Thereareasig-nificantnumberofgrammatical,spelling,typo-graphicand/orscientificerrors.

Thereareafairnumberofgram-matical,spelling,typographicand/orscientificerrors.

Therearefewgrammatical,spelling,typo-graphicand/orscientificerrors.

Therearenogram-matical,spelling,typographic,orscientificerrors.

0-1 mark 2-4 marks 5-6 marks 7-8 marks 9-10 marks

Total /70


Instructions Readtheseinvestigationinstructions,resultsandtheory. Watchtheaccompanyingmovie. Answerthequestions. Performtheinvestigationyourselfforenrichment.

Investigation instructions and results

Apparatus

powersupply 2,2V bulb

leadelectrodes

Chargingcell Dischargingcell

Method• Charging.Chargethecellforvarioustimes.Treatmentsdifferinchargetime:A:1minute B:2minutes C:3minutesD:4minutes E:5minutes F:6minutes• Discharging.Aftereachchargeperiod,connecta2,2Vbulb toallowfordischarge.Measurethe

timeperiodforwhichthebulbshines.

Background theoryAsecondarycellisrechargeable.Whileitisdischargingitbehavesasavoltaiccell.Chemicalenergyis converted into electrical energy. This happens as a spontaneous redox reaction occurs at theelectrodes,causingapotentialdifferencetodevelopacrossthem.

While thecell isbeingcharged itbehavesasanelectrolyticcell.Electricalenergy isconverted intochemical energy. For this to happen, the cellmust be connected to an external power supply. Thiscausesapotentialdifferencetoformacrosstheelectrodes.Thisforcesanon-spontaneouschemicalreactiontooccur.Thischemicalreactionisthereverseofthespontaneousdischargereaction.Inthisway the chemicals are restored to their original state, ready to react spontaneously during the nextdischarge.

CELLCHARGEANDDISCHARGE

connectingwires


Questions

VariablesComplete/Givethe:1Independentvariable.(Cause.Whattheinvestigatormadedifferentbetweenthetreatments.)

2Indicatorofthedependentvariable.(Measurementofeffect.Whattheinvestigatormeasuresto showtheinvestigationoutcome.)

3 variable.A cell's discharge time.(Effect.Differentbetweenthetreatmentsbecausetheyhadbeentreateddifferentlyfromthestart.)

4Controlledvariables(listatleastthree).(Mustbekeptthesamebetweentreatmentsforafairtest.)

Focus question

Complete:5Howdoes affect ? [independentvariable] [dependentvariable]

Hypothesis6Guesswhattheanswertothefocusquestionmightbe.

7Justifyyourhypothesis,referringtothebackgroundtheory.

Table8Circlethecorrectoptionstocompletegeneralrulesfordrawingatable.

Optional Headings

Dependentvariable/ Independent variable /Indicatorofdependentvariable

Dependentvariable /Independentvariable/ Indicator of dependent variable

A

B

C

D

Body9Units(e.g.minors)shouldbegivenonlyinthe[heading/body]ofthetable.10Theabbreviationfortheunitsecondsis[sec/s].

Values showing how investigator treated

treatments differently / Measurements

made to show investigation outcome

Valuesshowinghowinvestigatortreatedtreat-

mentsdifferently/Measurements



11Calculatetheaveragesforeachtreatment.

Theeffectofacell'schargetimeonitsdischargetime

Charge time (min)Time bulb shines (s)

Raw data (3 repetitions) Average

A 1 4,5;4,7;4,6

B 2 6,0;5,9;5,5

C 3 6,4;6,4;6,7

D 4 6,9;6,9;6,9

E 5 7,3;7,9;7,0

F 6 8,1;8,4;7,5

Graph12Representthefindingsgraphically.

Check.Haveyou: Tickifdone:• givenasuitablegraphheading? • plottedtheindependentvariableonthex( )axis? • plottedtheindicatorofthedependentvariableonthey( )axis? • labelledeachaxisandgivenunitswhereappropriate? • accuratelyplotteddatapointswithsmallcircleddots? • drawnasmoothtrendline?

Conclusion13Answerthefocusquestioninyourownwords.

14Completeforashorterwayofwritingtheconclusion.

Increasing [increases/decreases/doesn'taffect][independentvariable]

[dependentvariable]

Discussion15Wasyourhypothesisshowntobecorrectorincorrect?

16Suggestareasonforyourfindings,referringtothebackgroundtheory.


Further investigationDesignanotherinvestigationofyourown,usingtheguidancegivenbelow.Itmusthaveadifferentfocusquestiontothepreviousinvestigation.

VariablesComplete/Givethe:17Independent variable. Dependent variable.A cell's discharge time.

18Controlledvariables.(Mustbekeptthesamebetweentreatmentsforafairtest.) Comparedtothepreviousinvestigation,giveonevariablewhich:amustbeconstantbetweentreatmentshere,butnotpreviously

bmustnotbeconstantbetweentreatmentshere,butmustbepreviously

Focus questionComplete:19Howdoes affect ? [independentvariable] [dependentvariable]

Method20Treatmentsdifferin: :

A: C:

B: D:

21Explainwhatyouwoulddointhisinvestigation.

Table22Fillinheadingsandvaluesshowinghowyouwilltreatthetreatmentsdifferently.Includeunitsinheadingswhereappropriate.Leaveemptyspaceswhereyoucouldfilldatainaftertakingmeasurements.

ABCD


RATEOFELECTROLYSIS

Instructions Readthisinvestigationinformation. Watchtheaccompanyingmoviesectionbysectionasyouanswerthequestions. Performtheinvestigationyourself.

Investigation information

Apparatus Carbonelectrodes.Youcouldgetthesefromdismantledcells. Copperchloridesolutioninabeaker. Apowersupply(e.g.battery)andconnectiveleads.

Background theoryChlorineisadensegreengaswithacharacteristicsharpsmell.Itisaverystrongoxidisingagent,whichmakesitapowerfulbleachanddisinfectant.Chlorinecanbeproducedbytheelectrolysisofchlorine-containing compounds. During electrolysis, a compound may be decomposed into its componentelements.Thishappensaselectricalenergyisconvertedintochemicalenergyinanelectrolyticcell.Anelectrolyticcellconsistsofanexternalpowersupply(e.g.battery)connectedtotwoelectrodeswhichare placed in an electrolyte. The electrodes are conductive rods.An electrolyte is an ionic solutionwhichconductselectricity.Whenanelectricpotentialdifferenceisplacedacrossthetwoelectrodes,a redox reaction occurs at each electrode. This redox reaction decomposes the electrolyte into itscomponentelementsorintosimplercomponentcompounds.

Copperchloridesolution(CuCl2(aq))containschlorideions(Cl-(aq)).Thesecanbeoxidisedtochlorine

molecules (Cl2).This isseenbybubblesofchlorinegas formingat thepositivelychargedelectrode.The electrode where oxidation occurs is called the anode. Copper chloride solution also containscopper ions (Cu2+(aq)). During the electrolytic process, these are reduced to copper atoms, whichprecipitate on thenegatively chargedelectrode.Theelectrodewhere reductionoccurs is called thecathode.Thebluecolourofthecopperchloridesolutionbecomeslighterincolourandthemassofthecathodeincreasesasthecopperionsinsolutionarereducedtocopperwhichgathersonthecathode.

Electrolysisratemeanstheextenttowhichelectrolysisoccursinacertaintime.Itcanbemeasuredbythechangeinreactantsand/orproductspertime.

connectiveleads

copperchloridesolutioninabeaker

powersupply

carbonelectrode


Questions

Planning possibilitiesWatchthemovieintroductionabouttheplanningpossibilitiesoftheinvestigation.Youwanttoinvestigatehowvariousfactorsaffecttherateofelectrolysis.

1Suggestvariousfactorswhichmightaffecttherateofelectrolysisandwhichyoucouldalterinthis investigation.Thesearepossible independentvariables.

2Rate of electrolysisisthedependentvariableforthisinvestigation.

Givepossiblefocus questionsforthisinvestigation.

Thesecanbewrittenintheform:

Howdoes[independentvariable]affect[dependentvariable]?

3Completeforthreepossibleindicatorsofthedependentvariable(rateofelectrolysis).

Indicatorofrateofelectrolysis

IfIsee ,Iwoulddeducethattherateofelectrolysiswashigh

IfIsee ,Iwoulddeducethattherateofelectrolysiswaslow

Watchtherestofthemovie.

Focus question4Givethefocusquestionoftheinvestigationperformedinthemovie.

Howdoes affect ? [independentvariable] [dependentvariable]


Treatments5Describethetreatments.

(giveageneraldescriptionofwhatiscommonbetweenthetreatments) A: B:

C: D:(listspecificdifferencesbetweenthetreatments)

6Inwhichvariabledotheydifferfromoneanother?(Choose.)[Dependent/Independent]

Controlled variables7Listvariableswhichmustbethesamebetweenthedifferenttreatmentsforafairtest.

Results8Tabulatetheresultseithershowninthemovie,or,preferably,fromyourownexperiment.

Rawdatatable:

Electrode mass (g)Initial Final Change

Processeddatatable:

Change in electrode massdue to copper deposition (g)

Check.Haveyou: Tickifdone:• completedthetableheadingssuitably? • headedthefirstcolumnswiththeindependentvariable? • givenunits,whereappropriate,intheheadings,notbody,ofthetable? • filledinalltreatmentdetailsinthefirstcolumn? • filledininitialandfinalmassreadings(processeddatatable) • correctlycalculatedandrecordedmasschangevalues(rawandprocesseddatatables)?



Check.Haveyou: Tickifdone:• givenasuitablegraphheading? • plottedtheindependentvariableonthex( )axis? • plottedtheindicatorofthedependentvariableonthey( )axis? • labelledeachaxisandgivenunitswhereappropriate? • accuratelyplotteddataanddrawnasmoothtrendline



Increasing [increases/decreases/doesn'taffect] [independentvariable]

[dependentvariable]

Discussion12Suggestareasonforyourfindings,referringtothebackgroundtheory.


PROPERTIESOFFLOORWAX

Instructions• Readtheseinvestigationinstructions,resultsandtheory.• Watchtheaccompanyingmovie.• Answerthequestions.• Performtheinvestigationyourselfforenrichment.

Investigation instructions and results

Apparatus• Fourdifferentkindsoffloorpolishpreparedbymixingmoltencandlewaxinparaffinwax. Treatmentsdifferinamountofcandlewaxdissolvedinparaffintomakethepolish:

• A:4gcandlewax/20mlparaffin• B:8gcandlewax/20mlparaffin• C:12gcandlewax/20mlparaffin• D:16gcandlewax/20mlparaffin

• Fourplanks.• Anobjecttoslidedowntheplanks.• Aprotractor.

Method• Smearsomepolishontoeachplank.• Placetheslidingobjectononeplankatatime.• Liftoneendoftheplankgraduallyuntiltheobjectbeginstoslide.• Measuretheangletheplankmakestothehorizontalwheninthisposition.

ResultsTheeffectofapolish'samountofcandlewaxontheamountoffrictionitgives

Mass candle wax / 20ml paraffin (g)Minimum angle causing sliding ( to horizontal)


A 4 16,16,16 16

B 8 20,16,18 18

C 12 26,22,30 26

D 16 46,45,47 46

polish

plank

slidingobject

protractor


Background theoryCandlewax ismadeof long-chainedalkanes,and liquidparaffinofshort-chainedalkanes.Botharesometimes called paraffins, since they are both alkanes. Candle wax can be called paraffin wax.Alkanesarehydrocarbonswithonlysinglebonds.Hydrocarbonsconsistofonlycarbonandhydrogenatoms. Longer chained hydrocarbons have a higher viscosity than shorter chained hydrocarbons.Viscositymeansresistancetoflow.Longchainedhydrocarbonstangleupwithoneanother,makingitdifficultforthemtoflowoveroneanother,makingtheirviscosityhigh.Theirviscositymaybesohighthattheycannotflowatall:theyaresolids,notliquids.

Heatingasolidcanmeltit.Thisdecreasesitsviscosity,changingitfromsolidtoliquid.Whencandlewaxismelted,itcanmixwithparaffin.Thismixtureiscalledasolution.

Friction is a force which resists motion. It results from surfaces rubbing against one another. Theamount of friction is affected by howhard the two rubbing surfaces are pressed together, and howrougheachsurfaceis.Thereforethefrictionbetweenanobjectandthesurfaceitisrestingoncanbereducedbymaking theobject lighter, tilting thesurface,orbymaking thesurfacessmoother.Somepolishmightmakeasurfacesmoother.

Questions

VariablesComplete/Givethe:1Independentvariable.(Cause.Whattheinvestigatormadedifferentbetweenthetreatments.)

2Indicatorofthedependentvariable.(Measurementofeffect.Whattheinvestigatormeasurestoshowtheinvestigationoutcome.)

3 variable.Amount of friction the polish gives.(Effect.Differentbetweenthetreatmentsbecausetheyhadbeentreateddifferentlyfromthestart.)

4Controlledvariables(listatleastthree).(Mustbekeptthesamebetweentreatmentsforafairtest.)


Theory6Whatisfriction?7Howcanfrictionbetweentwosurfacesbereduced?

8Whydowewantpolishwithmorefriction?

9Howdoescandlewaxdifferfromparaffin?

Candlewaxwhereasparaffin .


Graph10Representthefindingsgraphically.Onlyplottheaveragevalues.

Check.Haveyou: Tickifdone:• givenasuitablegraphheading? • plottedtheindependentvariableonthex( )axis? • plottedtheindicatorofthedependentvariableonthey( )axis? • labelledeachaxisandgivenunitswhereappropriate? • accuratelyplotteddatapointswithsmallcircleddots? • drawnasmoothtrendline?

11Itwouldbewrongtomakethisgraph'slinecuttheorigin(0,0).Why?

Interpretation12Circlethecorrectoptiontoanalysethedata.

Amount of candle wax Minimum angle causing sliding Amount of friction polish gives

[more/less]friction

[more/less]friction

13Interprettheresultsinyourownwords.



Increasing [independentvariable]

[increases/decreases/doesn'taffect] [dependentvariable]

a[higher/lower]slidingangleindicateshighwasfoundtocause

a[higher/lower]slidingangleindicateslowwasfoundtocause



Further investigationDesignanotherinvestigationofyourown,usingtheguidancegivenbelow.Itmusthaveadifferentfocusquestionfromthepreviousinvestigation.

VariablesComplete/Givethe:17Independentvariable. Dependentvariable.Amount of friction polish gives.

18Controlledvariables.(Mustbekeptthesamebetweentreatmentsforafairtest.)Comparedtothepreviousinvestigation,giveonevariablewhich:amustbeconstantbetweentreatmentshere,butnotpreviouslybmustnotbeconstantbetweentreatmentshere,butmustbepreviously


Method20Treatmentsdifferin:

A: C:

B: D:

Table21Fillinheadingsandvaluesshowinghowyouwilltreatthetreatmentsdifferently. Includeunitsinheadingswhereappropriate. Leaveemptyspaceswhereyoucouldfillindataaftertakingmeasurements.

A

B

C

D


CELLCHARGEANDDISCHARGEMEMO

Purpose• Learnersareguidedthroughthebasicaspectsofanexperimentalinvestigation.• Learnersplananadditionalinvestigationoftheirown.

Suggested teaching approach


Classtime:1lesson

Explainthenecessarytheoryaboutbatteriesandaboutthescientificmethod.

Showlearnersthemovieorperformtheinvestigationyourself. Discusstheinvestigation.Referto:variables,focusquestion,

hypothesis,results,conclusion,discussion.

CellchargeanddischargemovieWorksheet(p.39)

Homeworktime:hour

Learnersanswerquestions1-16inwriting. Worksheet(p.39)

Classtime:lesson

Gothroughtheanswerstoquestions1-16withthelearners. Conductaclassdiscussiononfurtherinvestigationpossibilities

(questions17-22).Notethatanumberofpossibilitiescouldbecor-rect:notonlytheonesuggestedhere.

MemoWorksheet

Homeworktime:hour

Learnersanswerquestions17-22inwriting. Worksheet

Checkthelearners'work.Additionaltimeshouldbeallowedifyouwanttoperformtheexperimentinclass.

Practical tips Make sure you use a low-voltage (2,2V) bulb. An LED will also work, but takes a long time to

dischargethecell. Allowthecelltochargeforawhilebeforeyoubegincollectingdata.PbO2formsinthistime. Short-circuitthecellbyplacingawireacrosstheelectrodes,beforeeachcharge.

Suggested answers to questions

Variables1Independentvariable.A cell's charge time. (Cause.Whattheinvestigatormadedifferentbetweenthetreatments.)2Indicatorofthedependentvariable.Time bulb shines(Measurementofeffect.Whattheinvestigatormeasurestoshowtheinvestigationoutcome.)3Dependent variable.Acell'sdischargetime.(Effect.Differentbetweenthetreatmentsbecausetheyhadbeentreateddifferentlyfromthestart.)4Controlledvariables(listatleastthree).(Mustbekeptthesamebetweentreatmentsforafairtest.)

concentration of electrolyte (sulfuric acid solution); PD during changing; temperature; distance between electrodes; surface area of electrodes; types of substances used for electrodes and electrolyte

Focus question5Howdoesa cell's charge time affectits discharge time? [independentvariable] [dependentvariable]

Hypothesis6Guesswhattheanswertothefocusquestionmightbe.The learner should give his/her guess.

7Justifyyourhypothesis,referringtothebackgroundtheory. The learner should justify his/her hypothesis, referring to theory.


Table8Circlethecorrectoptionstocompletegeneralrulesfordrawingatable.

Optional Dependent variable / Independent variable / Indicator of dependent variable

Dependent variable / Independent variable / Indicator of dependent variable

A

B

C

D

9Units(e.g.minors)shouldbegivenonlyinthe[heading/body]ofthetable.10Theabbreviationfortheunitsecondsis[sec/s].11Calculatetheaveragesforeachtreatment:

Theeffectofacell'schargetimeonitsdischargetime

Charge time (min)Time bulb shines (s)


A 1 4,5;4,7;4,6 4,6

B 2 6,0;5,9;5,5 5,8

C 3 6,4;6,4;6,7 6,5

D 4 6,9;6,9;6,9 6,9

E 5 7,3;7,9;7,0 7,4

F 6 8,1;8,4;7,5 8,0


Check.Hasthelearner: Tickifdone:• givenasuitablegraphheading? • plottedtheindependentvariableonthex( )axis? • plottedtheindicatorofthedependentvariableonthey( )axis? • labelledeachaxisandgivenunitswhereappropriate? • accuratelyplotteddatapointswithsmallcircleddots? • drawnasmoothtrendline?

Conclusion13Answerthefocusquestioninyourownwords. The longer you charge the battery, the longer the light shines (the longer the battery can discharge). A battery's discharge time is directly proportional to its charge time.14Completeforashorterwayofwritingtheconclusion.

Increasinga cell's charge time[increases/decreases/doesn'taffect] its discharge time.

Discussion15Wasyourhypothesisshowntobecorrectorincorrect?Depends on learner's hypothesis.16Suggestareasonforyourfindings,referringtothebackgroundtheory.

Values showing how investigator treated

treatments differently / Measurements


Values showing how investigator treated treat

ments differently / Measurements



The charging process restores chemicals to the state they need to be in to restart the discharge process. The longer the charging time the more chemicals can be restored to the state needed for the discharge process, and therefore the longer the subsequent discharge time can be. Of course, this is only up to a point. If the battery is already fully charged with all its chemicals restored to the state ready for discharge then charging it longer doesn't help: it won't discharge for longer because it has reached its capacity already.We can also explain this in terms of energy. Charging converts electrical to chemical energy. This chemical energy can then be converted back into electrical energy during discharging. The longer the period of charging, the more electrical energy is stored as chemical energy, and therefore the more chemical energy is present to be able to be converted back into electrical energy during discharging. Again, this is only up to a limit.

Further investigation: Possible answerDesignanotherinvestigationofyourown,usingtheguidancegivenbelow.Itmusthaveadifferentfocusquestiontothepreviousinvestigation.Note that there are other answers which could be correct too.

VariablesComplete/Givethe:

17 Independent variable. A cell's electrolyte concentration Dependentvariable.A cell's discharge time.18Controlledvariables.(Mustbekeptthesamebetweentreatmentsforafairtest.) Comparedtothepreviousinvestigation,giveonevariablewhich:amustbeconstantbetweentreatmentshere,butnotpreviouslythe cell's charge time.bmustnotbeconstantbetweentreatmentshere,butmustbepreviouslythe electrolyte concentration (or whatever learner chose as their dependent variable here).

Focus questionComplete:19Howdoes a cell's electrolyte concentrationaffect its discharge time? [independentvariable] [dependentvariable]

Method20Treatmentsdifferin:electrolyte concentration Note: these values are only suggestions: any reasonable values are acceptable: A: 0,1 M H2SO4(aq) C: 1 M H2SO4(aq) B: 0,5 M H2SO4(aq) D: 1,5 M H2SO4(aq)

21Explainwhatyouwoulddointhisinvestigation. Mix different concentrations of sulfuric acid solutions. Charge each cell for a certain amount of time (e.g. 1 minute). Record the time for discharge for each cell.

Table22Fillinheadingsandvaluesshowinghowyouwilltreatthetreatmentsdifferently. Includeunitsinheadingswhereappropriate. Leaveemptyspaceswhereyoucouldfilldatainaftertakingmeasurements.

The effect of a cell's electrolyte concentration on its discharge time

Electrolyte concentration (M) Time bulb shines (s)

A 0,1

B 0,5

C 1

D 1,5


RATEOFELECTROLYSISMEMO

Purpose• Learners design, perform, and report on an experimental investigation using readily-available

equipment.

Structure• Duringthefirstpartoftheworksheetandmovielearnersexplorenumerousinvestigationpossibilities,

and think through the design of these possible experiments. During the last part of themovie,learnersobservehowtoperformaspecificinvestigation.Afterthis,theyshouldpreferablypracticallyperformthisinvestigation,oranyoftheothervariationstheyhadpreviouslyplanned.Alternatively,theycouldcompletetheworksheetbyreferringtowhatwasdoneinthemovie.

Suggested teaching approachEstimated time Description Resources

Classtime:1lesson

Exploreplanningpossibilities. Discussset-upandtheory. Setupelectrolyticcells.Eitherprescribeaspecificinvesti-

gationtoperform,e.g.thatperformedinthemovie,orgivelearnersthefreedomtoinvestigateanyfeasiblequestionfromthosepreviouslydiscussed.

RateofelectrolysismovieElectrodes,CuCl2,cells,wires,scale

Homework:lesson

Learnersanswerquestions1-7inwriting. Worksheet(pp.43-46)

Overnight Allowtostandforabout2hours. Removecathodesfromtheelectrolytes.Allowtodryover-

night.

Wellventilatedarea

Classtime:1lesson

Collectdata. Learnersanswerquestions8-12inwriting.

ScaleWorksheet

Classtime:lesson

Gothroughanswers. Memo

Practical preparation and tips• Youneed:carbon rods (youcouldget these fromdismantledbatteries), copperchloridesolution

electrolyteinabeaker,apowersupply(e.g.battery)andconnectiveleads.• Ifyoucannotgetcopperchloride,usebluewindowcleaner.• Tomeasureelectrodemass, youneedamass scale.Be sure tomeasureeach cathode's initial

massandtomarkeachoneclearly.Becarefulnottodislodgeanycopperfromthecathodesduringoraftertheexperiment.Allowtodrythoroughlybeforemeasuringthefinalmasses.

• ElectrolytecolourchangeisapoorpracticalindicatorofrateofelectrolysisofCuCl2(aq),sinceitisverydifficulttoseethedifferencebetweenmostcolourchangeswhichmightoccur.


Planning possibilitiesWatchthemovieintroductionabouttheplanningpossibilitiesoftheinvestigation.Youwanttoinvestigatehowvariousfactorsaffecttherateofelectrolysis.

1Suggestvariousfactorswhichmightaffecttherateofelectrolysis,whichyoucouldalterinthisinvestigation.Thesearepossibleindependentvariables.temperature of solution, concentration of solution, time left in solution, potential difference used, surface area of electrodes, distance between electrodes, volume of solution2Rate of electrolysisisthe dependentvariableforthisinvestigation.Givepossiblefocus questionsforthisinvestigation.Thesecanbewrittenintheform:Howdoes[independentvariable]affect[dependentvariable]?How does temperature of solution affect rate of electrolysis?


How does concentration of solution affect rate of electrolysis? How does time left in solution affect rate of electrolysis? How does potential difference used affect rate of electrolysis? How does surface area of electrodes affect rate of electrolysis? How does distance between electrodes affect rate of electrolysis? How does volume of solution affect rate of electrolysis?

3Completeforthreepossibleindicatorsofthedependentvariable(rateofelectrolysis):

Indicatorofelectrolysisrate IfIsee ,Iwoulddeducethattherateofelectrolysiswashigh

IfIsee ,Iwoulddeducethattherateofelectrolysiswaslow

colour of solution after a certain time

pale blue after e.g. 2,5 hours still dark blue after e.g. 2,5 hours

volume of chlorine gas formed in a certain time

much chlorine gas would be formed in e.g. 5 minutes.

little chlorine gas would be formed in e.g. 5 minutes.

mass of copper precipitated on electrode in a certain time

electrode would have gained a lot of mass, due to copper precipitation, in e.g. 2,5 hours.

electrode would have gained little mass, due to copper precipitation, in e.g. 2,5 hours.

Watchtherestofthemovie.

Focus question4Givethefocusquestionoftheinvestigationperformedonthemovie.Howdoespotential differenceaffectrate of electrolysis?

Treatments5Describethetreatments. Four electrolytic cells are used, with the following potential differences across their electrodes: A:1,5V B:3V C:4,5V D:6V

6Inwhichvariabledotheydifferfromoneanother?(Choose:)[Dependent/Independent]

Controlled variables7Listvariableswhichmustbethesamebetweenthedifferenttreatmentsforafairtest:temperature of solution, concentration of solution, time left in solution, surface area of electrodes, distance between electrodes, volume of solution

Tables8Tabulatetheresultseithershowninthemovie,or,preferably,fromyourownexperiment.Note: if learners use data from their own experiment, then their values will differ from those given here.Rawdatatable:Theeffectofpotentialdifferenceonrateofelectrolysis

Potential difference (V) Electrode mass (g)

Initial Final Change

1,5 6,50 6,90 0,40

3 6,50 7,33 0,83

4,5 6,51 7,93 1,42

6 6,57 8,17 1,60

Processeddatatable:Theeffectofpotentialdifferenceonrateofelectrolysis

Potential difference (V) Change in electrode mass due to copper deposition (g)

1,5 0,40

3 0,83

4,5 1,42

6 1,60



Check.Hasthelearner: Tickifdone:• givenasuitablegraphheading? • plottedtheindependentvariableonthex( )axis? • plottedtheindicatorofthedependentvariableonthey( )axis? • labelledeachaxisandgivenunitswhereappropriate? • accuratelyplotteddataanddrawnasmoothtrendline?


A higher potential difference causes the electrolytic reaction rate to be higher.

11Completeforashorterwayofwritingtheconclusion:Increasingpotential difference[increases/decreases/doesn'taffect]rate of electrolysis.

[independentvariable] [dependentvariable]


A higher potential difference is associated with a greater delivery of electrical energy to the circuit. In an electrolytic cell electrical energy is converted into chemical energy. A higher rate of delivery of electrical energy to the cell results in a higher rate of chemical reaction. Therefore the rate of electrolysis increases with an increased potential difference.

Check.Hasthelearner: Tickifdone:• completedthetableheadingssuitably? • headedthefirstcolumnswiththeindependentvariable? • givenunits,whereappropriate,intheheadings,notbody,ofthetable? • filledinalltreatmentdetailsinthefirstcolumn? • filledininitialandfinalmassreadings(processeddatatable) • correctlycalculatedandrecordedmasschangevalues(rawandprocesseddatatables)?


PROPERTIESOFFLOORWAXMEMO

Purpose• Learnersareguidedthroughthebasicaspectsofanexperimentalinvestigation.• Learnersplananadditionalinvestigationoftheirown.

Suggested teaching approach


Classtime:1lesson

Explainthenecessarytheoryaboutwaxandaboutthescien-tificmethod.

Showlearnersthemovieorperformtheinvestigationyourself. Discusstheinvestigation.Referto:variables,focusquestion,

hypothesis,results,conclusion,discussion.

PropertiesoffloorwaxmovieWorksheet(p.47-50)

Homework:lesson

Learnersanswerquestions1-16inwriting. Worksheet

Classtime:1lesson

Gothroughtheanswerstoquestions1-16withthelearners. Conductaclassdiscussiononfurtherinvestigationpossibili-

ties(questions17-22).Notethatanumberofpossibilitiescouldbecorrect,notonlytheonesuggestedhere.

MemoWorksheet

Homework:lesson

Learnerscompleteworksheetquestions17-22. Worksheet

Checklearners'work.Additionaltimeshouldbeallowedifyouwishtoperformtheexperimentinclass.

Practical preparation and tips• Youneed:acandle,paraffin,ameasuringcylinder,astove /hotplate,heat-resistant containers

(e.g.beakers)containerstostorethepolishin,cloths,planks,aprotractor,aslidingobject.• Ifyoucutastandardcandleinto1cmstrips,eachpiecewillhaveamassofapproximately4g.• Donotheattheparaffin.Addhot,moltencandlewaxtotheparaffinandmix.• Youwillprobablyfindquitealotofvariationinyourdata.Youwillalsoprobablyfinditdifficult to

decidewhentostoptiltingtheplank,especiallyforthehigherwaxcontentpolishes.Thisprovidesanexcellentopportunityforyoutodiscusslimitations,experimentalerror,variationindata,reliabilityandvalidity,withyourlearners.


Variables1Independentvariable.A polish's amount of candle wax (Cause.Whattheinvestigatormadedifferentbetweenthetreatments.)2Indicatorofthedependentvariable.Minimum angle causing sliding (Measurementofeffect.Whattheinvestigatormeasurestoshowtheinvestigationoutcome.)3Dependentvariable.Amount of friction the polish gives(Effect.Differentbetweenthetreatmentsbecausetheyhadbeentreateddifferentlyfromthestart.)4Controlledvariables(listatleastthree).(Mustbekeptthesamebetweentreatmentsforafairtest.)Thickness of layer of polish applied. Mass of sliding objects. Material type and degree of smoothness of planks. Temperature. Material type and degree of smoothness of sliding objects' bottom surfaces.

Focus question5Howdoesa polish's amount of candle waxaffectthe amount of friction the polish gives?

Theory6Whatisfriction?A force which resists motion.7Howcanfrictionbetweentwosurfacesbereduced?By making the object lighter, tilting the surface, or by making the surfaces smoother.


8Whydowewantpolishwithmorefriction?Friction reduces slipping. We want to shine and waterproof a floor with polish, but don't want this to make us slip.9Howdoescandlewaxdifferfromparaffin?-Candlewaxconsists of longer hydrocarbon chains.-whereasparaffinwaxconsists of shorter hydrocarbon chains.


Check.Hasthelearner: Tickifdone:• givenasuitablegraphheading? • plottedtheindependentvariableonthex( )axis? • plottedtheindicatorofthedependentvariableonthey( )axis? • labelledeachaxisandgivenunitswhereappropriate? • accuratelyplotteddatapointswithsmallcircleddots? • drawnasmoothtrendline?

11Itwouldbewrongtomakethisgraph'slinecuttheorigin(0,0).Why?The sliding object would not slide at 0 to the horizontal if the polish contained 0g candle wax.

Interpretation12Circlethecorrectoptiontoanalysethedata.

Amount of candle wax Minimum angle causing sliding Amount of friction polish gives

[more/less]friction

[more/less]friction

13Interprettheresultsinyourownwords.The more candle wax there is in the polish the more friction the polish gives.

Conclusion14Answerthefocusquestioninyourownwords.In learner's words. E.g. More candle wax, more friction.15Completeforashorterwayofwritingtheconclusion.Increasing a polish's amount of candle wax [increases / decreases / doesn'taffect] the amount of friction the polish gives.


The candle wax consists of longer-chained hydrocarbons. It is therefore more viscous than the paraffin, and so is more sticky, and therefore gives more friction.

a[higher/lower]slidingangleindicateshighwasfoundtocause

a[higher/lower]slidingangleindicateslowwasfoundtocause


Further investigation: Possible answerDesignanotherinvestigationofyourown,usingtheguidancegivenbelow.Itmusthaveadifferentfocusquestionfromthepreviousinvestigation.Note that there are other answers which could be considered correct too.

VariablesComplete/Givethe:17Independentvariable. Temperature Dependentvariable. Amount of friction polish gives.18Controlledvariables.(Mustbekeptthesamebetweentreatmentsforafairtest.)

Comparedtothepreviousinvestigation,giveonevariablewhich:amustbeconstantbetweentreatmentshere,butnotpreviously.

amount of candle wax compared to paraffinbmustnotbeconstantbetweentreatmentshere,butmustbepreviously

temperature (or whatever learner chose as their dependent variable here).

Focus questionComplete:19Howdoes temperature affect amount of friction polish gives? [independentvariable] [dependentvariable]

Method20Treatmentsdifferin: temperature Note: these values are only suggestions: any reasonable values are acceptable: A:10C C:50C B:25C D:80C

TableFillinheadingsandvaluesshowinghowyouwilltreatthetreatmentsdifferently.Includeunitsinheadingswhereappropriate.Leaveemptyspaceswhereyoucouldfilldatainaftertakingmeasurements.

The effect of floor polish's temperature on the amount of friction it gives

Temperature (C) Minimum angle causing sliding ( to horizontal)

A 10

B 25

C 50

D 80


GLOSSARY

Activation energy Theenergyrequiredtostartareaction.

Adsorption Aprocesswheresomethingbondstoasolid.

Alkali Solublebase.HasapHgreaterthan7.Tastesbitterandfeelssoapy.

Alkane Ahydrocarbonwhichhasonlysinglebonds.

Alkene Ahydrocarbonwithonedoublebondbetweentwoofitscarbonatoms.

Anode Anelectrodeatwhichoxidationoccurs.

Apparatus Equipment.

Battery Agroupofvoltaiccells.

Bleach Colour-remover.

Boiling point Temperatureatwhichasubstanceboils.Equalsitscondensationpoint.

Brine Saltwater.Dissociatedsodiumionsandchlorideionssurroundedbywater.

Catalyst Achemicalwhichspeedsupareactionbyloweringthereaction'sactivationenergy.Itisnotusedupbythereaction.

Cathode Anelectrodeatwhichreductionoccurs.

Chlorine Adensegreengaswhichisusefulasbleachanddisinfectant.

Chloralkaliindustry

Theindustrywhichmanufactureschlorineandsodiumhydroxidefromtheelectrolysisofsodiumchloride.

Closed (Chemicalsystem)Chemicalsdonoteitherenterorleavethesystem.

Conclusion Theanswertoaninvestigation'squestion,asshownbytheinvestigation'sdata.Mightbewrittenas:[dependentvariable][increases/decreases]withincreased[independentvariable].

Condensation Changingfromthegaseoustotheliquidphase.

Contact Process Theindustrialprocessbywhichsulfuricacid(H2SO4)isformedfromsulfur,oxygenandwater.

Controlled variable

Variablewhichiskeptthesamebetweentreatmentsforthewholeinvestigation.Cannotbetheindependentordependentvariables.

Crude oil Amixtureofhydrocarbonsofvariouslengths.Crudeoilismined.Lateritisseparatedintoitscomponents,e.g.bydistillation.

Data Measurements.

Dependent variable

Effect.Variablewhichbecomesdifferentbetweenthetreatmentsbecausetheyhadbeentreateddifferentlyfromthestart.

Desorption Aprocesswheresomethingseparatesfromasolid.

Detergent Aninorganicchemicalwhichisabletomakefatdissolveinwater.

Diaphragm Adividingmembrane.Madeofasbestosinthediaphragmcell.

Diesel Amixtureofhydrocarbonshaving12-18carbonatomspermolecule.Fuel.

Direct Proportion

Astheindependentvariableisincreased,thedependentvariableincreasesbythesamefactor.

Discussion Awrittendiscussionofthetrendsinthedata,andasuggestedexplanation,intermsofthebackgroundtheory.

Disinfectant Germkiller.

Dissociation Breakingapart.

Distillation Theprocessofseparatingamixtureduetocomponentsdifferentboilingpoints.

Distillation column

Alargecontainerwhichishottestatthebottom,andgetscoolerandcoolerwithheight.Usedfordistillation.

Dynamic equilibrium

Astatewhichcanbereachedwhenareversiblereactionoccursinaclosedsystem.Boththeforwardandreversereactionsoccuratthesamerateasoneanother.Theamountsofreactantsandproductsremainconstant.

Electrode Asiteatwhichtheredoxreactionsofanelectrochemicalcelloccur.Oftenarod.


Electrolysis Anon-spontaneouschemicalreactioninwhichacompoundisbrokendownintosimplercomponentsubstancesasanelectriccurrentpassesthroughit.

Electrolyte Anionicsolution.Suchasolutionisabletoconductelectricity.

Electrolytic cell Consistsofanexternalpowersource(e.g.battery),connectedtotwoelectrodesplacedinanelectrolyte.Electricalenergyisconvertedtochemicalenergy.

Endothermic Areactionwhichabsorbsmoreenergythanitreleases.

Exothermic Areactionwhichreleasesmoreenergythanitabsorbs.

Experimental investigation

Awayoffindingananswertoacause-effectquestion.Twoormoretreatmentsareused.Thesedifferonlyintheindependentvariableatthestart.Becauseofthistheymightgettodifferinthedependentvariable,whichismeasured.

Fischer-Trop-sch reaction

Thesecondstepinmakinghydrocarbons,e.g.petrol,fromcoal.Carbonmonoxideandhydrogenreacttoformwaterandhydrocarbons.

Focus question Aquestionwhichguideseverythingdoneinanexperimentalinvestigation.Mightbewrittenas:Howdoes[independentvariable]affect[dependentvariable]?

Gasification Thefirststepinmakinghydrocarbons,e.g.petrol,fromcoal.Carbondioxideandwatervapourreacttoformcarbonmonoxideandhydrogengas.

Haber Process Theindustrialprocessbywhichammonia(NH3)isformedfromN2andH2.

Halogen Veryreactivenon-metalsfoundnexttothenoblegasesontheperiodictable.

Hydrocarbon Anorganiccompoundconsistingonlyofbondedhydrogenandcarbonatoms.

Hydrocracking Hydrogenreactswithlong-chainedhydrocarbons,inthepresenceofacatalyst,tosplitthehydrocarbonintoshorterchains.

Hydrophilic 'Waterloving'.Attractedtowater.

Hydrophobic 'Waterfearing'.Repelledbywater.

Hypothesis Aguessedanswertothefocusquestion.Itmustbeinformedbybackgroundtheory.Itisthentestedbydoinganexperimentalinvestigation.

Independent variable Cause.Variabletheinvestigatormakesdifferentbetweenthetreatmentsfromthestart.

Indicator Aspecificwayofvarying,measuringorshowingupageneralvariable.

Inert Unreactive.

Inverse proportion

Astheindependentvariableisincreased,thedependentvariabledecreasesbythesamefactor.

Ionic bridge Anionicsolutionconnectingthetwohalfcellsinavoltaiccell.Necessaryforacompleteelectriccircuitandtopreventthebuild-upofionsineitherhalfcell.

Kerosene Amixtureofhydrocarbonswith9-14Catomspermolecule.Aeroplane(jet)fuel.

Le Chatelier's Principle

Whenasystemwhichisinequilibriumisdisturbed,itwillrespondinsuchawayastocounteractthedisturbance.

Lead acid battery

Acarbattery.Asecondarycellwithleadandleaddioxideelectrodesinasulfuricacidelectrolyte.

Liquid petroleum gas

(LPG)Amixtureofhydrocarbonshaving3-4carbonatomspermolecule.Soldasbottledgasforheatingandcooking.

Membrane Athinsheetorfilmwhichletsonlycertainionsthrough.

Mercury Apoisonoussilvermetalwhichisaliquidatroomtemperature.

Mercury cell Achlor-alkalicellwhichhasamercurycathode.

Method Stepsfollowedtofindananswertoafocusquestioninaninvestigation.

Mixture Consistsoftwoormorepuresubstancesnotchemicallybondedtooneanother.

Monomer Abuildingblockwhichisrepeatedmultipletimeswithinapolymer.

Nitrate AcompoundcontainingthecompoundionNO3-.Canbeabsorbedbyplants.

Nitrite AcompoundcontainingthecompoundionNO2-.Canbeabsorbedbyplants.

Nitrogen Anelementwhichisfoundinallproteins.ExistsintheelementalformasN2,whichforms78%ofair.PlantscannotabsorbN2.

Non-polar Havingnodistortioninelectrondistribution.


Polymer Along-chainedorganiccompoundmadeofmanymonomersbondedtogether.

Polymerisation Theprocessofformingapolymerfrommanyreactingmonomers.

PressureForceperarea.Ingases,pressureisrelatedtotherateatwhichparticleshitagainstthesidesoftheircontainer.Measuredinbars,atmospheres(atm),kiloPascals(kPa)andmillimetresofmercury(mmHg).

Primary cell Avoltaiccellwhichcannotberecharged.

Pure substance Asubstancewhichhasitsownchemicalandphysicalproperties.Maybeanelementoracompound.

Redox Akindofreactioninwhichelectronsaretransferred.

Reducing agent Achemicalwhichcausesanothertogetreducedwhileitisitselfoxidised.

Reduction Ahalfreactioninwhichonechemicalgainselectronsfromanotherchemical.

Reversible Areactionwhichcanoccurinboththeforwardandreversedirections.

Secondary cell Arechargeablecell.Voltaicduringdischarging.Electrolyticduringcharging.

Semi- permeable Allowssomesubstancesthroughbutblocksothers.

Soap Anorganicchemicalabletomakefatdissolveinwater.Madefromanimalfatandsodiumhydroxide.Moleculeshavehydrophilicheadsandhydrophobictails.

Sodium hydroxide Astrongalkali(solublebase).Canbeusedtomakesoap.Alsocalledcausticsoda.

Spontaneous Happensonitsown:withoutneedingtobeheated,forexample.

STP Standardtemperatureandpressure:273Kand101,3kPa.Areferencestate.

Temperature Ameasureofparticles'averagekineticenergy.MeasuredindegreesCelsius(C)orKelvin(K).

Treatments Groupswhicharetreateddifferentlyinoneway(theindependentvariable)atthestartofaninvestigation.Theremustalwaysbeatleasttwotreatmentsinanexperiment.

Uniform scale Ascalewithequallyspacedincreases,e.g.5kgincreaseeverycentimetre.

Unit Measurementscale,e.g.seconds(s).

Variables Propertieswhichmayvary(change)inquantity(howmuch)and/orquality(whatlike).

Viscosity Resistancetoflow

Voltaic cell Anelectrochemicalcellwhichconvertschemicaltoelectricalenergy.Aspontaneouschemi-calreactioncreatesapotentialdifference.

x-axis Horizontalaxis.

y-axis Verticalaxis.

Non-spontane-ous Doesnothappenonitsown.

Ostwald Process

Theindustrialprocessbywhichnitricacid(HNO3)isformedfromammonia(NH3)andoxygen(O2)

Oxidation Ahalfreactioninwhichonechemicalloseselectronstoanotherchemical.

Oxidising agent Achemicalwhichcausesanothertogetoxidisedwhileitisitselfreduced.

Petrol Amixtureofhydrocarbonshaving5-10carbonatomspermolecule.Fuel.

Polar Havingadistortioninelectrondistribution.Having+and-ends.


COPYRIGHTINFORMATION

Thisteacher'sguidewaswrittenunderaCreativeCommonsAttributionNon-CommercialShareAlikeLicense.Thismeansthatyouarefree:• to sharetocopy,distributeandtransmitthework.• to remixtoadaptthework.However,thefollowingconditionsapply:• Attribution.Youmustattributetheworkinthemannerspecifiedbytheauthororlicensor(butnot

inanywaythatsuggeststhattheyendorseyouoryouruseofthework).• Non-commercial.Youmaynotusethisworkforcommercialpurposes.• Share alike.Ifyoualter,transform,orbuilduponthiswork,youmaydistributetheresultingwork

onlyunderthesameorsimilarlicensetothisone.

Moreinformationonthiscopyrightrestrictionisavailablefrom:http://creativecommons.org/licenses/by-nc-sa/2.5/za/

Ifyouadaptanypartoftheteacher'sguide,pleaseincludethefollowinginyourversion:"AdaptedfromtheChemicalIndustriesResourcePack.2010.UniversityofCapeTown".

The learner informationsheets,posters,periodic table,animationsandmoviesareunderaCreativeCommonsAttributionNon-commercialNoDerivativeslicense.Thismeansthatyouarenotallowedtomakeanychangestoitinadditiontotherestrictionsdescribedabove.Formoreinformationaboutthiscopyrightlicense,pleasevisithttp://creativecommons.org/licenses/by-nc-nd/2.5/za/.

Thisresourcepackincludesregisteredtrademarksandlogoswhichareprotectedbylaw.YoumaynotreproducethetrademarkorlogoexceptwhensavingorprintingacopyofthematerialaspermittedbytheCopyrightNotice.Pleasedonot include the trademarksor logos insubsequentmodificationsofthematerial.

DISCLAIMER

The information included was obtained from public sources. At the time of writing we made everyeffort toensure theaccuracyof thecontent included.Wewouldappreciate it if youcouldbringanyinaccuraciestoourattention.

Wehavemadeeveryeffort toobtainpermissiontoreprintanddistributethecontent included in thisresourcepack fornon-commercialeducationalpurposes.Pleasecontactus ifyou feel thatwehaveincludedmaterialthatinfringesthecopyrightrestrictionsplaceduponit.

Thisresourcepackisintendedforuseinsecondaryschools.Wedonotacceptanyresponsibilityforincorrectorinappropriateuse.


THEPEOPLEBEHINDTHISRESOURCEPACK

• MrsRenToerien,DepartmentofChemicalEngineering,UniversityofCapeTown,wastheprojectcoordinator.

• AssociateProfessorJenniCase,DepartmentofChemicalEngineering,UniversityofCapeTown,supervisedtheprojectandgavevaluableinputintotheresourcepackasawhole.

• TheteamoftechnicalexpertsattheChemicalEngineeringDepartmentattheUniversityofCapeTownwhogavevaluableinputintothecontentsofthepack: ProfessorEricvanSteen AssociateProfessorMichaelClaeys MrStephenRoberts DrReinWeber

• TheteamoftechnicalexpertsatSasolwhogavevaluableinputintothecontentsofthepack: MrsMarsjaHall-Green,SasolGroupCorporateAffairs MrsCynthiaMalinga,SasolCorporateSocialInvestment MsKatherineGunningham,SasolTechnology DrTracyBromfield,SasolTechnology MrsSudikaHarkhuandDrHeinKruger,SasolInfrachem MrSibusisoLuvuno,BoitjhorisongResourceCentre DrRufusWesi,OsizweniResourceCentre

• DrAngelaStott,DepartmentofChemicalEngineering,UniversityofCapeTown,contributedtothe teacher'sguide,quizzes,laboratorymoviesandanimationsaspartofherpostdoctoralwork.• DrMargaret Blackie,Department ofChemical Engineering,University ofCape Town, developed

someoftheinvestigationsaspartofherpostdoctoralwork.• MrLanceJobwasresponsibleforcollatingtheinformationforthelearnersheetsandposters.• Rothkowasresponsiblefortheprofessionaldesignandlayoutoftheresourcepack.• DrElveraViljoenfromVera4Artdesignedall theanimationsandprovidedtechnical input intothe

contentsofthepack.• ManyPhysicalScienceteacherswhoparticipatedinthetrialsandworkshops,offeredhelp,shared

ideasandgaveencouragingcomments.

THESPONSORS

Thisprojectwouldnothavebeenpossiblewithoutthegenerousfinancialcontributionofoursponsors:

CONTACTINFORMATION

MrsRenToerienSchoolsProjectCoordinatorUniversityofCapeTown,DepartmentofChemicalEngineering,PrivateBag,Rondebosch,7701Tel:0216505527/2518Fax:0216505501Email:[email protected]

resource pack teacher's guide - vula : gateway : welcome · worksheets and quizzes are not...

Documents