ChemistryFinalExamReview
1. Defineamole.Whatdoesittellusabouta
substance?
2. Determinethemolarmassforcalciumacetate–
Ca(C2H3O2)2.
3. Forsodiumsulfate(Na2SO4),calculatethepercent
compositionofsodium.
4. Howmanymolesarein30gofNaCl?
THEMOLE
□Defineamoleanddescribewhatittellsabout
asubstance.
□Beabletodeterminethemolarmassofa
substance
□Beabletodeterminethepercentcomposition
bymassofelementsincompound.
□Beabletoconvertbetweenunitsusingthe
followingconversionfactors:
1mole=molarmassingrams=22.4Lofagas
atSTP
□Beabletodefineempiricalandmolecular
formulas.
5. Howmanygramsarein3.00molesofKCl?
6. Defineempiricalformula.
7. Definemolecularformula.
8. Howdoyoudeterminetheempiricalformulafromthemolecularformula?
9. Determinetheempiricalformulaofthefollowingmolecularformulas:
• C6H12O6
• C25H50O5
10. Howmuchwould100LofwatervaporweighingramsatSTP?
•
C 6 H6 1.
Balancethefollowingequations:
NaCl+Ca→CaCl2+Na
Sn(CO3)2+K→K2(CO3)+Sn
NaOH+AlPO4→Na3PO4+Al(OH)3
FeO+Al→Al2O3+Fe
Al2O3+Mg→MgO+Al
C2H4+O2→CO2+H2O
2.
3.
Na+Cl2→NaCl
StatetheLawofConservationofMass.
Whatdoesthelawofconservationofmass
meanforusinchemistry?
CHEMICALREACTIONS
□Knowwhatindicatesthatachemicalreactionhastaken
place:temperaturechange,colorchange,formationofa
gas(bubbles),andformationofaprecipitant(solidis
formedwhentwoliquidsreact)
□Knowthatthereactantsareontheleftandtheproducts
areontheright.
□Knowhowtobalancetheequationbyaddingcoefficients
untilthenumbersofatomsareequaloneachside.
□Knowhowtoproperlyusesubscriptstocountelements.
Forexample,Al2(SO4)3meansthereare2Al’s,3S’sand12
O’s.
□Knowhowtoproperlyusecoefficientstocountelements.
Forexample,3Al2(SO4)3meansthereare6Al’s,9S’sand36
O’s.
□Knowthatabalancedequationisaconfirmationofthe
lawofconservationofmass
--------------------------------------------------------------------------------------------------------------------------------------------------
STOICHIOMETRY
1. Giventhefollowingreaction:H2O2→H2+
□Knowthestepsforsolvingallstoichiometry
O2,howmanymolesofH2willyoumakeifyou
problems.
beginwith2.51molesofH2O2?
a. Balancedequation.Knowthatthe
coefficientsforeachcompoundrepresent
theratioofmolesintheequation.
b. Setupyourproportionwiththeknown
andunknownontop,stacklikeunitswith
theconversionfactors.
2. Giventhefollowingreaction:2ZnS+3O2→
□Knowhowtocalculatethemolarmassofa
2ZnO+2SO2,howmanymolesofZnOwillyou
compound.Addupthemolarmassforeachelement.
makeifyoubeginwith6.82gramsofO2?
Multiplybyacoefficient.
□Knowhowtocalculateareaction’spercentyield.
%yield=actualyield/theoreticalyield
□Beabletodefinelimitingreactant,excessreactant,
actualyield,theoreticalyield
3. Giventhefollowingreaction:2ZnS+3O2→2ZnO+2SO2,howmanymolesofZnOwillyoumakeif
youbeginwith55.75gramsofO2?
4. Inthefollowingreaction:H2CO3(aq)+2Na(s)→Na2CO3(aq)+H2(g),howmanygramsofNaare
needtomake5.0gramsofH2?
5. Fromtheproblemabove,whatisthepercentyieldofNaifonly105gramsaremade?
6. Definethefollowingterms:
a. stoichiometry
b. limitingreactant
c. excessreactant
d. actualyield
e. theoreticalyield
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1. Describethedifferencesbetweentheparticlesinasolid,liquid,andgas.
2. Whatdoestemperaturetellusaboutasubstance?
3. Describetherelationshipbetweenthefollowingvariables:
a) Pressureandnumberofcollisions
b) Temperatureandpressure
c) Volumeandpressure
d) Temperatureandvolume
4. Ifthepressureofagaschangesfrom4.5
atmto3.75atm,whatwastheoriginal
volumeifthefinalvolumewas7.55L?
5. Agasat30oCand3.4atmpressureisput
underapressureof3.0atm.Whatisthe
newtemperature?
GASLAWS
□KnowhowtousetheGasLaws.TheGasLawswillbe
giventoyou.
□Knowhowinverserelationshipswork.(Ifonepartis
increased5times,theotherpartwilldecreaseto1/5.)
Ex.Pressurevs.volume
□Knowhowdirectrelationshipswork.(Ifonepartis
increased5times,theotherpartwillincrease5times.)
Ex.Pressurevs.TempandVolumevs.Temp
□KnowthatSTPisstandardtemperatureandpressure.
Standardtemperatureis0Candstandardpressureis1
atmosphere.
6. Twogaseswiththepressureof1.5atm
eachareplacedintoagastank.Whatis
thetotalpressureinthetank?
□KnowAvogadro’sprinciple–conceptuallyand
mathematically.
□Knowhowtoconvertmolesofagastolitersorlitersto
molesusing22.4L/1mole.
□BeabletosolvegasstoichiometryproblemsatSTP.
7. AgasatSTPoccupies2.5L.Whatvolume
willitoccupyifthetemperatureis
changedto300Kandthepressure
changesto1.25atm?
□Knowthatpressureiscausedbythenumberofparticles
hittingthesidesofacontainer.Knowwhatcanchange
thepressurewithinacontainer.
□KnowhowtoconvertoCtoKorKtooC.
□Knowthatallgaslawproblemsaresolvedusingthe
Kelvintemperaturescale.
□Beabletodefinediffusionvs.effusion
□Knowthepostulatesofthekineticmoleculartheory
8. Giventhefollowingreaction:2ZnS+3
O2→2ZnO+2SO2,howmanylitersof
O2areneededatSTPtoform7.5LofSO2?
□Beabletocomparethepropertiesandparticle
behaviorsofsolids,liquids,andgases.
9. Inthefollowingreaction:H2CO3(aq)+2Na(s)→Na2CO3(aq)+H2(g),howmanylitersofhyrdrogen
gasareproducedatSTPifyoumake12.45molesofNa2CO3?
SOLUTIONS
□Knowthatsolutionsaremadeupoftwoparts–thesolventandthesolute.
□Thesolventisusuallywateranditmakesupthemajorityofthesolution.
□Thesoluteiswhatisbeingdissolvedanditmakesupthesmallerportionofthesolution.
□Beabletodescribethetrendsinsolubilityastemperatureincreasesforasolidinwaterandagasinwater.
□KnowhowtointerpretaSolubilityGraphanddetermineifasolutionissupersaturated,unsaturated,or
saturated.
□Defineanddescribethedifferencesbetweenasaturated,unsaturated,andsupersaturatedsolution.
□Knowhowtospeedupthedissolvingofasolute.
□Knowwhatitmeanstodiluteasolutionandhowtocalculateit.
Grams of Solute Dissolved
Solubility (grams of solute/100 g of water)
300
250
KNO3
200
NaNO3
150
LiCl
100
KCl
50
0
0
20
40
60
Temperature (oC)
80
100
SOLUTIONS(cont.)
□Knowthat“likedissolveslike”whichmeanspolar
substanceswilldissolvepolarsubstancesandnonpolarsubstanceswilldissolvenon-polarsubstances.
Theywillnotdissolveeachother.
□Knowthatwemeasureasolution’sconcentrationby
measuringthenumberofmolesdissolvedin1L.
(molarity)
□Knowhowtodeterminemolaritywhengivenmoles
andvolumeorwhengivengramsandvolume
□Knowhowtodeterminevolumewhengivenmoles
Usethegraphabovetoanswer#1-3.
andmolarity.
1. Howmanygramsareneededtomakeasaturated
o
□Knowhowtodeterminemoleswhengivenvolume
solutionofKNO3at50 C?
andmolarity.
□Beabletodefineanelectrolyte
2. At60oC,whattypeofsolutionwillyouhaveif70
gramsofKClaredissolvedin100gofwater?
3. If100gramsofNaNO3aredissolvedin100gramsofwater,whatmustthetemperaturebetomakeita
saturatedsolution?
4. Calculatethemolarityofasolutionofsodiumcarbonateif2.35molesaredissolvedinenoughwaterto
make1.2Lofsolution.
5. Howmanymolesareneededtoprepare0.252Lofa0.3Msolutionofaluminumoxide?
6. Whatdoesitmeantodiluteasolution?Howwouldyoudiluteit?
7. IfIhave340mLofa0.5MNaBrsolution,whatwilltheconcentrationbeifIadd560mLmorewatertoit?
8. Ifyouwantedtodissolvesugarintowater,whatstepscouldyoutaketomakeitgofaster?
9. Whichofthefollowingwouldmostlikelydissolveinwater?Justifyyouranswer.Carbontetrafluoride
(nonpolar)orammonia(polar).
10. Whichofthefollowingwouldmostlikelyconductelectricityinsolution?Justifyyouranswer.CCl4or
NaHCO3.
--------------------------------------------------------------------------------------------------------------------------------------------------
1. DeterminethepHofa0.2Msolutionofhydrochloric
AcidsandBases
acid?
□Beabletodefinestrongacids/bases.
□KnowhowtocalculatethepH.
□Beabletodetermineifasubstanceisacidicor
basicbasedonpH.
-6
□Beabletodescribethepropertiesofacidsand 2. DeterminethepHofa4.37x10 Msolutionofnitric
acid?
bases:howtheyaffectlitmuspaper,theirtaste,
pHrange,ionspresent.
□Defineaneutralizationreactionanddetermine theproductsinthesereactions
3. Whatmakesanacid/basestrongversusweak?
4. Whatarethepropertiesofacids?
5. Whatarethepropertiesofbases?
6. Whatisformedwhenyoumixanacidandbase?
---------------------------------------------------------------------------------------------------------------------------------------
1. Defineanendothermicreaction.Giveanexample.
Thermochemistry
□Beabletodescribethedifferencebetween
anexothermicandendothermicprocessby
definition.
2. Defineanexothermicreaction.Giveanexample.
□Beabletocalculatespecificheatof
substances
□Beabletodefinespecificheatofasubstance
□Beabletosketchandlabelaheatingcurve.
3. Definespecificheat.
4. Whatwouldbethedifferencebetweenheatingasubstancewithalowspecificheatandahighspecific
heat?
5. Whatisthespecificheatofasubstancethatabsorbs25Jofheatandhasachangeintemperaturefrom
20Cto26C?
6. Sketchandlabelthestatesofmatterandphasechangesintheheatingcurveofconvertingiceto
steam.