Download Chemistry Club Demos - 10-8-15

ChemistryClubDemos
CAUTION:
Allofthefollowingexperimentsarepotentiallyhazardous,andmayonlybeperformedbytrainedindividualswhile
wearingproperattire(longpants,closed-toe/heelshoes)andfullPersonalProtectiveEquipment(PPE).MinimumPPEis
anappropriatelabcoat,safetyglassesorsplash-proofgoggles,andnitrilegloves. AdditionalPPEmightberequired,
dependingonthehazardsofthedemonstration. ThisadditionalPPEwillbedetailedinthedemowrite-up.
Contents
BanginaCan.............................................................................................................................................................................2
BlueBottle.................................................................................................................................................................................3
BorateFlame.............................................................................................................................................................................4
BottleRockets...........................................................................................................................................................................5
ElephantToothpaste.................................................................................................................................................................6
EthanolCannon.........................................................................................................................................................................7
ExplodingBalloons....................................................................................................................................................................8
FiveColorsfromOneSolution...................................................................................................................................................9
GenieinaBottle......................................................................................................................................................................10
GrowlingGummyBear.........................................................................................................................................................11
IndicatorRainbow...................................................................................................................................................................12
InstantCoca-Cola.....................................................................................................................................................................13
InstantFire...............................................................................................................................................................................14
LiquidNitrogen........................................................................................................................................................................15
Luminol....................................................................................................................................................................................17
Magnesium/DryIce..............................................................................................................................................................18
SilverMirrorinaFlask.............................................................................................................................................................19
TrafficLightReaction...............................................................................................................................................................21
VinegarCannon.......................................................................................................................................................................22
1
BanginaCan
RequiredTraining
UCLabSafetyFundamentals
RequiredPPE
Flame-resistantlabcoat,safetyglasses/goggles,
hearingprotection,nitrilegloves
Equipment
Steelcanwithmetallid(shipping/1gallonpaintcan)
Drill/punchandpliersforpreparingcan
BBQ-stylebutanelighter(≥6”long)
Maskingtape
Chemicals
Methane(CH4)orhydrogen(H2),withregulatorand
tubinginstalled.
Procedure:
1.)Topreparethecan,firstpunchordrillasmall(1/8-1/4”)holeinthecenterofthebottomofthecan;thiswillactas
thegasoutletandpilotlight.Thencut/drilltwomedium(1/2”)holesinthesideofthecan,roughly1”fromtherim
oftheopeningandoppositeeachother;theseactasair-intakevents. Coverallthreeholeswithadhesivetapesuch
thattheycanbeopenedquickly. Finally,useplierstocompressthepress-fitringaroundthecircumferenceoflid,
suchthatitfitsverylooselyonthecan–thelidshouldfalloffwhenthecanisinverted.
2.)Tofillthecanwithafuelgas,holdthelidslightlyoffsetfromthecanandinsertthehosebarbortheendofthetube
attachedtotheregulatoronacylinderorothersupplyofflammablegas(CH4 orH2).Untapethesmallpilotholeon
thebottomofthecan,andproceedtofillthecan(~30secondswitha5psiregulator). Whenthecanisfilled,retape
thepilothole,removethehosebarbortube,andpressthelidlooselyontothecantotrapthegas.
3.)Immediatelyplacethecanonatable(farawayfromthegascylinder)withthebottomofthecanandpilothole
facingup.Ensureyouarewearinghearingprotectionandthattheaudiencehasbeenwarnedtocovertheirears
beforeproceeding.Removethetapefromthepilotandventholes,andusethelightertoignitethegasescaping
fromthepilothole,steppingbackonceitislit. Therewillbeasmallflamevisiblefromthepilothole,thoughitwill
beverydifficulttoseeifthefuelgasishydrogen(dimmingthelightswillbehelpfultoseethepilotflame). Oncethe
upperexplosivelimitisreached,themixtureofgasesinthecanwillignitewithaloudbang,sendingthecanflying
upwards(~10-30feet).
Clean-up: Nonerequired.
Hazards:Theexplosioninthecanproducesheat,fire,andaloudnoise,andthecanislaunchedupwardswith
considerableforce.Hazardsincludethermalburnsfromthefireorthecanimmediatelyaftertheexplosion,hearing
damagefromtheexplosion,orphysicalinjuryfrombeinghitwiththecan.
Principle: Thegasinthecanislighterthanair,andescapesfromtheholeinthetopoftheinvertedcan,whileairis
pulledintothecanthroughtheholesinthesidestoequalizethepressure. Lightingthestreamofgasthroughthetop
createsapilotlightthanremainslituntilthemixtureinsidereachesaparticularconcentrationknownastheupper
explosivelimit. Atthispoint,theflamewillflashbackthroughtheholeandignitetheentiremixtureatonce,forming
hotgaseousH2O(andCO2 ifusingmethane)thatforcesthecanupwardswhenitseparatesfromthelid.Theupper
explosivelimitsinairareroughly15%forCH4 and75%forH2 byvolume.
Notes: Itmaytakeupto1-2minutesforthemixturetoignite,dependingonthefuelgasandthesizeoftheholes.If
theignitiondoesnotoccur,donotplaceyourhandoverthecanifyouattempttorelightthepilot,astheflamemaystill
belitandthemixturemayigniteatanymoment. Intheeventofafailedignition,leavethecanundisturbedforatleast
5minutesbeforeremovingthelidwellawayfromanyignitionsources.
2
BlueBottle
RequiredTraining
UCLabSafetyFundamentals
Equipment
500-mLFlorence/Erlenmeyerflask(orlarger)
Rubberstoppertofitflask
RequiredPPE
Labcoat,safetyglasses/goggles,nitrilegloves
Chemicals
Dextrose(D-glucose,C6H12O6)
Potassiumhydroxide(KOH)
MethyleneBlue(M.B.),1%solution
Procedure:
1.)Add300mLwater,8gKOH,and10gdextrosetotheflask,swirlingthesolutionuntileverythinghasdissolved.2.)
Add5-6dropsoftheM.B.indicatorsolution,swirlingagaintomix. Thesolutionwillinitiallyturnblue,butaftera
fewmomentsitwillbecomecolorless.
3.)Toperformthedemo,stoppertheflaskandshakethesolutionvigorously,makingsuretoholdthestopperinplace
withonehand.Thesolutionwillturnblueaftersufficientshaking. Afterthesolutionhasturnedblue,stopshaking
andletthesolutionrestfor~10seconds,atwhichpointitwillbecomecolorlessagain.
4.)Thisreactioncanberepeatedseveraltimes(occasionallyupto8)beforethesolutiondecomposesandturnscloudy.
Clean-up: Thewastesolutionmayberinseddownthesinkwithcopiousamountsofwater.
Hazards:KOHisastrongbaseanditssolutionsarehighlycorrosive,causingimmediatechemicalburnsoncontact.
Principle: Thisdemonstrationinvolvesareversibleoxidation-reductionreactionbetweenM.B.,oxygen(O2),anda
reducingsugar.M.B.isacommonredoxindicatorthatisblueinoxidizingenvironmentsandcolorlessinreducing
environments. Whentheflaskisshaken,atmosphericO2 isdissolvedinthesolutionandoxidizestheM.B.toitsblue
form. Dextroseisareducingsugar,andinalkalinesolutionitisconvertedtoanenolatewhichreducestheM.B.backto
itscolorlessform;thedextroseisultimatelyoxidizedintoarabinonicacidandformateanions(Scheme1,seereference).
Shakingtheflaskagainintroducesmoreoxygen,whichrepeatsthecycleuntilnodextroseremains.
Notes:Thesolutionwillremainblueatthegas-liquidinterface,asthereissufficientoxygentokeeptheM.B.initsblue
form. Thetransitiontimefrombluetocolorlesswillincreasewithsuccessivecycles;also,theconversioncanbe
drasticallyslowedbyhalvingtheconcentrationsofthereagents. Alternately,stirring/swirlingtheflaskinsteadof
shakingitwillcausemuchmorerapidcolorchanges,aslessoxygenisdissolvedandlessoftheM.B.isoxidized.
References:Andersenetal.J.Chem.Educ.2012,89,1425-1431. DOI: 10.1021/ed200511d.
3
BorateFlame
RequiredTraining
UCLabSafetyFundamentals
RequiredPPE
Flame-resistantlabcoat,safetyglasses/goggles,
nitrilegloves
Equipment
1-LErlenmeyerflaskwithboilingchips
RubberstopperfittedwithanS-shapedglasstube
Hotplatewithclampforflask
BBQ-stylebutanelighter(≥6”long)
Chemicals
Boricacid(B(OH)3)
Methanol(CH3OH)
Sulfuricacid(H2SO4),18M
Procedure:
1.)Add2-3mLofH2SO4 to150mLofCH3OHinthe1-LErlenmeyerflask.2.)
Add30gofB(OH)3 tothemixtureandstiruntilallsolidshavedissolved.
3.)Addafewboilingchipstotheflaskandplaceitintheclamponthehotplate. Puttherubberstopperwiththe‘S’-
shapedtubeintheneckoftheflask,andheatthemixturetoavigorousboil. Thismaytake5-10minutes,and
shouldbestartedslightlybeforethedemoistobeperformed.
4.)Ignitethevaporatthetopofthe‘S’-shapedtubewiththelighter.Ifthevapordoesnotignite,increasetheheat
fromthehotplate. Ensurethemixtureisboilingrapidlyenoughtomaintainaflame~4-6”inheight,butnotso
rapidlythatitboilsover.
5.) Whenfinished,turnoffthehotplate.Youmayeitherblowouttheflameorsimplywaituntilthemixturehascooled
sufficiently,astheflamewilldiminishandthenself-extinguishastheboilingsubsides.
Clean-up:Theflaskshouldremainclampedtothehotplatetominimizethechanceofspillingmethanolaroundany
ignitionsources. Onceeverythinghascooledtoroomtemperature,themixtureshouldbesavedforfutureuseby
replacingthe‘S’-shapedtubewithasolidrubberstopper.
Hazards:Sulfuricacidisstronglyoxidizingandcorrosive,andwillcauseimmediatechemicalburnsoncontact.
Methanolistoxicandhighlyflammable.Keepallsolutionsawayfromignitionsourcesuntilthedemoisperformed.
Principle: B(OH)3 willreactwithCH3OHinthepresenceofadehydratingagent(H2SO4)toformtrimethylborate
(B(OCH3)3)andH2O.Thisborateesterisvolatile(b.p.=68°C)andburnswiththegreenflamecharacteristicofallboron
compounds. Thecolorisduetobroadbandemissionsinthegreenregionofthespectrumfromvariousmolecular
speciesastheyrelaxfromexcitedelectronicstatesbacktotheirgroundstates.
Notes:Afreshly-preparedsolutionmaybeaddedtotheflaskwheneverthevolumeofthesolutionbecomestoolowto
performthedemonstration(<50mL).Donotheattheflaskwithanopenflame,asthismaycausethemixturetobump
andboiloutoftheflask,creatingafast-spreadingmethanolfire. PerformingthedemonstrationwithouttheS-shaped
glasstubeisnotrecommended;whilethisproducesalargerflame,itisnotself-extinguishingandthereisamuch
greaterriskofthesolutionboilingoverifitbumps.
4
BottleRockets
RequiredTraining
UCLabSafetyFundamentals
RequiredPPE
Flame-resistantlabcoat,safetyglasses/goggles,
hearingprotection,nitrilegloves
Equipment
Clean,dry1-or2-Lsodabottleswithcaps
Launchpad(small/mediumironringsonsteellabstand)
BBQ-stylebutanelighter(≥6”long)
Chemicals
Methanol(CH3OH)
Oxygen(O2),withregulatorandtubinginstalled
Procedure:
1.)Rinseanddrythesodabottlesifnecessary.
2.)Fillthebottleswithoxygengasfromthecylinderinthedispensary.Holdthebottleovertheoutletoftheregulator
(setto~5psi)for~30seconds.
3.)Quicklyadd~5mLofmethanoltothebottleandscrewthecapontightly. Shaketheclosedbottletodispersethe
methanol. Thedemocanbeperformedimmediately,buttheeffectwillbegreaterifthebottleisallowedtositat
roomtemperatureforatleast20minutes. Donotstorepreparedbottlerocketsformorethan24hours,andkeep
themoutofdirectsunlightandawayfromheatorignitionsources.
4.)Beforethedemo,quicklyloosenthecapandallowanyexcessmethanoltodrainout,andthenretightenthecap. Do
thisawayfromanyignitionsources.
5.)Tomountthebottleonthelaunchpad,simplyplacethebottlecapsidedowninoneoftheironrings.
6.)Ensureyouarewearinghearingprotectionandthattheaudiencehasbeenwarnedtocovertheirearsbefore
proceeding.Unscrewthecapfromthebottleandholdtheflamefromthebutanelighterneartheopening.Keep
yourhandtothesideofthebottlerocket,andneverplaceanythingdirectlyaboveorbelowthebottle. Thebottle
rocketshouldneverbepointedtowardsotherperformersortheaudience. Onceignited,therewillbealoudnoise
andthebottlerocketwillquicklylaunch~10-100feetintotheair,largelydependingonambienttemperature.
Clean-up: Nonerequired,exceptforretrievingallbottlesandcapsforrecycling.
Hazards: Methanolistoxicandhighlyflammable;itshouldbekeptawayfromheatorignitionsources,especiallywhen
inanoxygen-richenvironmentsuchasapreparedbottlerocket. Methanolburnswithanalmostinvisibleblueflame,
whichisextremelydifficulttoseeinbrightlight.Launchingtherocketsproducesheat,fireandaloudnoise,andthe
bottleislaunchedupwardswithgreatforce. Hazardsincludethermalburnsfromthefire,hearingdamagefromthe
explosion,orphysicalinjuryfrombeinghitbythelaunchingbottle.
Principle: Thecombustionofmethanolinapureoxygenenvironmentproducescarbondioxide(CO2),watervapor,and
heat.Thesehotgasesquicklyexpandandexitthebottlethroughtheneck,creatingthrustthatpropelstherocket
upwards.
Notes: Methanolhasaflashpointof11°C(52°F),andthevaporpressureincreasesdramaticallywithincreasing
temperature. Ifthisdemoistobeperformedduringthewintermonths,thebottlerocketsneedtobekeptabovethis
temperatureinordertoignite,andkeptcloseto20°C(68°F)inorderfortheretobeenoughfuelinthemixturetogeta
decentlaunch. Thiscanbeachievedbyplacingroom-temperaturebottlesinaninsulatedbag,onlyremovingthemone
atatimeastheyarelaunched. Ifitissunnyoutside,thebottlesmaybewarmedbyplacingthemindirectsunlightfor
nolongerthan5-10minutes,oruntiltheyarejustbarelywarmtothetouch.Undernocircumstancesshouldthebottle
rocketsbeheatedbeyondthispoint,asthiscouldcausethemtoburstorigniteinanuncontrolledfashion. 2-Lbottles
willbecomeslightlywarpedfromtheheatofthelaunch,andshouldnotbereused;smaller1-Lbottlesholdup
significantlybetterandcanusuallybereused2-3times.
5
ElephantToothpaste
RequiredTraining
UCLabSafetyFundamentals
Equipment
1-Lglassgraduatedcylinder
Clearplastictub
RequiredPPE
Labcoat,safetyglasses/goggles,nitrilegloves
Chemicals
Hydrogenperoxide(H2O2),30%solution
Potassiumiodide(KI),solidpowderorsat.solution
Dishsoap
Foodcoloring(optional)
Procedure:
1.)Placetheclearplastictubontheground,andthenplacethegraduatedcylinderinmiddleofthetub.
2.)Pour~50mLH2O2 intothegraduatedcylinder.
3.)Pour~3mLofdishsoapintothecylinderandagitateslightlytomix.
4.)(optional)Runafewdropsoffoodcoloringdownthesidesofthecylinderforastripingeffect.
5.)Therearetwomethodsforperformingthisdemonstration:
Method1)Quicklypour~10mLofthepotassiumiodidesolutionintothecylinderandstepback,asalargevolume
ofsoapsudswillveryquicklyeruptfromthetopofthecylinderandlandintheplastictub.
Method2)Add0.5gofsolidKIpowdertothecylinderandstepback. Asthesolidmustdissolveanddiffusethrough
thesolution,thisreactionismuchslowerandproducesastreamoffoamfromthecylinderthatmaycontinue
foruptoaminute.
6.)Thisreactionproducesasignificantquantityofheat,andthegraduatedcylinderwillbehottothetouch. Allowitto
coolsufficientlybeforemovingthedemonstration.
Clean-up: Onceeverythinghascooledtoroomtemperature,allwastecanbesafelyrinseddownthedrain.
Hazards: 30%H2O2 iscorrosiveandstronglyoxidizing,causingimmediatechemicalburnsoncontactwithskin. Always
wearnitrilegloveswhenpreparing,performing,orcleaningupthisdemo.Furthermore,thecatalyticdecompositionof
H2O2 isstronglyexothermic,andthegraduatedcylindermaybecomewarmenoughtocausethermalburnsduringthe
demonstration.
Principle: ThisdemonstrationinvolvesthecatalyticdecompositionofH2O2 intowater(H2O)andoxygengas(O2(g)). The
overallreactionis:
2H2O2(aq)-->2H2O(l)+O2(g)
Thisreactionisslow,butmaybecatalyzedbytheiodideion(I-).Oneproposedmechanismforthisreactionis:
H2O2(aq)+I-(aq)-->OI-(aq)+H2O(l)
H2O2(aq)+OI-(aq)-->I-(aq)+H2O(l)+O2(g)
Asignificantquantityofheatisalsogenerated(ΔrH°=−196kJ/mol),whichvaporizessomeoftheH2Ointosteam. The
soapcatchestheevolvedsteamandoxygen,formingmanysmallbubblesthatcoalesceintoafoam.
Notes: Moreisgoingoninsolutionthanjustthereactionsgiveninthemechanismlistedabove. UpontheadditionofKI,
thesolutionbecomesared-browncolorthatslowlyclears,evidencefortheformationandsubsequentconsumption
-
-
ofiodine(I2)andthetriiodide(I3 )anionsthatformuponreactionwithexcessI. Researchonthereactionmechanisms
andkineticsofthissystemisstillongoing.ThisdemonstrationisnearlyidenticaltoGenieinaBottle,whichdoesnotuse
soaptocatchtheevolvedgases.
6
EthanolCannon
RequiredTraining
UCLabSafetyFundamentals
RequiredPPE
Flame-resistantlabcoat,safetyglasses/goggles,
nitrilegloves
Equipment
EthanolCannonAssembly–six250-mLNalgenebottles
withnailsinsertedhalfwayintothesides
Corkstofitbottles
Teslacoil
Chemicals
Ethanol(EtOH),≥95%solution
Procedure:
1.) Pour~2mLofEtOHintoeachbottle,thencorkthebottlesandwait~2minutesfortheEtOHtoevaporate.
2.)Ensurethatthebottlesarenotpointedattheaudience,otherperformers,oranythingfragile(i.e.lightfixtures).
3.)TurnontheTeslacoilandtouchthetiptooneofthenails.Asparkshouldjumpthegapbetweenthenailsinsidethe
bottles,causingtheethanolvaportoigniteandthecorkstoshootoutofthebottles.
4.)ThedemocanberepeatedseveraltimeswithoutaddinganymoreEtOH,solongasthebottlesareflushedwithair
beforetheyarere-corked.
Clean-up: ExcessEtOHcanberinseddownthedrain,orleftinthebottlesuntilitevaporates.Besuretoretrieveallof
thelaunchedcorks.
Hazards:EtOHishighlyflammableandshouldbekeptawayfromignitionsources.Thecorkscanfly30-40feetwith
considerableforce,andadirectimpactcouldresultinphysicalinjury. TheTeslacoilproducesahigh-voltage,low-
amperageelectricaldischarge,andcarelesshandlingcanresultinapainfulelectricalshock.
Principle: TheTeslacoilcausesasparktojumpbetweenthenailsinthebottle,andthissparksuppliesenoughenergyto
initiatethecombustionofEtOH,creatingCO2 (g)andH2O(g).Thesegasescannotescapetheclosedvessel,sothe
pressureincreasesuntilthecorkisejected. Whileessentiallyalloftheoxygeninthebottlesisconsumes,asignificant
amountoftheEtOHremains,suchthatrefreshingtheairinthebottlesallowsforrepetitionofthedemonstration.
Notes: Makesurethereisnorustorcorrosiononthenails,andthatthetipsarespacedjustfarenoughapartthatthere
isavisiblesparkbetweenthemwhentheTeslacoilistouchedtoonenail. TheexplosivelimitsofEtOHvaporinairare
~3-20%byvolume,andtheflashpointis12.8°C(55°F). Theambienttemperaturemustbeabovetheflashpointforthe
cannontoignite,andthestrengthofthecombustionincreaseswithtemperature.
7
ExplodingBalloons
RequiredTraining
UCLabSafetyFundamentals
RequiredPPE
Flame-resistantlabcoat,safetyglasses/goggles,
hearingprotection,nitrilegloves
Equipment
Latexballoons
String
Weightedobjectstoanchorballoons
Candleon1-meterstick/pole
Chemicals
Helium(He),withregulatorandtubinginstalled
Hydrogen(H2),withregulatorandtubinginstalled
Oxygen(O2),withregulatorandtubinginstalled
Methane(CH4)(optional),withregulatorandtubing
installed
Procedure:
1.)Filltheballoonsfromthegascylindersinthedispensarywithappropriatemixturesofgases. Thisincludespure
helium,purehydrogenormethane,anda2:1mixtureofhydrogenandoxygen.NevermakeamixedCH4/O2 balloon
–thepoweroutputistoolarge(~3timesthatofaH2/O2 balloon),makingitunsafeforperformanceevenwhen
outdoors.Tietheballoonsoffandattachthestringstoboththeballoonsandtheweightedanchors. Labelthetop
ofeachballoonwithasharpiemarkersotheperformersknowwhichgas/mixtureisinside.
2.) Positiontheballoonsandtheiranchorsatleast10feetfromtheaudience.Alternatively,tietheballoonsdirectlyto
stationary,non-flammableobjectsthatareasimilardistancefromtheaudience.
3.)Ensureyouarewearinghearingprotectionandthattheaudiencehasbeenwarnedtocovertheirearsbefore
proceeding.Furthermore,ifthereisanywind,makesureyouarestandingupwindoftheballoon.Lightthecandle
ontheendofthepole,andplaceitnexttotheballoon.Itwillpop(helium),ignite(H2 orCH4),orexplode(H2/O2)
afterafewseconds.
Clean-up:Makesuretocleanupallofthepieceslatexandstring.
Hazards:TheH2,CH4,andH2/O2 balloonsproduceheat,fire,andaloudnoisewhenignited.Hazardsincludethermal
burnsfromthefireandhearingdamagefromtheexplosion.WhentransportingH2,CH4,andH2/O2 balloons,takecare
tokeepthemawayfromignitionsourcesandeachother,ifmovingmultipleballoons. Theyshouldneverbegrouped
intoabagfortransportation,asthebuild-upofstaticelectricitycouldcausethemtoignite. NeverbringaH2/O2 balloon
intoaconfinedspacesuchasanelevator,asanaccidentalexplosioncouldcausedeafnessandgreatpersonalinjury.
H2/O2 balloonscannotbetransportedinvehiclesforlegalreasons,andmayonlybeusedforoutdoordemonstrationson
campus.
Principle: Theheliumballoondoesn’texplodebecauseheliumisaninertgaseouselement.Theflammablegasesinthe
balloonscombustintowatervapor(andCO2 withCH4 fuel)whenignited. TheCH4 balloonreleasesthemostenergy,but
ithasthelowestpowerbecausethecombustionproceedsslowly. TheH2 balloonreleasesapproximately1/3rd ofthe
energy,butitburnsmuchfasterandthereforeproducesmuchmorepower. TheH2/O2 balloonreleasesthesame
energyastheH2 balloon,butwithsignificantlymorepower(creatingashockwave);asthegasdoesnotneedtodiffuse
intotheairtomixwithoxygen,thecombustionoccurswithmuchgreaterspeed.
Notes: WhenmakingmixedH2/O2 balloons,firstfilltheballoononethirdwithoxygen,andthenfillittherestoftheway
withhydrogen,stoppingshortlyafteritbecomespositivelybuoyant. Thisisstillaveryoxygen-richmixture,butitlimits
theconcussiveforceoftheexplosion. Themixedballoonsshouldnotexceed6-8”indiameter,andmustneverbe
ignitedindoors.WhenignitingCH4 balloons,occasionallytheywillpopandblowoutthecandlewithoutigniting. Itis
helpfultoholdthecandletoonesideoftheballoon,andtokeepitinplaceaftertheballoonhaspoppedtoensure
ignition.
8
FiveColorsfromOneSolution
RequiredTraining
UCLabSafetyFundamentals
Equipment
Five250-mLbeakers
Disposablepipettes
RequiredPPE
Labcoat,safetyglasses/goggles,nitrilegloves
Chemicals
Phenolphthaleininethanolsolution
Sodiumcarbonate(Na2CO3),5%solution
Iron(III)chloride(FeCl3),50%solution
Ammoniumthiocyanate(NH4SCN),30%solution
Potassiumferrocyanide(K4[Fe(CN)6]),5%solution
Procedure:
1.)Topreparethisdemonstration,addthefollowingtofiveseparatebeakers:
#1:100mLwaterand1mLphenolphthaleinsolution
#2: 10dropsofNa2CO3 solution
#3: 7dropsofFeCl3 solution
#4: 1mLofNH4SCNsolution
#5: 1mLofK4[Fe(CN)6]solution
2.) Pourthecontentsofbeaker#1into#2,thenfrom#2into#3,thenfrom#3into#4,andfinallyfrom#4into#5.
Therewillbeadistinctcolorchangewitheachsuccessivestep;#1iscolorless,#2isfuchsia(basicphenolphthalein),
#3isyellow(acidicFe3+(aq)),#4isred(Fe(SCN)2+ species),and#5isdeepblue(Prussianblue).
Clean-up: Thecontentsofbeaker#5canbedilutedwithwaterandrinseddownthedrain.
Hazards:Ethanolsolutionsareflammable,andshouldbekeptawayfromignitionsources.SolutionsofFeCl3 are
corrosivetometals. Phenolphthalein,FeCl3,andNH4SCNaretoxicifswallowed,andphenolphthaleinisapotential
carcinogenandreproductivehazard. ThePrussianbluepresentinbeaker#5willstainskinandclothing.
Principle: Thisdemonstrationusesanindicatorandseveraldifferentreactionproductstoproducefivedifferentcolors
fromasinglesolution. Theindicatorphenolphthaleiniscolorlessinneutralsolution(beaker#1),butturnsfuchsiainthe
presenceofthebasicNa2CO3 solutioninthesecondbeaker.InthethirdbeakertheH3O+ ionsproducedbythehydrolysis
oftheiron(III)saltbindtheOH- ionsfromtheNa2CO3 solution,leadingtodecolorizationofthephenolphthalein;atthe
sametimethesolutionturnsyellowduetothepresenceofthehydrolyzediron(III)species:
[Fe(H2O)6]3++ H2O→[Fe(H2O)5(OH)]2++ H3O+
[Fe(H2O)5(OH)]2++H2O→[Fe(H2O)4(OH)2]++H3O+etc
Inthefourthbeakeriron(III)saltsformdeepredcomplexessuchas[Fe(SCN)(H2O)5]2+ withtheSCN- ions.Theextreme
stabilityofcolloidalPrussianblue(KFeIII[FeII(CN)6])dominatesinthefifthbeaker,sothatthedeepbluecolorbringsthe
seriestoaclose.Deviationsfromthegivenconcentrationscanleadtoslightdifferencesintheeffectsduetothe
formationofprecipitatesormixedcolors.
Notes: Ensurethethiocyanatesolutionisfresh(<3weeksold),asitslowlydecomposesandgivesmuddybrown
precipitatesinsteadofthedesireddeepredcolor.
9
GenieinaBottle
RequiredTraining
UCLabSafetyFundamentals
Equipment
2-LFlorenceorround-bottomflaskandcorkring
RequiredPPE
Labcoat,safetyglasses/goggles,nitrilegloves
Chemicals
Potassiumiodide(KI)
Hydrogenperoxide(H2O2),30%solution
Procedure:
1.) Placetheflaskonthecorkringonthegroundatleast10feetfromtheaudience.
2.) Pour~50mLofH2O2 intoflask. Theliquidshouldcomeuptoroughlythelevelofthetopofthecorkring.
2.)Add~0.5gofsolidKIpowderintotheflaskandquicklymoveback. Thereactionbeginsslowly,butacceleratesas
moreKIdissolvesinthesolution. Aplumeofsteamwillbereleasedfromthetopoftheflaskasthecontentsboil.
Allowtheflasktocoolsufficientlybeforemovingthedemonstration.
Clean-up: Onceeverythinghascooledcompletely,thesolutioncanberinseddownthedrainwithwater. Makesureto
rinsetheflaskthoroughlywithdistilledwatertopreventprematurereactionsinfuturedemonstrations.
Hazards: 30%H2O2 iscorrosiveandstronglyoxidizing,causingimmediatechemicalburnsoncontactwithskin.Always
wearnitrilegloveswhenpreparing,performing,orcleaningupthisdemo. Furthermore,thecatalyticdecompositionof
H2O2 isstronglyexothermic,andtheflaskmaybecomewarmenoughtocausethermalburnsduringthedemonstration.
Principle: ThisdemonstrationinvolvesthecatalyticdecompositionofH2O2 intowater(H2O)andoxygengas(O2(g)). The
overallreactionis:
2H2O2(aq)-->2H2O(l)+O2(g)
Thisreactionisslow,butmaybecatalyzedbytheiodideion(I-).Oneproposedmechanismforthisreactionis:
H2O2(aq)+I-(aq)-->OI-(aq)+H2O(l)
H2O2(aq)+OI-(aq)-->I-(aq)+H2O(l)+O2(g)
Asignificantquantityofheatisalsogenerated(ΔrH°=−196kJ/mol),whichvaporizessomeoftheH2Ointosteam. The
steamproducesanice“smoke”effect.
Notes: Moreisgoingoninsolutionthanjustthereactionsgiveninthemechanismlistedabove. UpontheadditionofKI,
thesolutionbecomesared-browncolorthatslowlyclears,evidencefortheformationandsubsequentconsumption
-
-
ofiodine(I2)andthetriiodide(I3 )anionsthatformuponreactionwithexcessI. Researchonthereactionmechanisms
andkineticsofthissystemisstillongoing. ThisdemonstrationisnearlyidenticaltoElephantToothpaste,whichuses
soaptocatchtheevolvedgases. Performingwithdimmedlightsfortheaudienceandbrighterlightontheflask
enhancestheeffect.
10
GrowlingGummyBear
RequiredTraining
UCLabSafetyFundamentals
RequiredPPE
Flame-resistantlabcoat,safetyglasses/goggles,nitrile
gloves
Equipment
25mmx200mmsilica(quartz)testtube
Labstandwithtesttubeclampandinvertedglasscone
Tongsorlongforceps
Propanetorch
Chemicals
Potassiumchlorate(KClO3)
Gummybear
Procedure:
1.)AddenoughsolidKClO3 tothesilicatubetofillittoadepthof~1”.
2.) Placethesilicatubeintheclamponthelabstand,clampingneartheopenendofthetube. Positiontheclampsuch
thatthetubeisheldvertically,withtheopeningdirectlyundertheinvertedglasscone. Therimoftheconeshould
be~1”abovetheopeningofthetube.
3.)UsethepropanetorchtoevenlyheatthebottomofthetubeuntiltheKClO3 beginstomelt.Bubbleswillstartto
formintheclearliquidasitbeginstodecompose.
4.) WhentheKClO3 isalmostfullymelted,stopheatingwiththetorchandusetongsorforcepstocarefullydropone
halfofagummybearintothetubeandstepback. Thevigorousoxidationreactionwillreleaseheat,flame,andlight
asthesugarisoxidized.TheliberatedheatfromthereactionwillmeltanyremainingsolidKClO3.
5.)IftheinitialreactiondiesdownandthereappearstobeadditionalKClO3 inthetube,asecondhalfgummybearmay
beaddedtocontinuethedemonstration. Ifitisaddedtoosoon,itislikelytobeejectedfromthetube.
Clean-up: Donotattempttomoveorcleanupthedemonstrationuntileverythinghascooledsignificantly. Oncecool,
thetubecanbecleanedwithwaterandallwasteproductscanbedisposedofdownthedrain.
Hazards: MoltenKClO3 isastrongoxidizerthatwillignitecombustiblematerialsoncontact,anditmayalsocause
thermalburns.Theoxidationofthegummibearisstronglyexothermicandproducesheat,flame,andlight. Thegummy
bearandsmalldropsofmoltenKClorKClO3 maybeejectedfromthetubebeforethereactioniscomplete,thoughthese
shouldbestoppedbytheinvertedcone.Ensurethetubeisoveranon-combustiblesurfaceasaprecaution.
Principle: Whenheatedtoamoltenstate,KClO3 decomposesintopotassiumchloride(KCl)andpotassiumperchlorate
(KClO4),whichuponfurtherheatingdecomposesintoKClandoxygen(O2). TheO2 oxidizesthesucrose(C12H22O11)inthe
gummybearintocarbondioxide(CO2)andwater(H2O);ifthereactionwenttocompletion,itwouldliberate~35kJof
energypergummybear. Theliberatedheatwillalsocaramelizesomeofthesugar,producingabrowncolorandgiving
offacharacteristicodor.Thelavendercoloroftheflameindicatesthepresenceofpotassiumion(asinaflametest).
Notes:Itispreferabletousehalfofagummybearinsteadofawholeone,asitislesslikelytobeejectedfromthetube.
Topreventthegummybearfromstickingtothetongsandthesideofthetube,itishelpfultocoatthecut(sticky)
surfacewithpowderedsugar.
11
IndicatorRainbow
RequiredTraining
UCLabSafetyFundamentals
RequiredPPE
Labcoat,safetyglasses/goggles,nitrilegloves
Equipment
Six400-mLbeakers
2-Lbeaker
Glassstirrod
Two1-Lplasticbottlesfor0.01MHClandNaOH
30-mLplasticdropperbottlefor12MHCl
30-mLplasticdropperbottlefor3MNaOH
Six30-mLplasticdropperbottleslabeledRed,Orange,
Yellow,Green,Blue,andViolet
Chemicals
Phenolphthalein
Thymolphthalein
p-nitrophenol
Hydrochloricacid(HCl),0.01M,1M,and12M
Sodiumhydroxide(NaOH),0.01Mand3M
Ethanol(EtOH),95%
Procedure:
1.) Preparationofsolutions(eachsolutionisstoredinanappropriatelylabeled30-mLplasticdropperbottle):
Red: Dissolve1.5gp-nitrophenoland0.75gphenolphthaleinin30mLEtOH. Acidifywith5dropsof1MHCl.
Orange: Dissolve2gp-nitrophenoland0.15gphenolphthaleinin30mLEtOH.
Yellow: Dissolve1gp-nitrophenolin30mLEtOH.Acidifywith5dropsof1MHCl.
Green: Dissolve0.2gthymolphthaleinand2gp-nitrophenolin30mLEtOH.Acidifywith5dropsof1MHCl.
Blue: Dissolve0.2gthymolphthaleinin30mLEtOH.
Violet: Dissolve0.45gphenolphthaleinand0.2gthymolphthaleinin30mLEtOH.
2.)Add3dropsoftheRed,Orange,Blue,andVioletindicators,and4dropsoftheYellowandGreenindicatorstothe
400-mLbeakers. ArrangethebeakersinalinerunningfromRedtoViolet,asinarainbow. Add10dropsof12M
HCltothe2-Lbeakerandsetitasideuntiltheendofthedemonstration.
3.)Filleach400-mLbeakerwith~50mLof0.01MHCl. Allsolutionsshouldremainclearandcolorless.
4.)Add~75mLof0.01MNaOHtoeachbeaker,causingarainbowofcolorstodevelopinthebeakers.
5.)ThesolutionscanbeturnedcolorlessbyfurtheradditionofHCl,andre-coloredwithNaOH. Tofinishthe
demonstration,addenoughNaOHtomakethesolutionscolored,andthenpourallofthemintothe2-Lbeaker. The
12MHClwillcausethesolutionstobecomecolorlessagain.
Clean-up:NeutralizethesolutionbytitrationwithNaOHuntilitjustbecomesyellow–thetransitionforp-nitrophenolis
completeatpH7.5. Theneutralizedsolutionmayberinseddownthesinkwithwater.
Hazards:HCl,andNaOHarehighlycorrosive,andwillcausechemicalburnsoncontact.Ethanolsolutionsare
flammable,andshouldbekeptawayfromignitionsources. Phenolphthaleinandp-nitrophenolaretoxicbyingestion,
andphenolphthaleinisapotentialcarcinogenandreproductivehazard.
Principle: Thisdemonstrationrequiresonlythreeindicatorstoproducesixcolorsoftherainbow.Eachindicatorhasan
acidicprotoninahydroxidefunctionalgroup. Inacidicsolutions,allthreeindicatorsarefullyprotonatedandappear
colorless;however,inbasicsolutionstheybecomedeprotonated,givingrisetocoloredanions--phenolphthalein
appearsred(fucshia),p-nitroanilineappearsyellow,andthymolphthaleinappearsblue.Thesethreecolorscanbe
combinedinappropriateratiostogiveanycoloroftherainbow,similartohowLCDmonitorsusered,green,andblue
pixelstorecreatevibrantimages. Alternatingbetweenacidicandbasicconditionswillreversiblydecolorizeandre-
colorizethesolutionsastheindicatorsswitchbetweenprotonatedanddeprotonatedforms.
Notes:Thisdemonstrationcanalsobeperformedonasmallerscalebyadding1-2dropsofeachindicatorsolutionto6
testtubesthatarehalffilledwithwater. ThecolorscanbeproducedorremovedbyaddingdropsofHClorNaOH,and
allofthetubescanbepouredintoasingle100-mLbeakercontaining1dropof12MHCltofinishthedemonstration.
12
InstantCoca-Cola
RequiredTraining
UCLabSafetyFundamentals
RequiredPPE
Labcoat,safetyglasses/goggles,nitrilegloves
Equipment
Empty581-mL(20-oz)Coca-Colabottle
Threegraduated20-mLbeakersorvials,labelledSolution
1,Solution2,andSolution3.
Chemicals
Solublestarch
Potassiumiodate(KIO3)
Sodiumsulfite(Na2SO3)
Sulfuricacid(H2SO4),18M
Procedure:
1.) Preparationofsolutions:
Solution1: add0.4gsolublestarchto200mLboilingwater. Letcooltoroomtemperaturebeforeuse.
Solution2:add4mLH2SO4 to200mLwater,thenadd10gKIO3 andstiruntildissolved.
Solution3:add4.2gNa2SO3 to200mLwaterandstiruntildissolved.
2.) Place~500mLofwaterinsideaclean,emptyCoca-Colabottle. Thiscomestojustabovethetopofthelabel.
3.)Add10mLofSolution1(starch),thenrecapthebottleandshakewellforseveralseconds.
4.)Add15mLofSolution2(KIO3/H2SO4),thenrecapthebottleandshakewellagain.
5.)Add15mLofSolution3(Na2SO3),thenquicklyrecapthebottleandshakeverywellfor~3-5secondstothoroughly
mixthecontents.AssoonasSolution3isadded,havetheaudiencestartcountingup,asitwillonlytake10-15
secondsbeforethesolutionabruptly(almostinstantaneously)turnsadarkblue/blackcolor.
Clean-up: Washthebottleoutwithwater. Allwastecanberinseddownthedrain.
Hazards:KIO3 isanoxidizerandshouldbekeptawayfromflammablematerialsandreducingagents.H2SO4 isstrongly
oxidizingandcorrosive,andwillcauseimmediatechemicalburnsoncontact.
-
-
Principle: Bisulfiteanions(HSO3 )fromNa2SO3 reduceKIO3 toformiodideanions(I),whichfurtherreactwithKIO3 to
-
-
-
-
formiodine(I2).InsolutionI
2 reactswithI -toformtriiodideanions(I
3 ).I3 isimmediatelyreducedbacktoI byany
-
-
remainingHSO3 .OncethesupplyofHSO3 isexhausted,I3 persistsinsolutionandreactswithstarchmoleculestoform
adarkbluestarch-iodinecomplex. ExcessI3- isabrowncolorinsolution,andtogetherthisproducesthedark
blue/black/browncolorofcoca-cola.AstheconcentrationofI 3- risesextremelyquickly,thecolorchangeisalmost
instantaneous. ThevolumeofSolution3(Na2SO3)addedtothereactionwillchangethetimerequiredforthecolor
change–largervolumeswillincreasethedelay,andsmallervolumeswilldecreaseit.
-
-
Notes:Ithasnotyetbeenconclusivelydeterminedifstarch-I3 orstarch-I5 isresponsiblefortheblue-blackcolor.
Severaldifferentproblemscanbeencounteredwiththisdemo,eachrelatingtoadifferentstartingsolution:
1. Thesolutiongraduallytransitionstoamediumbrowncolor,ratherthananabruptchange,indicatingaproblemwith
thestarchsolution. Makesurethemixtureisbroughttoaboilinordertodissolveasufficientamountofstarch.
Overtimebacteriawilleatthestarchanddecomposethesolution;ifthisoccurs,remakeSolution1.
2. Thesolutiontakesaverylongtime(>25-30seconds)beforetheabruptcolorchangeoccurs,indicatingaproblem
withtheKIO3 solution. OveralongperiodoftimetheKIO3 cancrystallizeoutofthesolution;ifthisoccurs,remake
Solution2.
3. Thesolutionchangestoadarkblue/blackcolormuchtooquickly(<5seconds),indicatingaproblemwiththeNa2SO3
solution. Na2SO3 isslowlyoxidizedbyairtoNa2SO4,losingitsreducingability;ifthisoccurs,remakeSolution3.
13
InstantFire
RequiredTraining
UCLabSafetyFundamentals
RequiredPPE
Flame-resistantlabcoat,safetyglasses/goggles,nitrile
gloves
Equipment
Wide-mouthscrew-topglassjarsformixing/storage
Plasticdropperbottleforsulfuricacid
Ceramiccrucibles
Flame-proofsurface(orconcrete)
Chemicals
Potassiumchlorate(KClO3)
Powderedsugar(C12H22O11)
Sodiumnitrate(NaNO3),potassiumnitrate(KNO3)
Strontiumnitrate(Sr(NO3)2),bariumnitrate(Ba(NO3)2)
Sulfuricacid(H2SO4),18M
Procedure:
1.)Topreparetheinstantfiremixtures,weighout20geachofNaNO3 (yellow),KNO3 (lilac),Sr(NO3)2 (red),orBa(NO3)2
(green)intotheglassjarlabeledforeachcolormixture.Add10gofKClO3 and10gofpowderedsugartoeachjar
andreplacethescrewtops. Gentlyshaketheclosedjarstothoroughlymixthepowders–DONOTgrindthem
togetherinamortar,asthefrictioncouldcausethemixturetoignite.
2.) Pour10-20goftheinstantfiremixtureintoaceramiccrucible,oneforeachcolor.
3.)Setthecruciblesonafire-proofsurface,suchasconcrete. Makesurethecruciblesareatleast2feetfromeach
other,topreventaccidentalignitionbyflyingsparks.
4.) Drop1-2dropsofH2SO4 ontooneoftheinstantfiremixturesandstepaway. Themixturewilligniteafterafew
secondsandburnintenselyfor10-15seconds,dependingonthevolumeofthemixtureinthecrucible.Ifthe
mixturefailstoignitewiththefirstdropsofH2SO4,wait10-20secondsbeforeaddinganother1-2drops. Caution–
thecombustionmaysendsparksandsmallamountsofburningsaltmixtureflyingupto1-2feetaway,andthe
extremeheatmaycausetheceramiccrucibletoshatter. Keeptheaudienceandotherperformersatleast10feet
fromthedemo.
Clean-up: Allowthecruciblestocoolcompletelybeforeattemptingtomovethem.Oncecool,theremainingsolidsin
thecruciblethatcontainedBa(NO3)2 shouldbecollectedanddisposedofashazardouswaste,whilethesolidsfromthe
othermixturesmayberinseddownthedrainwithwater.
Hazards:H2SO4 isstronglyoxidizingandcorrosive,andwillcauseimmediatechemicalburnsoncontact.Itmustbe
storedinasealedsecondarycontainertopreventaccidentalignitionofthebulkinstantfiremixtures. Theceramic
crucibleswillbecomeextremelyhotduringthedemonstration,andcouldcausethermalburns.Ifacrucibleshatters,
waituntilthepieceshavecompletelycooledbeforesweepingthemup.Ba(NO3)2 anditsdecompositionproductsare
toxic,andshouldnotbereleasedintotheenvironment.
Principle: KClO3 reactswithH2SO4 toproducechloricacid(HClO3),whichisextremelyreactiveandwillcause
spontaneousignitiononcontactwithanyorganicmaterials,suchassugar. Themetalnitratesalsoactsasoxidizersto
supportcombustion,andtheheatofthereactioncauseselectronicexcitationsinthemetalcations,whichthenemit
lightatcharacteristicwavelengthsastheyrelaxbacktothegroundstate:sodiumemitsyellow;potassiumemitslilacor
violet;strontiumemitsred;andbariumemitsgreen.
Notes:Thesodiumandstrontiummixturesproducethebrightestcolors,andtheaudienceshouldbewarnednotto
lookdirectlyatthesemixtureswhiletheyareburning. Thegreencolorofthebariummixtureisslightlyhardertosee,
andthepotassiummixtureappearsalmostwhiteindirectsunlight. Foramoreefficientburn,thereagentsshouldbe
finepowdersbeforemixing;eachcomponentmaybegroundinamortarseparatelyfor1-2minutes,providedthe
mortariscleanedbetweencomponentstopreventcross-contaminationthatcouldleadtospontaneousignition.
14
LiquidNitrogen
RequiredTraining
UCLabSafetyFundamentals
OnlineCryogenSafetyatUCDavis
RequiredPPE
Labcoat,safetyglasses/goggles,hearingprotection,
cryo-gloves(bluefabric)
Equipment
Insulatedcryogentransferdewar(1-,4-,or10-L)
Styrofoamcooler
Tongs
Itemstofreeze(flower,balloons,rubbertubing,etc.)
Electrickettlefilledwithwater
Chemicals
Liquidnitrogen(LN2)
Procedure:
1.)CarefullypourLN2 intoaStyrofoamcoolerfromthetransferdewar.
2.) DipitemsintotheLN2 untilfrozen. Usetongsandcryogenglovestoholditemstobefrozen. Donotimmerse
cryogenglovesinliquidnitrogen. Whenfreezingitems,immersethemslowlytominimizesplashingfromboil-off.
3.)Oncefrozen,itemscanbebrokenbyhandorbyhittingthemontheground.
4.)Anaudiencemembermaybeallowedtofreezeaflower,providedtheyarewearingproperattireanddonfullPPE.
Besurethattheflowerhasanythornsremovedbeforehand.
Clean-up: AnyremainingLN2 intheStyrofoamcoolermaybeemptiedontheground,producingafogeffectforthe
audience.NeverpourLN2 intoadrainorotherconfinedspace.LN2 leftinthetransferdewarwillboiloffcompletely.
Besuretocleanupanypiecesofshattereditems.
Hazards: LN2 boilsat-196°C(77K),andwillcausefrostbiteoncontact. DonotallowLN2 tobecometrappedagainstskin
–ensurethatpantsareuncuffedandcoveranypermeableopeningsonthetopsofshoes.DonotstoreortransportLN2
inenclosedspaces(i.e.elevators,carswithwindowsrolledup),asthevaporizednitrogenwilldisplaceoxygenandcan
createanasphyxiationhazard.Furthermore,neverkeepLN2 insealedcontainers,asthepressurebuild-upwill
eventuallycausethevesseltorupture,potentiallycausinggreatphysicalharmtoanyonenearby.
Notes:Neverpourliquidnitrogenonanypartofaperson,asitmaybecometrappedbyclothingandcausefrostbite.
Neverthrowliquidnitrogenupintotheair–anyliquidthatdoesnotboiloffwillfall,andposesahazardtoanyone
standingnearby.Additionally,donoteatfrozenfooditems(grahamcrackers,pretzels,marshmallows)orofferthemto
theaudience. Thishasbeendoneinpreviousyears,butthereisasmallriskoffrostbiteifasignificantamountofliquid
nitrogenisabsorbedintothefood. Italsosendsthewrongmessagetotheaudience–thereshouldnotbeany
consumptionoffoodordrinkduringachemistryperformance.
Principle:FreezingitemsinLN2 isaphysicalprocessinwhichthelowtemperatureoftheLN2 liquefiesorsolidifies
whateverobjectitcomesincontactwith,thusincreasingtheviscosityoftheobject.Iftheobjectishydrated,suchasa
flower,thentheLN2 willfreezethewaterandmaketheflowershatterlikeglass.Liquidnitrogenisconstantlyboiling,as
itisexposedtoconditionsmuchwarmerthanitsboilingpoint.Asliquidnitrogenisexposedtotheair,itcondensesany
watervaporintoawhitemistthatcanbeseenatthetopofthecontainer.
15
Examplesofitemstofreeze:
• flowersorotherplantscanbefrozenandthenbrokenbyhand,oronasurface.
• elastomers(rubberbands,Tygontubing)canbeshatteredwhenfrozen,butbecomeflexibleagainwhenwarmed.
Caution–whenfreezingTygontubing,placinganopenendofthetubeintotheliquidnitrogenwillcreateafountain
fromtheotherendofthetube.Ensurethattheopenendisnotpointedatanyone.Alsotakecarewhenbreaking
Tygontubingtopreventshatteredpiecesfromflyingtowardstheaudience;itisbettertocrushitwithahammer
thantosmashthetubingontheground.
• balloonscanbeimmersedinliquidnitrogenandshrunkdownastheairinsideliquefies. Theballoonwillre-inflate
whenwarmed,providedthelatexwasnotcrackedwhenfrozen. Heliumballoonswillnotfullycollapse,ashelium
condensesat4.2K,muchlowerthantheboilingpointofLN2.
• bananas,iffrozenfor>2minutes,canbeusedtohammernailsintowoodorotherobjects. Caution–never
positionyourhanddirectlyoverthenail,asthebananamayshatteronimpactandyourhandcouldcontinue
downwardontothenail,causingsignificantinjury.
• boilingwatermaybedumpedintoacontainerofliquidnitrogen,providedtheaudienceisgreaterthan15feetaway
andtheperformeriswearinghearingprotection.Thiswillcauseanimpressivelylargeplumeofwatervaportoerupt
fromthecontainer,andtheexpansioncanbequiteloud.Thereisatechniquetomaximizethesizeofthe
plumeofwatervapor–thecontainerofboilingwaterisheldatchestlevel,withtheperformerstandingatarm’s
lengthfromtheStyrofoamcooler;theperformerquicklyinvertsthecontainerofwaterandforcefullydirectsthe
contentsintothecenterofthecoolerinasingledownwardmotion,suchthatallofthewaterhitstheLN2 once.This
frequentlyproducesenoughforcetobreakawayoneofthewallsofthecooler,soitshouldperformedafterall
otherdemonstrationsinvolvingLN2.Larger,shallowercoolersworkbest,whilesmallercoolersaremorelikelytobe
destroyed.
16
Luminol
RequiredTraining
UCLabSafetyFundamentals
RequiredPPE
Labcoat,safetyglasses/goggles,nitrilegloves
Equipment
“ChemistryClub”neon-styleglasstubingoncardboard
Amber1-LbottleforLuminolAsolution
1-LbottleforLuminolBsolution
Bottletocatchspentluminolsolution
Chemicals
3-aminophthalhydrazide(luminol)
SodiumCarbonate(Na2CO3)andbicarbonate(NaHCO3)
Ammoniumcarbonatemonohydrate((NH4)2CO3·H2O)
Coppersulfatepentahydrate(CuSO4·5H2O)
Hydrogenperoxide(H2O2),30%solution
Procedure:
1.) Preparationofsolutions(for1Lofeach):
TomaketheLuminolAsolution(light-sensitive,storeinamberbottle),dissolvethefollowingin1LdeionizedH2O:
4gNa2CO3
0.2gluminol
24gNaHCO3
0.5g(NH4)2CO3·H2O
0.4gCuSO4·5H2O
TomaketheLuminolBsolution,dissolve5mLH2O2 in1LdeionizedH2O.
2.) Propthe“ChemistryClub”glasstubingupagainstawallorhavetwoperformersholditupright. Makesurethatthe
outlettubeisopenandisheldabovethelevelofthefunnelattachedtothetopoftheglasstubing.
3.) Withthelightsoff,simultaneouslypourequalvolumesofLuminolAandLuminolBintothefunnelattachedtothe
topoftheglasstubing.Pourslowlytoavoidvapor-lockingthefunnel,andmakesurethatthesolutionisflowing
throughtherestofthetubing.
4.)Afterthedemonstrationiscomplete,placetheoutlettubeintoabottleanddrainthesolutionfromtheglasstubing.
Clean-up: Collectthespentluminolsolutionfordisposalashazardouswaste. Thoroughlyrinsetheglasstubingwith
waterandallowittodry.
Hazards: 30%H2O2 iscorrosiveandstronglyoxidizing,causingimmediatechemicalburnsoncontactwithskin. Always
wearnitrilegloveswhenpreparing,performing,orcleaningupthisdemo.CuSO4 istoxicifingested,andisharmfulto
theenvironment.
Principle: TheCu2+ catalyzesthedecompositionofH2O2,producingoxygen(O2). Inthepresenceofhydroxideions(OH-
),thedi-anionicformofluminolisoxidizedbyO2,forminganunstableorganicperoxide.Thisdecomposestoanexcited-
statemolecule,whichthenrelaxestoalowerenergystateandemitstheexcessenergyasaphotonofbluelight.The
ironinhemoglobincanalsoactasacatalyst,allowingforensicchemiststouseluminoltodetecttraceamountsofblood
atcrimescenes.
Notes:Thecurrent“ChemistryClub”signisextremelydifficulttouseforthisdemonstration,asmanyofthebendsare
sharpenoughtopreventcontinuousflow,andinsteadcausethefunneltovaporlock. Itmaybemoreimpressivetomix
thetwosolutionsinalargespiraltubeorevenalargeflask,astheluminescenceonlylastsforafewmoments.
SourceforLuminol:
-Aldrich,Cat#12,307-2: 3-Aminophthalhydrazide
17
Magnesium/DryIce
RequiredTraining
UCLabSafetyFundamentals
OnlineCryogenSafetyatUCDavis
RequiredPPE
Flame-resistantlabcoat,safetyglasses/goggles,
cryo-gloves(bluefabric)
Equipment
Drillwith2”holesawbit
Styrofoamcoolerfortransportingdryice
Propanetorch
Chemicals
Magnesium(Mg)ribbon
SolidCO2 (dryice),2slabs
Procedure:
1.) Drillahole(2”diameter)inthemiddleofaslabofdryice,approximately1/3ofthewaythroughit. Then,withthe
drillturnedoff,usetheedgeoftheholesawbittochipoutthediscinthemiddle,leavingacirculardepression.The
backofaclawhammercanalsobeusedtopryoutthedisc. Takecarenottocracktheslabwhendoingthis.
2.) Placetheslabwiththeholeontheground,withtheholefacingup,atleast10feetfromtheaudienceandaway
fromflammablematerials.
3.) Wrapa0.5-meterlengthofMgribbonaroundapencilorsimilarlysizedobjecttoformatightcoil. Then,wrapthis
coilintoaspiral,suchthatitwillfitinthecircularholeintheslabofdryice.
4.) Withasecondperformerholdingthesolidslabofdryiceattheready,placethecoilofMginthecircularholeand
usethetorchtoigniteit. AssoonastheMgstartstoburn,thesecondperformermustquicklyplacethesolidslabof
dryiceontopoftheother,takingcarenottocrackeitherslab.
5.)Standbackfromthedemo,assparksofburningMgwillescapebetweentheslabsandflyupto1footaway.
Clean-up: Oncethemagnesiumhascompletelycombusted,thedryicemaybereturnedtoitscooler.Aftertheshow,
theashesoftheMgribbonmaybediscardedinthetrash,andthedryiceplacedinthefumehoodofroom272untilit
completelysublimes.
Hazards: Dryicesublimesat-78.5°C(194.5K),andprolongedcontactwithskinwillcausefrostbite. Neverplacedryice
inaclosedcontainer,asthebuild-upofpressuremaycauseittoburst,whichcouldinjureanyonenearby. Mgisa
flammablesolidandburnsatextremelyhightemperatures(>3000°C),simultaneouslyproducingverybrightwhiteand
UVlight.Hazardsincludethermalburnsandvisiondamageifthecombustionisvieweddirectly.
Principle:InitiallytheMgburnsinaconventionalmanner,usingoxygenfromtheair. Afterafewsecondsthelightwill
dim,andatthispointtheatmosphericoxygenisbeingcompletelyconsumedintheburningchamber(thespace
betweentheslabs).However,Mghassuchapowerfulaffinityforoxygenthatitbeginstostealoxygenfromthedryice,
producingmagnesiumoxide(MgO)andcarbonsoot. Thereactionthenproceedsmuchfasterandthelightgets
brighter,andtheMgwillcontinuetoburnuntilallofithasbeenconsumed.
Notes:Thisdemonstrationismostimpressivewiththelightsdimmed.TheMgribbonshouldnotbeplacedinthedryice
significantlybeforethedemonstration,asthisseemstodiminishtheintensityofthereaction. Usinglargerquantities ofMgribbonalsoappearslessimportanttotheintensityofthereactionthanproperlyoptimizingtheavailablesurface
area;asmallerpiecethathasbeencarefullycoiledandwoundburnsjustasbrightlyasamuchlargerpiececrumpledinto
aball.
18
SilverMirrorinaFlask
RequiredTraining
UCLabSafetyFundamentals
RequiredPPE
Labcoat,safetyglasses/goggles,nitrilegloves
Equipment
1-LFlorenceflaskwithstopper
Three500-mLbottles(oneamberglass,labelledSolution
A,twoplastic,labelledSolutionsBandC,respectively)
OneplasticdropperbottleforNH4OHsolution
One1-Lplasticbottleforwasteneutralization,labelled
“NeutralizationSolution”
10-and50-mLgraduatedcylinders
3-mLplasticpipette
Washbottlefilledwithdeionizedwater
Filtrationapparatus(forrecyclingsilver)
Chemicals
Silvernitrate(AgNO3)
Potassiumhydroxide(KOH)
Sucrose(C12H22O11)
Nitricacid(HNO3),16M
Ethanol(EtOH),≥95%solution
Ammoniumhydroxide(NH4OH),6M
Hydrochloricacid(HCl),1M
Ascorbicacid(C6H8O6)
Procedure:
1.) Preparationofsolutions:
SolutionA: Dissolve10gAgNO3 in400mLdeionizedH2O(0.15MAg(NO3). Storeina500-mLamberglassbottle.
SolutionB: Dissolve18gKOHin400mLdeionizedH2O(0.8MKOH).Storeina500-mLplasticbottle.
SolutionC: Dissolve40gsucrose,1.75mLHNO3,and50mLEtOHin400mLdeionizedwater. Boilthissolutionina
beakeronahotplatefor30minutesbeforeuse,orallowittoageforonemonthatroomtemperature.Storeina
500-mLplasticbottle.
Wasteneutralizationsolution: Add200mLHCltoa1-Lplasticbottle.
2.) Makesurethattheflasktobesilveredisabsolutelyclean,otherwisethemirrorwillnotdepositproperly.
3.)Add40mLofSolutionA(AgNO3)totheflask,andthentitratethesolutionwith6MNH4OHwhileswirlingtheflask
constantly. Thiswillinitiallyformabrownprecipitate,butuponfurtheradditiontheprecipitatewillclear. Stop
addingNH4OHassoonastheprecipitateclears.
4.)Add20mLofSolutionB(KOH)totheflask;thiswillproduceacream-coloredprecipitate. TitrateagainwithNH4OH,
butthistimestoptheadditionjustbeforetheprecipitateclears(seeNotes).
5.)Add5mLofSolutionC(sucrose)andquicklystoppertheflaskandbeginswirlingthesolutionvigorously,constantly
coatingalloftheinteriorsurfaces. Makesuretoholdthestopperinplacewithonehandwhileshakingtheflask.
Theflaskwillstarttobecomedarker,andthenappearblack,butcontinuedswirlingwillresultinthedepositionofa
shinysilvermirrorontheinteriorsurfaceoftheflask.
6.)After1-2minutesofshaking,thesilveriscompletelydeposited. Removethestopperandpourthesolutionintothe
1-Lbottlewiththewasteneutralizationsolution,whichwillresultinacloudywhiteprecipitateofsilverchloride
(AgCl)mixedwithsomegraymetallicsilver(Ag)thatdidnotdepositonthewalls. Usethewashbottletorinsethe
insideoftheflaskthoroughly(4-5times),withallrinseatesbeingcollectedinthewasteneutralizationbottle.
Clean-up: Aftertheshow,themirrorcanberemovedfromtheflaskbydissolvingitwithHNO3. Thismustonlybedone
insideachemicalfumehood,asitgenerateshighlytoxicNO2 gas.Oncethesilverisdissolvedout,allowthenitricacid
solutiontoevaporate,leavingcrystalsofAgNO3 thatmaybereusedinfuturedemonstrations.
Hazards:HCl,HNO3,KOH,andNH4OHarehighlycorrosive,andwillcausechemicalburnsoncontact.NH4OHalsogives
offnoxiousNH3 fumes,andshouldbehandledwithcare.AgNO3 solutionswillstainskin/clothing/anythingdarkbrown
orblack. Ifallowedtoevaporate,basicsolutionscontainingNH4OHandAgNO3 canproduceblackcrystalsofAg3N,a
highly-unstable,shock-sensitiveexplosivecompound. Alwayspourthespentsilveringsolutionandflaskrinsingsintothe
wasteneutralizationcontainer,asthispreventstheformationofAg3N.
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Principle: ThisdemonstrationusesthechemistryofTollens’testforaldehydestoproduceasilvermirrorontheinside
ofaglassflask. AgNO3 reactswithNH4OHinbasicsolutionstoformdiamminesilvercations([Ag(NH3)2]+),whichcanbe
reducedbyaldehydesorα-hydroxyketonestoformmetallicsilver(Ag). Thesucroseisslowlyhydrolyzedinacidic
solution(orquicklyatelevatedtemperature)toproduceglucoseandfructose,whichhavealdehydeandα-
hydroxyketonefunctionalgroups,respectively,intheirfleetingopen-chainconformations.Thesesugarsreducethe
diamminesilverintometallicsilver,someofwhichgetsdepositedonthesurfaceasasilvermirror.Theremaining
silveringsolutionisaddedtoabottlecontainingHCl,whichwillreactwithanyAg+ ionsinsolutiontoformthe
notoriouslyinsolublecompoundAgCl.Bydoingthis,thepossibilityofformingexplosivecompoundsiscompletely
eliminated,andallofthesilverisreclaimedasasolidthatcanberecycledforfutureuse.
Notes:Thesecondtitrationsteprequiresabitofpracticetoknowwhenitiscomplete.Asthetitrationproceedsthe
precipitatewillbegintodissolveslowly,andthecolorchangewillnotbeapparentuntilthelastfewdropsofthe
titration.Over-titratingisnottheendofthedemonstration,butitwillcauselessofthesilvertoprecipitateoutinthe
mirror.ThetitrationcanbereversedbyaddingmoreofSolutionA. OnceallofSolutionAisusedup,alargeportionof
thesilvercanbereclaimedfromthewasteneutralizationsolution;thesolidAgandAgClarecollectedbyfiltrationand
washedwithwatertoremoveanyexcessCl-,andthenredissolvedinNH4OH.Addtothissolutionanexcessofascorbic
acid(C6H8O6),whichwillcauseallofthesilvertoimmediatelyprecipitateoutasagrayflocculentpowderwithout
depositingonthewallsofthevessel. ThesolidAgisthencollectedbyfiltrationandwashedwithwateragain,andcan
beconvertedbacktoAgNO3 usingthemethoddescribedintheClean-upsection,takingappropriateprecautions.Ifthe
silvermirrorisintendedtobekeptintheflaskforanylengthoftime,itisbesttocoverthesilverwithanimpermeable
barrier(varnish,nailpolish,paint,etc.)topreventtarnishingandprotectthemirrorfromscratches.
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TrafficLightReaction
RequiredTraining
UCLabSafetyFundamentals
Equipment
500-mLFlorence/Erlenmeyerflask(orlarger)
Rubberstoppertofitflask
RequiredPPE
Labcoat,safetyglasses/goggles,nitrilegloves
Chemicals
Dextrose(D-glucose,C6H12O6)
Potassiumhydroxide(KOH)
Indigocarmine(I.C.),1%solution
Procedure:
1.)Add300mLwater,8gKOH,and10gdextrosetotheflask,swirlingthesolutionuntileverythinghasdissolved.
2.)Add5-10dropsoftheI.C.indicatorsolution,swirlingagaintomix. Thesolutionwillinitiallyturngreen,butaftera
fewmomentsitwillbecomeyellow.
3.)Toperformthedemo,stoppertheflaskandshakethesolutionvigorously,makingsuretoholdthestopperinplace
withonehand.Thesolutionwillturnred,andthengreenaftersufficientshaking. Afterthesolutionhasturned
green,stopshakingandletthesolutionrestfor;itwilltransitionbackthroughredandbecomeyellowagain.
4.)Thisreactioncanberepeatedseveraltimes(occasionallyupto8)beforethesolutiondecomposesandturnscloudy.
Clean-up: Thewastesolutionmayberinseddownthesinkwithcopiousamountsofwater.
Hazards:KOHisastrongbaseanditssolutionsarehighlycorrosive,causingimmediatechemicalburnsoncontact.
Principle: Thisdemonstrationinvolvesareversibleoxidation-reductionreactionbetweenI.C.,oxygen(O2),anda
reducingsugar.I.C.isabothapHandaredoxindicator;theoxidizedformisbluebelowpH11.4,yellowabovepH13,
andgreenintheintermediaterange,whilethereducedformisyellowatallpHlevels. Whentheflaskisshaken,
atmosphericO2 isdissolvedinthesolutionandoxidizestheI.C.toitsgreenform. Dextroseisareducingsugar,andin
alkalinesolutionitisconvertedtoanenolatewhichreducestheI.C.firsttoaredsemiquinoneintermediateandfinally
totheyellowreducedform;thedextroseisultimatelyoxidizedintoarabinonicacidandformateanions. Shakingthe
flaskagainintroducesmoreoxygen,whichrepeatsthecycleuntilnodextroseremains.
Notes: ThisisessentiallythesameastheBlueBottledemonstration,onlyadifferentindicatorisused.Inthiscase,the
colorschangesarestronglydependentonthepHofthesystem;abovepH13,theoscillationisbetweenyellow,red,and
yellow,whereasbelowpH11.4thecolorshiftsthroughblue,purple,red,orange,andyellow. Thismakesfora
somewhatmoreinterestingdemonstration,butwouldberatheroddforatrafficlight. Thestructuresofthereduced
formsoftheI.C.indicatorarenotfullydetermined,anditisthoughtthatthegreencolorcomesfromamixingofthe
blueandyellowforms.
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VinegarCannon
RequiredTraining
UCLabSafetyFundamentals
RequiredPPE
Labcoat,safetyglasses/goggles,nitrilegloves
Equipment
Smallplasticbottle(withnarrowneck)
Corktofitbottle
Tissuepaper/kimwipe(alternateprocedure)
Smallmarble(alternateprocedure)
Chemicals
Sodiumbicarbonate(NaHCO3)(bakingsoda)
Aceticacid(CH3COOH),5%solution(vinegar)
Procedure:
1.) Place~1-2gramsofbakingsodainthebottle.
2.) Pourabout20mLofvinegarintothebottle.
3.)Quicklyinsertthecorkintheneckofthebottle,andthenswirlthebottletomix.Makesuretheneckofthebottleis
notpointedatpeopleoratfragilematerials,andholdthebottlefirmly.
4.) WhenthepressurefromtheevolvedCO2 becomesgreatenough,thecorkwillflyoutofthebottle. Dependingon
howtightlythebottleiscorked,itcanflyupwardsof10-20feet.
Alternateprocedure:
1.) Pour~20mLofvinegarintothebottle,makingsuretokeeptheneckofthebottledry.
2.) Placeapieceoftissuepaper/kimwipeovertheneckofthebottleandpushaportionofitintothebottleusingyour
finger.Thiscreatesasmallpouchsuspendedfromthetopofthebottle.
3.) Whileholdingtheedgesofthetissuepapertokeepitfromfallingintothebottle,add~1-2gramsofbakingsodaand
asmallmarbletothepouch.
4.) Pushthecorkintotheneckofthebottle,wedgingthetissuepaperinplace. Theexcesstissuepapercanthenbecut
ortornawayfromtheneckofthebottle,takingcarenottodislodgethecork. Keepthebottleuprighttoprevent
prematuremixingofthebakingsodaandvinegar.
5.)Toactivatethedemo,sharplylowerthebottleontoatable,suchthatthemarblebreaksthroughthetissuepaper
andallowsthebakingsodatofallintothevinegar. Alternatively,youcaninvertthebottleandstanditonthecork,
suchthatthebottlelaunchesupwards(inthiscasethemarblemaybeomitted).
Clean-up: Allwastemayberinseddownthedrainwithwater.
Hazards:Thecorkscanpopoutofthebottlewithsignificantforce,andcouldtheoreticallybreaksomethingfragileor
causeaninjuryifpointedatsomeone.
Principle: ThereactionbetweenNaHCO3 andCH3COOHproducescarbondioxide(CO2)thatcan’tescapetheclosed
bottle;thiscausesthepressuretobuilduntilthecorkout.
Notes:Audiencemembersmaycomeuptoperformthesedemosprovidedtheyarewearingproperattireanddonfull
PPE.Ifperformingthedemousingthefirstmethod,thebottlemustbecorkedveryquickly,otherwiseitturnsintoa
verysimplebakingsoda/vinegarvolcanoinyourhand.
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