chemistry, electrolysis (iva kubištová)
TRANSCRIPT
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Chemistry,Electrolysis(IvaKubištová)Time90minTopicexperimentalstudyofelectrolysisLessongoalsStudents(16–18)viaexperimentalmethodslearnprincipleofelectrolysis.Theywillimprovetheirexperimentalskills.Wholetaskfirst
Usually,inlabworksthestudentsgetonlyanexactlistofinstructions,whattodo.Inthislaboratoryworktheygetatfirstthemainquestion,thantheyhavetoexplainprincipleofit.Thequestionis:Whatisprincipleyourexperiment?Thestudentscanchooseeasytask(Taskone),midlyeasytask(Tasktwo)ordifficulttask(Taskthree).Theywillhaveamanualforexperimentsandafterexecutiongroupsneedfindtheirownandthencommonprincipleofit.
Taskone(SIMPLEELECTRICALCELL)Studentusemoldmakingice,zincgalvanizednails,CuwiresandLEDdiodeforconstructionsimpleelectricalcell.MANUALforSIMPLEELECTRICALCELL
Materials
• moldmakingicewithseparatespacesforwater• 7ormorezincgalvanizednails(about6cmlong)• 7ormoreCuwires(about6cmlong)• 5%solutionNaCl• LEDdiode
Procedure
1. Preparenailsandwiresasisinthepicturebelow.2. PourNaClsolution(5gofNaClin95mLofwater)intoshapesinmoldmakingice.3. Placenailsandwiresasisinpicturebelow.4. ConnectLEDdiodeasisinpicture.5. Explain,whatwashappen.
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moreonlink:
https://nationalmaglab.org/education/magnet-academy/watch-play/interactive/simple-electrical-cell
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Tasktwo(VOLTAGEINPOTATO)Studentusepotatoestocreatevoltage.MANUALforVOLTAGEINPOTATO
Materials
• afreshpotato• aselectrodetwononfatnails,Alligatorclips/Leads,9Vbattery• 20%solutionKI
Procedure
1. Takeapotatoandmakeholewithnonfatnails(about2,5cmdeep).2. PourKIsolution(20gofKIin80mLofwater)intoholes.3. PlacetwoelectrodesandconnectAlligatorclips/Leadsand9Vbattery.4. Disconnectitandcutpotatoasinthepictureafter15minutes.5. Surroundingsofoneelectrodeisblue.6. Putphenolphthaleinnearsecondelectrode.7. Explain,whatwashappeninpotatoafterconnectingandafter15minutes?
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Taskthree(TINMAN)Electrolysisof tin(II) chloridegrowabeautiful “tin-man”crystal treeby runninganelectric currentthroughasolutionoftin(II)chloride.MANUALforTINMAN
Materials
• Tin(II)chloride,SnCl2,5g• Water,distilledordeionized,100mL• Petridish,Beaker250-mL• Supportstand,funnelandfilterflask,filterpaper• Battery,9-V,Batterycapwithalligatorclip,leads• Paperclips,small,2
Procedure
1. AttachtwopapersclipstooppositesidesofacleanglassPetridish.Besurethelongendsofthepaperclipsareontheinsideofthedish,nearlytouchingthebottom.
2. Dissolve5goftin(II)chloridein100mLofdistilledordeionizedwaterina250-mLbeaker. 3. Filterthetin(II)chloridesolutionandallowtheliquidtodripintothePetridish. 4. CollectenoughliquidtojustcoverthebottomofthePetridish.Attachthealligatorclipsfromthe
9-Vbatterycaptoeachpaperclip. 5. Hookthebatterycaptothe9-Vbatteryandobservethechangesattheanodeandthecathode.A
milkywhiteprecipitateoftin(IV)chlorideappearsattheanodeandmetallictin(0)crystalsformatthecathode.
6. Allowthecurrenttorunforapproximatelyoneminutetoseethecontinuedgrowth.Thetin(0)crystalsformfeatherlikeprojectionsandgrowacrossthedish.
7. Explain,whatwashappen.
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Allprocedure(andmore)youcanseeonlink:https://www.flinnsci.com/api/library/Download/2a738661a20c47b6a1d9f28fc30735be
CunclusionofwholelessonAllstudentareworkingingroups,andcomparingtheirresults.Theteacherhelpstofinishtheformulas.Notesforteachers:
Teachercanusedtheseexperimentsfornexttermsornames:wetcell,voltaic(orgalvanic)electricalcell,electrochemistry,LuigiGalvani,AlessandroVolta,battery,electrolyte,redoxprocesses(oxidation,reduction), potential (voltage) difference, circuit, flowof electrons, flowof ions, electrode (anode,cathode),conductionofelectricity(polarization),ioniccurrent
Sourceofpicturesauthor