Chemistry12

ElectrochemistryPracticeTestName:Date:Block:

I. MultipleChoice______1.Whenanelectrodelosesmass,italso:

A. loseselectrons B. actsasanoxidizingagentC. becomesreducedD. decreasesinoxidationnumber

______2.Atstandardconditions,Fe+2reactsspontaneouslywith

A. I2B. Br-C. CoD. Ag+

3.Explainyouranswertothequestionabove:______4.Whichofthefollowinghalf-reactionsisbalanced?

A. SO4-2+H2OàSO3-2+2H++2e-B. SO4-2+H2O+2e-àSO3-2+2H+ C. SO4-2+2H++2e-àSO3-2+H2OD. SO4-2+2H+àSO3-2+H2O+2e-

______5.Duringaredoxreaction,theoxidizingagent:

A. reducesotherspecies B. increasesinoxidationnumberC. gainselectrons D. becomesoxidized

______6.Foragivenredoxrxn,theoxidation#oftinchangedfrom+2to+4.Asaresult,tin:

A. lost2electronsandwasreducedB. gained2electronsandwasreduced C. lost2electronsandwasoxidizedD. gained2electronsandwasoxidized

______7.Inwhichofthefollowingcompoundsdoescarbonhaveanoxidationnumberof-2?

A. COB. CH2OC. CO2D. CH3OH

______8.Whichofthefollowingequationsrepresentsaredoxreaction?

A. ZnCl2àZn2++2Cl-B. Zn+Br2àZnBr2C. H2CO3àH2O+CO2D. 2NaI+Pb(NO3)2àPbI2+NaNO3

______9.Considerthefollowingreaction: SO4-2+8I-+8H+àS-2+2I2+4H2OThereducingagentis

A. I- B. SinSO42-C. H+ D. OinSO42-

______10.WhenMnO4-2undergoesoxidation,itmayform:

A. MnO B. MnO3C. MnO4- D. Mn2O3

11.Explainyouranswertothequestionabove:______12.Considerthefollowingreaction:

3I2+3H2Oà6H++5I-+IO3-Inthisreaction,theI2atomsundergo:

A. oxidationonly B. bothoxidationandreductionC. reductiononly D. neitheroxidationnorreduction

______13.Inanelectrochemicalcell,electronsflowfromthe

A. anodetothecathodethroughthesaltbridge B. anodetocathodethroughtheexternalcircuitC. cathodetotheanodethroughthesaltbridge D. cathodetoanodethroughtheexternalcircuit

14.Explainyouranswertothequestionabove:______15.Whenmoltenaluminumoxideiselectrolyzed,thecathodereactionis:

A. AlàAl3++3e-B. Al3++3e-àAlC. O2+4eà2O2-D. 2O2-àO2+4e-

______16.Goldisfoundinnatureinitspureformbecause:

A. Au3+isastrongreducingagent B. Au3+astrongoxidizingagentC. AuisastrongreducingagentD. Auisastrongoxidizingagent

17.Explainyouranswertothequestionabove:______18.TheelectrolysisofNa2SO4(aq)wouldproducethisgasattheanode.

A. OxygenB. HydrogenC. WatervapourD. Sulfurdioxide

Usethefollowingcelldiagramforquestions19and20.

________19.Intheaboveelectrochemicalcell,A.themassoftheanodeincreasesandthemassofthecathodeincreases.B.themassoftheanodedecreasesandthemassofthecathodedecreases.C.themassoftheanodedecreasesandthemassofthecathodeincreases.D.themassoftheanodeincreasesandthemassofthecathodedecreases.

________20.Intheaboveelectrochemicalcell,A. TheanodeisZnandthecathodeisCuB. TheanodeisCuandthecathodeisZnC. TheanodeisZn2+andthecathodeisCu2+D. TheanodeisCu2+andthecathodeisZn2+

________21.Intheoperatingelectrochemicalcellabove,thevoltageproducedis:

A.-1.10V C.0.00VB.-0.42V D.+1.10V

22.Explainyouranswertothequestionabove:

II.Problems1)Foreachofthefollowingcompounds,identifytheoxidationnumberoftheatom(s)indicated.a)Mg2TiO4 Mg= Ti= O=

b)K2Cr2O7 K= Cr= O=

c)MnO4- Mn= O=

2)AMn/Mn2+andAg+/Agelectrochemicalcellissetupatstandardconditions.Drawtheelectrochemicalcellforthisparticularreaction.Labelallpartsofthecell,includingthevoltageproduced.

3)Balancethefollowingredoxreactions.

a) Mn+2+BiO3-àMnO4-+Bi+3(acidic)

a) Sb2S3+NO3-àNO2+SO42-+Sb2O5(basic)

4)Youhavebeengiventhefollowingfivehalf-reactions:A2++2e-àAB2++2e-àBC2++2e-àCD2++2e-àDE2++2e-àE

• B2+reactedwithA.• E2+didnotreactwithC.• D2+onlyreactedwithBandA.Giventheaboveinformation,createanSRPtable:

5)Foreachofthefollowing,drawtheelectrolyticcell,includingthehalf-reactionsoccurringwithinit:

a) PlatinumelectrodesinmoltenMgBr2

b) CopperelectrodesinNaCl(aq)