6b Hot Pack Calorimetry - Health and Science Pipeline ... · Hot Pack Calorimetry Teacher...
Transcript of 6b Hot Pack Calorimetry - Health and Science Pipeline ... · Hot Pack Calorimetry Teacher...
HASPIMedicalChemistryUnit6:Energy Lab6b, Page1
HASPIMedicalChemistryLab6bHotPackCalorimetryTeacherInformationLabOverviewInthislabstudentsmeasuretheamountofenergyreleasedinthetypeofreactionthatoccursinahotpack.BylinkingthistothehydratedcrystalslabinthefallwherestudentsheatedEpsomsalts(magnesiumsulfatehydrate)untiltheylostallwater,studentsareabletoquantifytheenergythattheystoredintheiranhydratepelletsincethelastlaboccurred.ToquantifythistheymustdissolvetheanhydrateinwateraswellasthehydrateanduseHess’lawtofindthedifference.Theanhydratedissolvinginwaterisanexothermicreaction.Thehydrate(Epsomsalts)dissolvinginwaterisaslightlyendothermicreaction.Studentswillexperiencebothtypesofreactionsinthislab,andtheywillturnpotentialenergytheyputintotheiranhydrateinthepreviouslabbackintokineticenergywhichtheycanmeasureastheincreaseinwatertemperature.NextGenerationScienceStandards
NGSS/CommonCoreStateStandardsStudentswhodemonstrateunderstandingcan:HS‐PS1‐4:Developamodeltoillustratethatthereleaseorabsorptionofenergyfromachemicalreactionsystemdependsuponthechangesintotalbondenergy.HS‐PS3‐1:Createacomputationalmodeltocalculatethechangeintheenergyofonecomponentinasystemwhenthechangeinenergyoftheothercomponent(s)andenergyflowsinandoutofthesystemareknown.HS‐PS3‐3:Design,buildandrefineadevicethatworkswithingivenconstraintstoconvertoneformofenergyintoanotherformofenergy.HS‐PS3‐4:Planandconductaninvestigationtoprovideevidencethatthetransferofthermalenergy,whentwocomponentsofdifferenttemperaturesarecombinedwithinaclosedsystem,resultsinamoreuniformenergydistributionamongthecomponentsinthesystem(secondlawofthermodynamics).MedicalApplication:Hotpacksandcoldpacksarechemicalreactionsthatstudentswillstudy.
ScienceandEngineeringPracticesDevelopingandUsingModelsDevelopamodelbasedonevidencetoillustratetherelationshipsbetweensystemsorbetweencomponentsofasystem.UsingMathematicsandComputationalThinkingCreateacomputationalmodelorsimulationofaphenomenon,designeddevice,process,orsystem.ConstructingExplanationsandDesigningSolutionsDesign,evaluate,and/orrefineasolutiontoacomplexreal‐worldproblem,basedonscientificknowledge,student‐generatedsourcesofevidence,prioritizedcriteria,andtradeoffconsiderations.PlanningandCarryingOutInvestigationsPlanandconductaninvestigationindividuallyandcollaborativelytoproducedatatoserveasthebasisforevidence,andinthedesign:decideontypes,howmuch,andaccuracyofdataneededtoproducereliablemeasurementsandconsiderlimitationsontheprecisionofthedata(e.g.,numberoftrials,cost,risk,time),andrefinethedesignaccordingly.
DisciplinaryCoreIdeasPS1.A:StructureandPropertiesofMatterAstablemoleculehaslessenergythanthesamesetofatomsseparated;onemustprovideatleastthisenergyinordertotakethemoleculeapart.PS1.B:ChemicalReactionsChemicalprocesses,theirrates,andwhetherornotenergyisstoredorreleasedcanbeunderstoodintermsofthecollisionsofmoleculesandtherearrangementsofatomsintonewmolecules,withconsequentchangesinthesumofallbondenergiesinthesetofmoleculesthatarematchedbychangesinkineticenergy.
DisciplinaryCoreIdeas(continued)
HASPIMedicalChemistryUnit6:Energy Lab6b,Page2
PS3.A:DefinitionsofEnergyEnergyisaquantitativepropertyofasystemthatdependsonthemotionandinteractionsofmatterandradiationwithinthatsystem.Thatthereisasinglequantitycalledenergyisduetothefactthatasystem’stotalenergyisconserved,evenas,withinthesystem,energyiscontinuallytransferredfromoneobjecttoanotherandbetweenitsvariouspossibleforms.Atthemacroscopicscale,energymanifestsitselfinmultipleways,suchasinmotion,sound,light,andthermalenergy.PS3.B:ConservationofEnergyandEnergyTransferConservationofenergymeansthatthetotalchangeofenergyinanysystemisalwaysequaltothetotalenergytransferredintooroutofthesystem.Energycannotbecreatedordestroyed,butitcanbetransportedfromoneplacetoanotherandtransferredbetweensystems.Uncontrolledsystemsalwaysevolvetowardmorestablestates—thatis,towardmoreuniformenergydistribution(e.g.,waterflowsdownhill,objectshotterthantheirsurroundingenvironmentcooldown).Mathematicalexpressions,whichquantifyhowthestoredenergyinasystemdependsonitsconfiguration(e.g.relativepositionsofchargedparticles,compressionofaspring)andhowkineticenergydependsonmassandspeed,allowtheconceptofconservationofenergytobeusedtopredictanddescribesystembehavior.Theavailabilityofenergylimitswhatcanoccurinanysystem.PS3.D:EnergyinChemicalProcessesAlthoughenergycannotbedestroyed,itcanbeconvertedtolessusefulforms—forexample,tothermalenergyinthesurroundingenvironment.ETS1.A:DefiningandDelimitinganEngineeringProblemCriteriaandconstraintsalsoincludesatisfyinganyrequirementssetbysociety,suchastakingissuesofriskmitigationintoaccount,andtheyshouldbequantifiedtotheextentpossibleandstatedinsuchawaythatonecantellifagivendesignmeetsthem(secondary).
CrosscuttingConceptsEnergyandMatterChangesofenergyandmatterinasystemcanbedescribedintermsofenergyandmatterflowsinto,outof,andwithinthatsystem.SystemsandSystemModelsModelscanbeusedtopredictthebehaviorofasystem,butthesepredictionshavelimitedprecisionandreliabilityduetotheassumptionsandapproximationsinherentinmodels.ConnectionstootherDCIsinthisgrade‐band:HS.PS1.A;HS.PS1.B;HS.PS2.B;HS.LS2.B;HS.ESS1.A;HS.ESS2.A;HS.ESS2.D;HS.ESS3.A;HS.PS3.A;HS.PS3.B;HS.PS3.D;HS.LS1.CArticulationofDCIsacrossgrade‐bands:MS.PS1.A;MS.PS2.B;MS.PS3.A;MS.PS3.B;MS.PS3.C;MS.ESS2.A;MS.PS3.D;MS.LS1.CCommonCoreStateStandardsConnections:ELA/Literacy
RST.11‐12.1 Citespecifictextualevidencetosupportanalysisofscienceandtechnicaltexts,attendingtoimportantdistinctionstheauthormakesandtoanygapsorinconsistenciesintheaccount.(HS‐PS3‐4)
WHST.9‐12.7 Conductshortaswellasmoresustainedresearchprojectstoansweraquestion(includingaself‐generatedquestion)orsolveaproblem;narroworbroadentheinquirywhenappropriate;synthesizemultiplesourcesonthesubject,demonstratingunderstandingofthesubjectunderinvestigation.(HS‐PS3‐3),(HS‐PS3‐4),(HS‐PS3‐5)
WHST.11‐12.8 Gatherrelevantinformationfrommultipleauthoritativeprintanddigitalsources,usingadvancedsearches effectively;assessthestrengthsandlimitationsofeachsourceintermsofthespecifictask,purpose,andaudience;integrateinformationintothetextselectivelytomaintaintheflowofideas,avoidingplagiarismandoverrelianceonanyonesourceandfollowingastandardformatforcitation.(HS‐PS3‐4),(HS‐PS3‐5)
WHST.9‐12.9 Drawevidencefrominformationaltextstosupportanalysis,reflection,andresearch.(HS‐PS3‐4),(HS‐PS3‐5)SL.11‐12.5 Makestrategicuseofdigitalmedia(e.g.,textual,graphical,audio,visual,andinteractiveelements)inpresentationsto
enhanceunderstandingoffindings,reasoning,andevidenceandtoaddinterest.(HS‐PS3‐1),(HS‐PS3‐2),(HS‐PS3‐5),(HS‐PS1‐4)
CommonCoreStateStandardsConnections:MathematicsMP.2 Reasonabstractlyandquantitatively. (HS‐PS3‐1), (HS‐PS3‐2), (HS‐PS3‐3), (HS‐PS3‐4),(HS‐PS3‐5)MP.4 Modelwithmathematics.(HS‐PS3‐1), (HS‐PS3‐2), (HS‐PS3‐3), (HS‐PS3‐4), (HS‐PS3‐5),(HS‐PS1‐4)HSN.Q.A.1 Useunitsasawaytounderstandproblemsandtoguidethesolutionofmulti‐stepproblems;chooseandinterpretunits
consistentlyinformulas;chooseandinterpretthescaleandtheoriginingraphsanddatadisplay.(HS‐PS3‐1),(HS‐PS3‐3),(HS‐PS1‐4)
HSN.Q.A.2 Defineappropriatequantitiesforthepurposeofdescriptivemodeling. (HS‐PS3‐1),(HS‐PS3‐3),(HS‐PS1‐4)HSN.Q.A.3 Choosealevelofaccuracyappropriatetolimitationsonmeasurementwhenreportingquantities.(HS‐PS3‐1),
(HS‐PS3‐3),(HS‐PS1‐4)
HASPIMedicalChemistryUnit6:Energy Lab6b, Page3
ObjectivesBytheendofthislabstudentswillbeableto:
Calculatetheenergygainedorlostinachemicalreactionusingcalorimetry. UseHess’lawtorelatetwoexperimentalreactionsinordertodeterminethechangeinenergyfor
thesumofthosereactions.Time
EstimatedTime
ActualTime(pleasemakenotebelow)
Pre‐Lab:20‐30Minutes
Lab:40minutesorless
PostLabCalculations:1hour
Materials
Suppliesneededfor5sections
Provided(P)or
Needed(N)
Quantity
Company/Item#
ApproximateCost
EpsomSalts P 2‐3gpergroup
Grocery/DrugStore
$3
AnhydrousmagnesiumsulfateYoushouldhavesavedthisfromlab4a*seelabnotesforanotheroption
P(ifyoudid4a)
2‐3gpergroup
FlinnM0115
$17
Studentmadecalorimetersfromlab6a 1pergroup Thermometers 1pergroup Balance GraduatedCylinderstomeasure20mLofwater
Accesstowater PrerequisiteKnowledgeStudentsshouldalreadyknowthefollowinginformation:
Theuseoftheequationq=cmΔT Thetermsendothermicandexothermic ConversionbetweenkelvinandCelsius
LabSetup Studentscanusetheirowncalorimetersfromlab6a.Ifnot,youcanmakeyourownfoamcup
calorimeter.Tomake10calorimetersbuy10largecupsand20smallcups.Placeasmallcupinsideeachlargecuptocreateaninsulateddevice.Pokeathermometersizedholeintheothersmallcupanduseitforalid.
Eachgroupneedsathermometerandwillneedtoweighouttwoseparatesubstances.Provideasmanybalancesasyouthinkyouwillneed.
CompanyContactInformationFlinnScientific
http://www.flinnsci.com/
HASPIMedicalChemistryUnit6:Energy Lab6b,Page4
LabNotes&CommonMisconceptions TheBackgroundandReviewquestionsareaperfectpre‐labassignmenttosendhomewith
studentsashomeworkbeforethelab. Ifyoudidlab4ayoushouldhavekeptthesmalldriedpellets.Itisbestiftheyarekeptinasealed
ziptopbag,butIhavestillhadsuccesswhentheyareleftout. Ifyoudidnotdolab4ayouhaveafewoptions.
o YoucanpurchasetheanhydratefromachemicalcompanysuchasFlinn.o YoucananhydratetheEpsomsaltathome.Itneedstoreachatleast450degreesto
anhydratesoyoucanputitinyourovenforawhileatahightemperature.Itshouldbeapproximatelyhalftheweightattheendasitis51.2%water.
o IfyouhaveBunsenburnersandcruciblesthestudentscancreatethemagnesiumsulfateanhydratefromEpsomsaltsbyfollowingtheprocedurelistedinlab4a.Thepelletmustbecooledbeforeitcanbeusedforthislab.Itwilltakeabout10minutestoanhydratebyBunsenburnerandanother10minutestocool.
Thesecondreactionismildlyendothermic,sostudentswillseeonlya1‐2degreechangeintemperature.TheyareoftensurprisedtoseeanendothermicreactionsoIfinditbestnottotellthemaheadoftimesotheydiscoveritthemselves.
Thefirstreactionshouldhave3significantfiguresincalculationsandthesecondreactionshouldonlyhavetwosignificantfiguresincalculationsdependingonthetemperaturechangetheysaw.It’sbestthatyoureviewsignificantfiguresrulesbeforethelabtoensuretheydotheircalculationsproperly.
Letusknowhowitwent!Gotowww.HASPI.org/feedbacktoshareyoursuggestions&successes.Connections&ApplicationLab4aandlab6ahavestrongconnectionstothislab.Ifyouhavealreadydonetheselabsyoumightreviewthemwithyourstudentsbeforedoingthislabtohelpthemmakeconnections.
Askstudentstostudythereactionsthathavetodowithcoldpacks. MRE’sor“MealsReadytoEat”areamilitarystaplethatself‐heat.Havestudentsstudythe
reactionandfindouthowmuchenergyisneededforthese. Havestudentscreateabrochureeducatingapatientonwhentouseheattherapyandcoldtherapy. Drawanenergydiagramforeachofthethreereactionsshowingthechangeinenergy. Createavideoanimationoftheprocessesobservedinthislab. Explorethethermodynamicsofotherheatpackreactioningredientssuchasironpowder.
References:http://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=1&ContentID=4483http://www.spine‐health.com/treatment/heat‐therapy‐cold‐therapy/benefits‐heat‐therapy‐lower‐back‐painhttp://www.middleschoolchemistry.com/lessonplans/chapter5/lesson9http://home.howstuffworks.com/question290.htmhttp://prezi.com/lranljsxv4hx/copy‐of‐chemistry‐hotcold‐packs/http://www.chemistryland.com/CHM130FieldLab/Lab11/Lab11.html
HASPIMedicalChemistryUnit6:Energy Lab6b, Page5
HotPackCalorimetryHASPIMedicalChemistryLab6bBackground/Introduction
Manycommonreactionsinchemistrycausetemperaturechanges.Endothermicreactionsabsorbheat,makingtheenvironmentaroundthemfeelcolder.Exothermicreactionsreleaseheat,makingtheenvironmentaroundthemfeelwarmer.Wecanusethesereactionstoprovidethermotherapysothattreatmentcanbequickandcanbeavailableanywhere.Thermotherapyistheuseofheatorcoldtotreataninjuryorillness.Weusechemicalreactionstocreateheatpacksandcoldpacks.
Coldpacksareusedmostoftentoreduceinflammationandswelling.Thisisbestforanewinjury.
Coldtherapydecreasesbloodflow Lessbloodflowleadstolessswellingandinflamation Coldtherapyisidealforanareathatisswollenorbruised Coldtreatmentisbestduringthefirst24‐48hoursafteraninjury Coldtherapyshouldoccurfor20minutesatatimewithatleast10minutesbetweenapplications
Hotpacksareusedtoprovidepainrelief.,Commonusesareforbackpainorarthritispain.Thistreatmentisbestforrecurringpain.
Bloodvesselsaredilatedsothatthereisanincreasedflowofbloodtothemuscles Bloodflowbringsoxygenandnutrientssothatdamagedtissuecanheal Theheatallowssofttissuestostretchsothatthereisdecreasedstiffnessandincreasedflexibility
Thiscangreatlyincreasetherangeofmotion Heatcanrelaxjoints,muscles,ligamentsandtendons Heattherapyshouldoccurin20minuteincrements
HotPackChemistryThereareafewwaysthatexothermicreactionscanbeusedashotpacks.Thereactionwewillstudytodaymixesanhydrousmagnesiumsulfate(MgSO4)withwater.Whenthesemixheatisreleased.InahotpackthereispowderedMgSO4alongwithasmallbagofwater.Whenyousqueezethehotpack,thewaterpacketburststobeginthereaction.Thistypeofhotpackcanonlybeusedonetime.Anothertypeofhotpackusesasupersaturatedsolutionofsodiumacetate.Sodiumacetatehasaboilingpointof130°F,butifyoumeltitbyheatingitabovethattemperature,youcancoolitbackdownanditwillstayaliquiduntilsomethingcausesjustonemoleculetofreeze.Thiscausesachainreactionuntilallofthesodiumacetatefreezes.Inorderforthemoleculestosolidifyandfreeze,theenergywithinthemmustbereleased,whichiswhythisfeelshotinyourhands.Thesehotpacksarereusableaslongasyouboilthemtodissolveormeltthesodiumacetateagain.
http://www.chemistryland.com/CHM130FieldLab/Lab11/Lab11.html
Name(s): Period: Date:
HASPIMedicalChemistryUnit6:Energy Lab6b,Page6
Ironfilingscanalsobeusedasahotpack.Theyreactwithoxygenintheair,sotheyareinameshpacketwhichissealedinsideofthepackaging.Onceopened,theironfilingsreactwiththeoxygeninthesamewaytheyreacttocreaterust,butithappensveryquicklybecausetheironisinverysmallpieces.Waterisabletospeedupthisreaction,increasingtheheatforamoment,buttheheatpackwillcoolmorequicklyifthereactionspeedsup.ColdPackChemistryEndothermicreactionscanbeusedascoldpacks.Acommonlyusedcoldpackcontainsammoniumnitrateandwater.Whenthesmallbagofwaterinsideisputunderpressureitburststobegintheendothermicreaction.Thisreactionneedsenergy,soittakestheenergyfromyou,makingyoufeelcold.Coldisjustthesensationofenergymovingawayfromyou.ANewConcept‐Calorimetry!Todaywewillusecalorimetrytostudytheenergygivenoffbyourreactions.Calorimetryallowsustomeasuretheenergygiventowaterbyareaction,orbyahotmetal.Thisisusedtofindtheamountofenergyinourfood,toidentifyunknownmetals,andinthiscase,tofindtheEnthalpyofHydrationforoursubstance.Incalorimetrywearegoingtodoareactioninaverywellinsulatedcontainer,whichwewillmakefromstyrofoamcups.Asthereactionproceeds,thewaterwillabsorbtheenergyreleased.Wecanuseathermometertomeasurethechangeintemperatureofthewater,thenusethereactionq=mcΔTinordertofindoutthequantityofenergythatwasreleased!
ReviewQuestions1. Whatisthedifferencebetweenanexothermicandendothermicreaction?2. Howdoyouchoosewhichtherapyisrightforyourinjury?3. Whywouldn'tahotpackhelpwithswelling?4. Howdoyouthinkyoumightbeabletore‐usethechemicalsinaMagnesiumSulfatehotpack?5. Ifthereactioncreatingrust(IronOxide)isexothermic,whydon'trustycarsandnailsfeel
warm?6. Whatdoesthecoldsensationmeaninchemistry?7. Whydoweneedaninsulatedcontainerforcalorimetry?8. Whaterrorsdoyoupredictwewillencounterinacalorimetrylab?
Reaction
Heat q=m c ΔT
energyinJoules
massingrams
specificheat
changeintemperature
HASPIMedicalChemistryUnit6:Energy Lab6b, Page7
HotPackCalorimetryHASPIMedicalChemistryLab6b ObjectivesFindtheamountofenergyreleasedwhenMgSO4isrehydratedtoformMgSO47H2OSpecifically:
CalculatetheEnthalpyofHydration(ΔH)forMgSO4 LearnCalorimetrytechniques ApplyHess'Law Usetheequationq=mcΔT
Materials
FoamCupCalorimeter Thermometer AnhydrousMgSO4 MgSO47H2Ocrystals
DIordistilledwater DigitalBalanceandweighboats 50mlor100mLGraduatedcylinder
ConnectionstopastlabYoupreparedtheanhydratebyheatingtheMgSO47H2O(s)lastsemesterinthehydratedcrystalslab.Ittookheattoremovethewaterfromthecrystals,whichmeantitwasanendothermicreaction.ThatenergyhasbeenstoredintheanhydrateandwhenthereactionisreversedtheenergyyouputintotheMgSO4withyourBunsenburnerwillnowbereleasedinanexothermicreaction. ScenarioInthislabwewilldissolveMagnesiumSulfatehydrate(MgSO47H2O)andmagnesiumsulfateanhydrate(MgSO4)tofindtheΔHvaluesforeachprocess.Ahydrateisachemicalwithwatertrappedinitscrystallinestructure.Whenyoulookatthehydrateyouwillnoticeitlooksdry,notwet.Thatisbecausethewateristrapped.Weuseadotintheformulaofahydratetoshowthatthewatermoleculesaretrapped.InordertofindtheΔH(enthalpyofhydration)wewillperformtwoseparateexperiments,andthenrelatethemtofindourgoalreaction.Reaction1:MgSO4(s)Mg+2(aq)+SO4‐2(aq)Herewewilladdwatertotheanhydratetodissolvethesubstance.Reaction2:MgSO47H2O(s)Mg+2(aq)+SO4‐2(aq)+7H2O(l)Herewewilldissolvethehydratedcrystalinwater.GoalReaction:MgSO4(s)+7H2O(l)MgSO47H2O(s)ByaddingtheabovereactionstogetherwecandeterminetheΔHforthisreaction.
H2O
H2O
Name(s): Period: Date:
H2O
HASPIMedicalChemistryUnit6:Energy Lab6b,Page8
UsingHess'lawyoucanreversethesecondreactionandaddittothefirstinordertocalculatetheΔHofthegoalreaction.FirstwewillcalculatetheΔHforreaction1andreaction2usingcalorimetry.ProcedureandcalculationsforReaction1:MgSO4(s)Mg+2(aq)+SO4‐2(aq)1.ObtainasampleoftheanhydrousMgSO4.WeighthesampleandrecordthemassinDataTable1.Itshouldbeabout1.50‐3.00g.2.Addexactly20.0mLofDIwatertoyourcalorimeter.3.Recordtheinitialtemperatureofthewater.4.AddtheMgSO4anhydratetoyourcalorimeterandimmediatelyclosethelid.5.Stiruntilthetemperaturestopsincreasing.6.Recordthehighesttemperaturereachedasthefinaltemperature.
DATATABLE1MassofanhydrousMgSO4pelletorpowder
Massofwaterused(sameasmL)
Initialtemperatureofthewater
FinalTemperatureofthewater
ΔT(Final‐Initial)
CalculationsforReaction11.Useq=mcΔTtofindouthowmanyjoulesofenergywereabsorbedbythewater.Rememberthatthespecificheatofwateris4.184J/g°C.Besuretousethemassofwaterforthiscalculation.(Forwater1mL=1g)
a)EnergyinJoulesb)EnergyinkJ
2.Findthemolesofanhydrateuseda.WhatisthemolarmassofMgSO4?b.ConvertthegramsofMgSO4inDataTable1intomoles
a)molarmassofMgSO4
b)molesofMgSO4used
3.FindthejoulesofheatreleasedfromthereactioninkJ.Remember,energyabsorbedbywaterisnegativetheenergyreleasedfromthereaction.
Energy=
4.FindtheΔHforthisreactioninkJ/mol.(dividekJbymoles)
ΔH1=
5.Isthisreactionendothermicorexothermic?
H2O
HASPIMedicalChemistryUnit6:Energy Lab6b, Page9
ProcedureandcalculationsforReaction2: MgSO47H2O(s)Mg+2(aq)+SO4‐2(aq)+H2O(l ) 1.Weighoutabout2.00gofcrystalline MgSO47H2O 2.Addexactly20.0mLofDIwatertoyourcalorimeter3.Recordtheinitialtemperatureofthewater4.AddtheMgSO4hydratedcrystalstoyourcalorimeterandimmediatelyclosethelid5.Stiruntilthetemperaturestopsincreasing6.Recordthefinaltemperaturereachedbythesolutionafteritstopschanging
DATATABLE2
MassofMgSO47H2O
Massofwaterused(sameasmL)
Initialtemperatureofthewater
FinalTemperatureofthewater
ΔT(Final‐Initial)
CalculationsforReaction21.Useq=mcΔTtofindouthowmanyjoulesofenergywereabsorbedbythewater.Rememberthatthespecificheatofwateris4.184J/g°C.Besuretousethemassofwaterforthiscalculation.(Forwater1mL=1g)
a)answerinJoulesb)answerinkJ
2. Find the moles of anhydrate used a. What is the molar mass of MgSO47H2O? b. Convert the grams of MgSO47H2O in Data Table 2 into moles
a) molar mass of MgSO7H2O4
b) moles of MgSO47H2O used
3. Find the joules of heat absorbed in the reaction in kJ. Remember, energy lost by water is negative the energy gained by the reaction.
Energy=
4. Find the ΔH for this reaction in kJ/mol. (divide kJ by moles)
ΔH2 =
5. Is this reaction endothermic or exothermic?
H2O
HASPIMedicalChemistryUnit6:Energy Lab6b,Page10
Conclusions: Calculate the ΔH for the goal reaction using the given reactions 1. Label each reaction with the enthalpy of reaction you found in the lab Reaction 1: MgSO4(s) Mg+2(aq) + SO4-2(aq) ΔH1 = Reaction 2: MgSO47H2O (s) Mg+2(aq) + SO4-2(aq) + 7H2O(l) ΔH2 =
2. In order to find the goal reaction, the above reactions may be reversed or multiplied as needed so that they add up to make this reaction: MgSO4(s) + 7H2O(l) MgSO47H2O (s) Remember that a reversed reaction causes the sign on the ΔH value to reverse, and a doubled reaction doubles the ΔH value. Cancel out anything that appears on both sides of the arrows. Show your work as you add these reactions together: Reaction 1: ΔH = + Reaction 2: ΔH = Equals Goal Reaction MgSO4(s) + 7H2O(l) MgSO47H2O (s) ΔH = 3. When you add together the ΔH values, what is the ΔH of hydration for MgSO4? 4. If the theoretical value is -104kJ/mol, what is the percent error? 5. List 2 sources of unavoidable error
H2O
H2O
HASPIMedicalChemistryUnit6:Energy Lab6b, Page11
Applications:
1.Explainthedifferencebetweenpotentialenergyandkineticenergyin2‐3sentences.
2.Usingthetermspotentialandkineticenergy,describewhathappenedinthefirstreaction,whereyoudissolvedtheanhydrateinwater.
3.Thelawofconservationofenergystatesthatthetotalenergyofanisolatedsystemcannotchange.Howdoesthisapplytoourlab?4.Whatcouldyoudotoincreasetheamountofenergyreleasedinreaction1?5.Attheendofthetrial,thetemperaturebegantodecrease.Whathappenedtotheenergythatwasinthecalorimeter?
6.Whatchangescouldyouhavemadetothelabapparatustoimproveyourresults,reducingyourpercenterror?
HASPIMedicalChemistryUnit6:Energy Lab6b,Page12
7.Drawadiagramofeachexperiment,includingthecalorimeter,thechemicalandthewater.Usearrowstoshowtheflowofenergybetweenthemagnesiumsulfateandthewater.Experiment1:DissolvingtheAnhydrate
Experiment2:DissolvingtheHydrate
ResourcesandReferenceshttp://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=1&ContentID=4483http://www.spine‐health.com/treatment/heat‐therapy‐cold‐therapy/benefits‐heat‐therapy‐lower‐back‐painhttp://www.middleschoolchemistry.com/lessonplans/chapter5/lesson9http://home.howstuffworks.com/question290.htmhttp://prezi.com/lranljsxv4hx/copy‐of‐chemistry‐hotcold‐packs/Pictures:http://www.chemistryland.com/CHM130FieldLab/Lab11/Lab11.html