Treść książki
Przejdź do opcji czytnikaPrzejdź do nawigacjiPrzejdź do informacjiPrzejdź do stopki
UsecurrentintensitiesshowninTable1.1.Aftereachchangeofthecurrentintensity,
waitaminutetostabilizethepotentialvalueandreadtheelectrodepotential.Noteresultsin
Table1.1,individuallyforeachelectrode.
Calculationsanddiscussionofresults
1.Valuesofelectrodepotentialsmeasuredvs.SCEcalculatevs.standardhydrogenelectrode
SHE.TheSCEpotentialvs.SHEis:
E
o,SCE=241.5-0.76(tO-25)mV
wheretO-temperature,OC.
(1.16)
2.Plottheexperimentaldataforeachelectrodeasthefollowingdependences:i=f(E
i)and
E
i=f(logi).
3.Discusstheinfluenceof:
a)currentdensity,
b)concentrationoftheelectroactivespecies,
c)agitationoftheelectrolyte
onthetypeofelectrodepolarizationandoverpotentialvalues.
4.Usingtheexperimental(Tab.1.1)andliterature(Tab.1.2)dataplotpolarizationcurves
I=f(E
i).Tocalculatenecessaryvalues,choosesuitablegalvaniccells.Writeanodicand
cathodicreactionstakingplaceintheselectedgalvaniccells.
Note:ThevaluesofcurrentdensityshowninTable1.2shouldbeconvertedintocurrent
intensity.Usethesameareaoftheelectrodeasfortheexperimentalworkingelectrode.
Examplesofgalvaniccells:
Zn/1MZnSO
4//0.5MCuSO
4/Cu,
Zn/1MZnSO
Zn/1MZnSO
4//1MH
4//1MH
2SO
2SO
4/Pt,
4/Fe,
Pt/1MH
2SO
4//0.5MCuSO
4/Cu.
5.Determinevaluesofshort-circuitcurrentsforselectedgalvaniccellsfromtheplots
(Fig.1.6)andtheequation(1.14).Ifanodicandcathodicpolarizationcurvesareunable
tointersectinaplot(inadequateaxisscale),drawthecurvesasE
i=f(logi)andthen
findthedensityofshort-circuitcurrentcorrespondingtothecorrosioncurrent.
6.Usingtheexperimentalresultsandliteraturedata(Tab.1.2)calculatethevoltagetobe
appliedtogetacertaincurrentinthefollowingelectrolysissystems:
a)Cu/0.5MCuSO
b)Cu/0.5MCuSO
4/Cu,
4/Pb,
c)Zn/1MZnSO
4/1MH
2SO
4/Pb,
d)Zn/1MZnSO
4/1MH
2SO
4/Fe,
e)Zn/1MZnSO
4/1MH
2SO
4/Pt,
Assume:R
E=0ΩandR
I=10Ω.
Writeanodicandcathodicreactionsfortheindividualelectrolysisprocesses.
19
