INSTRUMENTAL ANALYSIS FINAL
EXAM REVIEW QUESTIONS AND
CORRECT ANSWERS
whichA2ofA2theA2followingA2moleculesA2canA2haveA2anA2nA2toA2sigma*A2absorptionA2-
A2Ans--bothA2NH3A2andA2H2OA2dueA2toA2presenceA2ofA2loneA2pairsA2(n)
anA2unknownA2compoundA2hasA2anA2absorptionA2atA2600A2nmA2inA2water,A2620A2nmA2inA2
methanolA2(CH3OH),A2andA2640A2nmA2inA2decane.A2WeA2sayA2thereA2isA2aA2___A2shiftA2inA
2theA2wavelengthA2onA2goingA2toA2moreA2polarA2solventsA2-A2Ans--hypsochromic
givenA2theA2followingA2absorptionA2spectraA2ofA2aA21.5A2xA210^-
4A2MA2organicA2sampleA2inA2aA21A2cmA2pathlengthA2cell,A2theA2absorptionA2isA2mostA2likely
A2fromA2whatA2typeA2ofA2transition?A2-A2Ans--
piA2toA2pi*A2(approximatelyA2650A2nmA2peakA2withA2absorbanceA2ofA21A2inA2water,A2approx
imatelyA2600A2nmA2peakA2withA2absorbanceA2ofA21A2inA2hexane)
givenA2theA2followingA2absorptionA2spectrumA2ofA2aA20.001A2MA2organicA2sampleA2inA2aA22
A2cmA2pathlengthA2cell,A2theA2absorptionA2isA2mostA2likelyA2fromA2whatA2typeA2ofA2transitio
n?A2-A2Ans--nA2toA2sigma*A2(absorbanceA2aroundA2200A2nmA2withA2intensityA21)
assumeA2youA2haveA2anA2octahedralA2complexA2ofA2aA2metalA2atomA2containingA2dA2orbit
alsA2andA2CN-.A2theA2complexA2absorbsA2atA25ooA2nm.A2theA2CN-
A2ligandsA2interactA2mostA2withA2whichA2orbitals?A2-A2Ans--bothA2dz^2A2andA2dx^2-y^2
assumeA2youA2haveA2anA2octahedralA2complexA2ofA2aA2metalA2atomA2containingA2dA2orbit
alsA2andA2CN-.A2theA2complexA2absorbsA2atA2500A2nm.A2ifA2theA2CN-
A2ligandsA2wereA2replacedA2withA2NH3A2ligands,A2d:A2I-<Br-<Cl-<F-<OH-
<H2O<NH3<NO2-<CN-A2-A2Ans--theA2absorptionA2wavelengthA2increases
shimadzuA2doubleA2beamA2spectrometerA2measuresA2lightA2comingA2throughA2theA2sampl
eA2cellA2containingA2solventA2andA2analyteA2(Psample),A2aA2referenceA2cellA2containingA2o
nlyA2theA2solventA2(Pblank),A2andA2signalA2whenA2noA2lightA2fallsA2onA2theA2detectorA2(Pda
rk).A2whichA2expressionA2bestA2representsA2theA2absorbanceA2ofA2theA2analyte?A2-A2Ans---
log[(Psolution-Pdark)/(Pblank-Pdark)]
whichA2photometricA2curveA2couldA2beA2fromA2theA2titrationA2ofA2aA2non-
absorbingA2sampleA2withA2anA2absorbingA2titrantA2toA2obtainA2aA2non-absorbingA2product?
A2-A2Ans--A.A2noA2absorbanceA2andA2thenA2linearA2increase
theA2shimadzuA2doubleA2beamA2spectrometerA2usesA2anA2opticalA2chopperA2toA2helpA2-
A2Ans--performA2signalA2averagingA2andA2correctA2forA2darkA2current
,electronicallyA2excitedA2singletA2statesA2typicallyA2haveA2aA2lifetimeA2ofA2approxiatelyA2-
A2Ans--10^-9A2s
whichA2ofA2theA2followingA2moleculesA2canA2haveA2anA2nA2toA2pi*A2absorption?A2-A2Ans--
CH3-COOH
absorptionsA2inA2theA2UV-
VisA2regionA2ofA2theA2spectrumA2resultA2fromA2theA2excitationA2ofA2___A2energyA2levelsA2-
A2Ans--electronic
forA2theA2absorptionA2ofA2aA2UVA2orA2VisA2photonA2byA2aA2molecule,A2theA2energyA2ofA2theA
2photonA2mustA2beA2___A2theA2energyA2differenceA2betweenA2twoA2levelsA2inA2theA2molec
uleA2-A2Ans--equalA2to
whatA2isA2theA2purposeA2ofA2aA2filterA2wheelA2onA2aA2spectrometerA2withA2aA2gratingA2mon
ochromator?A2-A2Ans--removeA2higherA2orderA2spectraA2comingA2offA2theA2grating
anA2organicA2moleculeA2hasA2aA2lamdamaxA2=A2600A2nmA2andA2aA2molarA2absorptivityA2=A
22000A2M^-1A2cm^-1.A2whatA2typesA2ofA2bondsA2mustA2theA2moleculeA2have?A2-A2Ans--pi
describeA2howA2youA2mightA2performA2aA2photometricA2titrationA2whenA2theA2sample,A2titra
nt,A2andA2productA2allA2absorbA2lightA2-A2Ans--
findA2threeA2wavelengthsA2whereA2theA2sample,A2product,A2andA2titrantA2absorb.A2measur
eA2theA2nineA2molarA2absorptivitiesA2forA2standardsA2ofA2theA2sample,A2product,A2andA2titra
nt.A2measureA2atA2threeA2wavelengthsA2asA2aA2functionA2ofA2titrantA2volumeA2added.A2solv
eA2theA2threeA2simultaneousA2equationsA2forA2theA2concentrationA2ofA2titrant,A2sample,A2a
ndA2product
aA2materialA2containingA2whichA2typeA2ofA2absorptionA2wouldA2makeA2theA2bestA2ink?A2-
A2Ans--chargeA2transfer
aA2materialA2withA2whichA2typeA2ofA2absorptionA2(only)A2wouldA2makeA2aA2goodA2invisibleA
2ink?A2-A2Ans--nA2toA2sigma*
beA2ableA2toA2determineA2eachA2pieceA2ofA2fluorescenceA2diagramA2-A2Ans--
fluorescenceA2(1),A2phosphorescenceA2(9),A2absorptionA2(6),A2predissociationA2(10),A2diss
ociationA2(3),A2intersystemA2crossingA2(7),A2internalA2conversionA2(2),A2externalA2conversi
onA2(5),A2vibrationalA2relaxationA2(4)
youA2areA2measuringA2theA2fluorescenceA2intensityA2fromA2S2A2toA2S0A2forA2aA2moleculeA2
withA2theA2aboveA2diagramA2byA2excitingA2theA2moleculeA2inA2solutionA2fromA2S0A2toA2S3.A
2WhatA2willA2theA2followingA2changesA2doA2toA2theA2fluorescenceA2intensityA2fromA2S2A2toA
2S0?A2HeatingA2theA2solutionA2-A2Ans--decrease
coolingA2theA2solution?A2-A2Ans--increase
, bubbleA2theA2solutionA2withA2O2?A2-A2Ans--remainA2theA2same
bubblingA2theA2solutionA2withA2N2?A2-A2Ans--remainA2theA2same
changeA2theA2excitationA2wavelengthA2toA2correspondA2toA2theA2energyA2ofA2theA2S0A2toA2
S2A2transition?A2-A2Ans--increase
changeA2theA2excitationA2wavelengthA2toA2correspondA2toA2theA2energyA2ofA2theA2S0A2toA2
S1A2transition?A2-A2Ans--decrease
placeA2theA2moleculeA2inA2aA2lessA2viscousA2solventA2-A2Ans--decrease
theA2lifetimeA2ofA2anA2excitedA2tripletA2stateA2canA2beA2asA2longA2as?A2-A2Ans--minutes
theA2purposeA2ofA2theA2referenceA2photomultiplierA2onA2aA2spectrofluorimeterA2isA2toA2-
A2Ans--correctA2forA2variationsA2inA2xenonA2lampA2intensity
givenA2theA2followingA2absorptionA2spectraA2ofA2aA21.5A2xA210^-
4A2MA2organicA2sampleA2inA2aA21A2cmA2pathlengthA2cell,A2theA2absorptionA2isA2mostA2likely
A2fromA2whatA2typeA2ofA2transition?A2-A2Ans--
fluorescenceA2alwaysA2occursA2atA2anA2equalA2orA2smallerA2___A2toA2thatA2ofA2theA2photon
A2absorbed?A2-A2Ans--frequency
withA2anA2emissionA2spectrumA2onA2aA2fluorescenceA2spectrometer,A2theA2excitationA2wav
elengthA2isA2-A2Ans--fixedA2andA2theA2emissionA2wavelengthA2varied
whatA2isA2theA2purposeA2ofA2aA2filterA2wheelA2onA2aA2fluorimeter?A2-A2Ans--
removeA2higherA2orderA2spectraA2fromA2theA2grating
aA2moleculeA2hasA2aA2singletA2groundA2stateA2andA2hasA2theA2followingA2absorption,A2fluor
escence,A2andA2phosphorescenceA2spectra.A2predictA2theA2energyA2levelA2diagramA2ofA2t
heA2moleculeA2-A2Ans--A
inA2aA2fluorescenceA2spectrum,A2theA2fluorescenceA2intensityA2isA2proportionalA2toA2___A2
whereA2C=concentrationA2-A2Ans--C
whichA2ofA2theA2followingA2moleculesA2isA2moreA2likelyA2toA2fluoresce?A2-A2Ans--
naphthaleneA2(notA2sucrose)
atomicA2energyA2levelA2diagramsA2willA2notA2displayA2-A2Ans--vibrationalA2energyA2levels
whatA2isA2theA2approximateA2ionizationA2ofA2NaA2inA2eVA2-A2Ans--
5.2A2(labelledA2asA2suchA2onA2diagram)
EXAM REVIEW QUESTIONS AND
CORRECT ANSWERS
whichA2ofA2theA2followingA2moleculesA2canA2haveA2anA2nA2toA2sigma*A2absorptionA2-
A2Ans--bothA2NH3A2andA2H2OA2dueA2toA2presenceA2ofA2loneA2pairsA2(n)
anA2unknownA2compoundA2hasA2anA2absorptionA2atA2600A2nmA2inA2water,A2620A2nmA2inA2
methanolA2(CH3OH),A2andA2640A2nmA2inA2decane.A2WeA2sayA2thereA2isA2aA2___A2shiftA2inA
2theA2wavelengthA2onA2goingA2toA2moreA2polarA2solventsA2-A2Ans--hypsochromic
givenA2theA2followingA2absorptionA2spectraA2ofA2aA21.5A2xA210^-
4A2MA2organicA2sampleA2inA2aA21A2cmA2pathlengthA2cell,A2theA2absorptionA2isA2mostA2likely
A2fromA2whatA2typeA2ofA2transition?A2-A2Ans--
piA2toA2pi*A2(approximatelyA2650A2nmA2peakA2withA2absorbanceA2ofA21A2inA2water,A2approx
imatelyA2600A2nmA2peakA2withA2absorbanceA2ofA21A2inA2hexane)
givenA2theA2followingA2absorptionA2spectrumA2ofA2aA20.001A2MA2organicA2sampleA2inA2aA22
A2cmA2pathlengthA2cell,A2theA2absorptionA2isA2mostA2likelyA2fromA2whatA2typeA2ofA2transitio
n?A2-A2Ans--nA2toA2sigma*A2(absorbanceA2aroundA2200A2nmA2withA2intensityA21)
assumeA2youA2haveA2anA2octahedralA2complexA2ofA2aA2metalA2atomA2containingA2dA2orbit
alsA2andA2CN-.A2theA2complexA2absorbsA2atA25ooA2nm.A2theA2CN-
A2ligandsA2interactA2mostA2withA2whichA2orbitals?A2-A2Ans--bothA2dz^2A2andA2dx^2-y^2
assumeA2youA2haveA2anA2octahedralA2complexA2ofA2aA2metalA2atomA2containingA2dA2orbit
alsA2andA2CN-.A2theA2complexA2absorbsA2atA2500A2nm.A2ifA2theA2CN-
A2ligandsA2wereA2replacedA2withA2NH3A2ligands,A2d:A2I-<Br-<Cl-<F-<OH-
<H2O<NH3<NO2-<CN-A2-A2Ans--theA2absorptionA2wavelengthA2increases
shimadzuA2doubleA2beamA2spectrometerA2measuresA2lightA2comingA2throughA2theA2sampl
eA2cellA2containingA2solventA2andA2analyteA2(Psample),A2aA2referenceA2cellA2containingA2o
nlyA2theA2solventA2(Pblank),A2andA2signalA2whenA2noA2lightA2fallsA2onA2theA2detectorA2(Pda
rk).A2whichA2expressionA2bestA2representsA2theA2absorbanceA2ofA2theA2analyte?A2-A2Ans---
log[(Psolution-Pdark)/(Pblank-Pdark)]
whichA2photometricA2curveA2couldA2beA2fromA2theA2titrationA2ofA2aA2non-
absorbingA2sampleA2withA2anA2absorbingA2titrantA2toA2obtainA2aA2non-absorbingA2product?
A2-A2Ans--A.A2noA2absorbanceA2andA2thenA2linearA2increase
theA2shimadzuA2doubleA2beamA2spectrometerA2usesA2anA2opticalA2chopperA2toA2helpA2-
A2Ans--performA2signalA2averagingA2andA2correctA2forA2darkA2current
,electronicallyA2excitedA2singletA2statesA2typicallyA2haveA2aA2lifetimeA2ofA2approxiatelyA2-
A2Ans--10^-9A2s
whichA2ofA2theA2followingA2moleculesA2canA2haveA2anA2nA2toA2pi*A2absorption?A2-A2Ans--
CH3-COOH
absorptionsA2inA2theA2UV-
VisA2regionA2ofA2theA2spectrumA2resultA2fromA2theA2excitationA2ofA2___A2energyA2levelsA2-
A2Ans--electronic
forA2theA2absorptionA2ofA2aA2UVA2orA2VisA2photonA2byA2aA2molecule,A2theA2energyA2ofA2theA
2photonA2mustA2beA2___A2theA2energyA2differenceA2betweenA2twoA2levelsA2inA2theA2molec
uleA2-A2Ans--equalA2to
whatA2isA2theA2purposeA2ofA2aA2filterA2wheelA2onA2aA2spectrometerA2withA2aA2gratingA2mon
ochromator?A2-A2Ans--removeA2higherA2orderA2spectraA2comingA2offA2theA2grating
anA2organicA2moleculeA2hasA2aA2lamdamaxA2=A2600A2nmA2andA2aA2molarA2absorptivityA2=A
22000A2M^-1A2cm^-1.A2whatA2typesA2ofA2bondsA2mustA2theA2moleculeA2have?A2-A2Ans--pi
describeA2howA2youA2mightA2performA2aA2photometricA2titrationA2whenA2theA2sample,A2titra
nt,A2andA2productA2allA2absorbA2lightA2-A2Ans--
findA2threeA2wavelengthsA2whereA2theA2sample,A2product,A2andA2titrantA2absorb.A2measur
eA2theA2nineA2molarA2absorptivitiesA2forA2standardsA2ofA2theA2sample,A2product,A2andA2titra
nt.A2measureA2atA2threeA2wavelengthsA2asA2aA2functionA2ofA2titrantA2volumeA2added.A2solv
eA2theA2threeA2simultaneousA2equationsA2forA2theA2concentrationA2ofA2titrant,A2sample,A2a
ndA2product
aA2materialA2containingA2whichA2typeA2ofA2absorptionA2wouldA2makeA2theA2bestA2ink?A2-
A2Ans--chargeA2transfer
aA2materialA2withA2whichA2typeA2ofA2absorptionA2(only)A2wouldA2makeA2aA2goodA2invisibleA
2ink?A2-A2Ans--nA2toA2sigma*
beA2ableA2toA2determineA2eachA2pieceA2ofA2fluorescenceA2diagramA2-A2Ans--
fluorescenceA2(1),A2phosphorescenceA2(9),A2absorptionA2(6),A2predissociationA2(10),A2diss
ociationA2(3),A2intersystemA2crossingA2(7),A2internalA2conversionA2(2),A2externalA2conversi
onA2(5),A2vibrationalA2relaxationA2(4)
youA2areA2measuringA2theA2fluorescenceA2intensityA2fromA2S2A2toA2S0A2forA2aA2moleculeA2
withA2theA2aboveA2diagramA2byA2excitingA2theA2moleculeA2inA2solutionA2fromA2S0A2toA2S3.A
2WhatA2willA2theA2followingA2changesA2doA2toA2theA2fluorescenceA2intensityA2fromA2S2A2toA
2S0?A2HeatingA2theA2solutionA2-A2Ans--decrease
coolingA2theA2solution?A2-A2Ans--increase
, bubbleA2theA2solutionA2withA2O2?A2-A2Ans--remainA2theA2same
bubblingA2theA2solutionA2withA2N2?A2-A2Ans--remainA2theA2same
changeA2theA2excitationA2wavelengthA2toA2correspondA2toA2theA2energyA2ofA2theA2S0A2toA2
S2A2transition?A2-A2Ans--increase
changeA2theA2excitationA2wavelengthA2toA2correspondA2toA2theA2energyA2ofA2theA2S0A2toA2
S1A2transition?A2-A2Ans--decrease
placeA2theA2moleculeA2inA2aA2lessA2viscousA2solventA2-A2Ans--decrease
theA2lifetimeA2ofA2anA2excitedA2tripletA2stateA2canA2beA2asA2longA2as?A2-A2Ans--minutes
theA2purposeA2ofA2theA2referenceA2photomultiplierA2onA2aA2spectrofluorimeterA2isA2toA2-
A2Ans--correctA2forA2variationsA2inA2xenonA2lampA2intensity
givenA2theA2followingA2absorptionA2spectraA2ofA2aA21.5A2xA210^-
4A2MA2organicA2sampleA2inA2aA21A2cmA2pathlengthA2cell,A2theA2absorptionA2isA2mostA2likely
A2fromA2whatA2typeA2ofA2transition?A2-A2Ans--
fluorescenceA2alwaysA2occursA2atA2anA2equalA2orA2smallerA2___A2toA2thatA2ofA2theA2photon
A2absorbed?A2-A2Ans--frequency
withA2anA2emissionA2spectrumA2onA2aA2fluorescenceA2spectrometer,A2theA2excitationA2wav
elengthA2isA2-A2Ans--fixedA2andA2theA2emissionA2wavelengthA2varied
whatA2isA2theA2purposeA2ofA2aA2filterA2wheelA2onA2aA2fluorimeter?A2-A2Ans--
removeA2higherA2orderA2spectraA2fromA2theA2grating
aA2moleculeA2hasA2aA2singletA2groundA2stateA2andA2hasA2theA2followingA2absorption,A2fluor
escence,A2andA2phosphorescenceA2spectra.A2predictA2theA2energyA2levelA2diagramA2ofA2t
heA2moleculeA2-A2Ans--A
inA2aA2fluorescenceA2spectrum,A2theA2fluorescenceA2intensityA2isA2proportionalA2toA2___A2
whereA2C=concentrationA2-A2Ans--C
whichA2ofA2theA2followingA2moleculesA2isA2moreA2likelyA2toA2fluoresce?A2-A2Ans--
naphthaleneA2(notA2sucrose)
atomicA2energyA2levelA2diagramsA2willA2notA2displayA2-A2Ans--vibrationalA2energyA2levels
whatA2isA2theA2approximateA2ionizationA2ofA2NaA2inA2eVA2-A2Ans--
5.2A2(labelledA2asA2suchA2onA2diagram)
