光盘分光光度 spectrophotometer of optical disk.docx

光盘分光光度 spectrophotometer of optical disk.docx

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光盘分光光度spectrophotometerofopticaldisk

光盘13-3分光光度（13-3spectrophotometerofopticaldisk）

ThethirteenthchapterSpectrophotometry

1.writetheformulaofLambertBill'slawandexplainwhatthesymbolsrepresent

[answer]LambertBeer'slawformula:

A=kappaBC

Aistheabsorbance;Bisthethicknessoftheabsorptioncell（liquidlayerthickness）,theunitiscm;theCistheconcentrationofthesubstancemeasured（mol;L-1）;thekappaisthemolarabsorptioncoefficient,theunitisL.Mol-1.Cm-1.

LambertBeerlawcanalsobeexpressedas:

A=AB?

Massconcentration（G?

L-1）;aisthemassabsorptioncoefficient,andtheunitisL.G–1.Cm-1.

Aandkappacanbeconvertedbythefollowing:

kappa=aM

Mintheformularepresentsthemolarmassofthesubstancetobemeasured.

2.,inordertoimprovethesensitivityandaccuracyofspectrophotometry,whatmustbeconsideredwhendesigningexperiments?

[answer]inordertoimprovethesensitivityandaccuracyofmeasurement,wemustconsiderthefollowingaspects:

（1）themaximumabsorptionwavelengthischosenastheincidentwavelength;

（2）theordinaryspectrophotometershouldmeasuretherangeofA=0.2~0.7byadjustingtheconcentrationofthesampleandthethicknessoftheliquidlayer.

3.whatisabsorptionspectrum?

Whatisastandardcurve?

Whatarethepracticalapplicationsofeachmethodinspectrophotometry?

[a]

（1）thedifferentwavelengthsofmonochromaticlightisfollowedbytheanalysisofthematerial,themeasuredabsorbanceAunderdifferentwavelengthtowavelength?

AstheabscissaandtheAabsorbanceasordinate,theavailabilityofacurveistheabsorptionspectrum（absorptionspectrum）（absorptioncurve）orabsorptioncurve.Absorptionspectrumreflectsthecharacteristicsofmatter,anditisthebasisofqualitativeandquantitativeanalysis.Themaximumabsorptionwavelength（max）canbedeterminedintheabsorptionspectrum.Inordertoimprovethedetectionsensitivity,Maxwavelengthischosenastheincidentwavelengthingeneraldetermination.

（2）thestandardcurvemethodisstandardwithaseriesofstandardsolutionofknownconcentrationatselectedwavelengths（usually?

Max）,weremeasuredbyabsorbanceabsorptioncellwiththesamethickness,theabsorbanceasordinate,theconcentrationofstandardsolutionasabscissamapping,astraightlinethroughtheoriginofcoordinatesstandardcurve?

?

.Thenthemeasuredsolutionisplacedintheabsorptioncell,andtheabsorbanceismeasuredunderthesameconditions.Thecorrespondingcontentcanbefoundonthestandardcurveaccordingtotheabsorbance.

4.visibleandultravioletspectrophotometerusuallyconsistsofseveralpartsWhatisthefunction?

[a]visibleandultravioletspectrophotometerisusuallycomposedoffiveparts,

（1）radiationsource;

（2）monochromator;（3）absorptioncell;（4）photodetector;（5）readingindicator.

Theradiationsource:

radiationsourceemitscontinuousradiationlightwithsufficientstrengthandstability.

Themonochromator:

monochromatorisopticaldeviceintomonochromaticlightcompositelightradiatedfromalightsourceinthe.

Theabsorptioncell:

ultravioletandvisiblespectrophotometry,themeasuredliquidonthespectrophotometerpassingthroughaliquidpool,containerforholdingsolutioniscalledtheabsorptionpool.Theabsorptioncellinthevisibleregioncanbedirectlymadeofopticalglass.Whiletheultravioletregionisquartzabsorptioncell.

Thephotosensitivedetector:

thesignallightsignaltoelectricaltransformation.

Thereadingindicator:

displaytheresults.

5.inspectrophotometry,howtochooseblanksolution?

[a]inthedeterminationofabsorbance,solventorothersubstancesinordertoeliminatetheabsorptionofincidentlight,andthelightscatteringinsolutionandabsorptioncellboundariestotheeffectoflightreflectionandabsorptionwereindependentfactors,mustusetheblanksolution（blanksolution）ascontrol.Therearethreekindsofblanksolutionscommonlyusedinthevisibleregion.

（1）whenthesolventblankreagentandpreparationofsamplesolution,allotherreagentsavailableforcolorless,solventblanksolution.

（2）ifthereagentblankiscolored,andthesamplesolutionisnotabsorbedorabsorbedundertheconditionofdetermination,thereagentblankcanbeusedforcorrection,

Thatis,accordingtothesameconditionsofcolorreaction,addingvariousreagentsandsolvents（withouttestingsamplesolution）,thesolutionisequivalenttothestandardcurvemethodofconcentrationof"0"standardsolution.

（3）blanksample,whenthesamplematrixiscolored（suchasmixedwithothercoloredionsinthesamplesolution）,butthechromogenicagentiscolorless,anddoesnotshowthecolorofothercomponentsotherthanthecomponentinthesample,theblankcanbecorrectedbysampleblank.Thatis,asamplesolutionwithouttheadditionofadeveloperbutunderthesameconditionsasthecolorreaction.

6.ordinaryspectrophotometergenerallycontrolabsorbanceintherangeof0.2~0.7,andtheuseofhighqualityinstrumentabsorbancecanbe2orgreater,trytoexplainthereasons.

[answer]theconcentrationmeasurementerrorofspectrophotometerdependsonthereadingresolutionoflighttransmittanceTanddependsonothermeasurementenvironments.Forordinaryspectrophotometerreadingerrorcausedbythelimitedresolution?

T,thegeneralcontrolofabsorbanceintherangeof0.2~0.7,butifthespectrometerwithhighaccuracy,themainerrorsourcesbutnotreadingresolution,duetorandomfluctuationofphotomultipliertubeandaphotoelectrictubeoutput,thentheabsorbanceofthiskindofinstrumentcanbeusedin2ormore.Theexperimentalreportsusuallyindicatethetypeandmanufactureroftheinstrumentsused.

7.convertthefollowingtransmittancetoabsorbance

（1）99%

（2）75%（3）50%（4）10%（5）1%

[answer]

（1）0.0044

（2）0.125（3）0.301（4）1（5）2

8.convertthefollowingabsorbancetolighttransmittance

（1）0.01

（2）0.10（3）0.50（4）0.70（5）1

[answer]

（1）97.7%

（2）79.4%（3）31.6%（4）20%（5）10%

9.theconcentrationofacoloredsolutioninaccordancewithLambertBilllawisCmol?

L-1,andthetransmittanceisT,

Thesolutiontotheoriginal1/2,thetransmittanceishowmuch?

Thethicknessofliquidlayerofcoloredsolutionafterdoublingthenumberforthetransmittanceandtheabsorbancechange?

[solution]accordingtoLambertBilllawformula:

A=kappaBC

A=-lgT

Thesolutiontotheoriginal1/2,Ato1/2,thenthetransmittanceisT1/2

Theliquidlayerthicknessdoubledwaschangedto2A,thenthetransmittanceisT2.

10.thefollowingistrue

ThemaximumabsorptionwavelengthofA.becomeslongerwhentheconcentrationofsolutionincreases;

B.whenthewavelengthisfixed,theconcentrationofthesolutionbecomessmaller,andtheabsorbancedecreases;

ThethicknessofC.absorptioncellisdoubled,anditsmolarabsorptioncoefficientisdoubled;

ThesmallertheslopeofD.standardcurve,thehigherthesensitivityofdetection.

[answer]chooseB.

11.forthelightabsorbingsubstance,thefollowingfactorsaffectthemolarabsorptioncoefficient

A.absorptioncellthicknessB.theconcentrationofC.absorptionmaterialD.incidentlightwavelength

[answer]D

12.whatiswronginthefollowingstatementsisthat:

A.LambertBilllawisonlysuitableformonochromaticlight;

B.lightsourceshouldbeselectedinthevisiblelightrangeishydrogenlamp;

C.blanksolutionisusedtoadjustthezeropointoftheinstrument;

IfD.changestheincidentwavelength,theabsorbancechanges.

[answer]chooseB.

13.,themolarabsorptivityofasubstanceisverylarge

A.thematerialhasastrongabsorptioncapacityforacertainwavelength.B.hasalargeconcentrationofthissubstance

TheC.lightismeasuredbyD.ofthelengthofthesolution,andtheprecisionofthesubstanceisveryhigh

[answer]chooseA.

14.AandBwiththesamemass,themolarmassofwhichistwo.Whenthesolutionofthesamevolumeisprepared,theabsorbanceofthesolutionisequal,andthefollowingistrueabouttherelationshipbetweentheirmolarabsorptivity

A.B.C.D.

[answer]chooseD.

15.whenthecontentofironwasmeasuredbyspectrophotometry,theexcessNH4SCNwasaddedintheacidicsolutionofthesample,whentheabsorptioncellwasusedastheabsorptioncell

Whenthethicknessis1cm,

Bymeasuringthedatalistedinthetable,itispossibletodeterminewhetherthesolutionfitsLambertBilllaw

W（Fe）/%

Zeropointzeroone

Zeropointzerotwo

Zeropointzerofour

Zeropointzeroeight

T/%

Eighty

Sixty-fourpointeight

Forty-four

Twenty-two

?

[solution]thelighttransmittanceisconvertedtoabsorbancevalueasfollows:

W（Fe）/%

Zeropointzeroone

Zeropointzerotwo

Zeropointzerofour

Zeropointzeroeight

T/%

Eighty

Sixty-fourpointeight

Forty-four

Twenty-two

A

Zeropointzeroninesixnine

Zeropointoneeighteightfour

Zeropointthreefivesixfour

Zeropointsixfivesevensix

Becausetheratioofabsorbanceisnotequaltotheratiooftheconcentration,thesolutiondoesnotconformtoLambertBilllaw.

16.vitaminD2（thatis,calciumalcoholC28H43OH）dissolvedinethanol,molarabsorptivityat265nm?

=18250L?

Mol-1?

Cm-1.Themassabsorptioncoefficientofa=?

Iftherequirementsofmeasuringtheabsorbancelimitintherangeof0.2~0.7,analyzewhatistheconcentrationrange?

Thethicknessoftheabsorptioncellisassumedtobe1cm.

[1]solutionaandkappaandthemolemassMfor:

therelationshipbetweenkappa=a?

M

M（C28H43OH）=396.3G?

Mol-1

A=kappa/M=18250L?

Mol-1?

Cm-1/396.3g=mol-1=46.05L?

G?

Cm-1

TheLambertBill'slawformula:

A=kappaBC

Theabsorbancelimitwasmeasuredinthe