2023年全國碩士研究生考試考研英語一試題真題（含答案詳解+作文范文）_第1頁
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1、34.1.14AOACOfficialMethod948.13GlycerolinEggsQuantitativeMethodFirstAction1948FinalActionA.Reagents(a)Sodiumtungstatesolution.—Dissolve10gNa2WO4?2H2Odiluteto100mL.(b)Potassiumperiodatesolution.—0.02M.Dissolve4.6gKIO4inca

2、500mLhotH2Odilutetoca900mLwithH2Ocooltoroomtemperaturediluteto1L.Testfalkalinitybyadding0.01MH2SO4to25mLofthesolutioncontainingbromocresolpurple(c).Donotuseif1acidisrequiredtogiveyellowacidcol.(c)Bromocresolpurpleindicat

3、.—Dissolve0.1gbromocresolpurplein100mLalcoholfilterifnecessary.(d)Calciumoxidepowdered.—ACSReagentgrade.B.Determination(a)Eggswithnoaddedsugars.—Weighbydifferenceca2gwellmixedtestption925.29(a)(b)(see34.1.01)into100mLvol

4、umetricflaskcontaining50–75mLH2O.Recdsampleweighttonearest0.0001g.Mixadd2.0mLNa2WO4solution.Slowlyadd2.0mL0.5MH2SO4withcontinuousmixing.DilutetovolumewithH2Omixwellfilter(18.5cmfoldedpaper).Transferaliquotoffiltrateconta

5、ining≤40mgglycerolto300mLErlenmeyerflaskdilutewithH2Oto20mLifnecessary.Add2mL10%NaOHsolutionheattobpboil30s.Coolslightlyadd3sbromocresolpurple.Usingaburetneutralizewith0.5MH2SO4add1–2sexcess.Boil1mincooltoroomtemperature

6、neutralizecarefullywith0.02MNaOHtitratingtolightpurple.Quantitativelytransferneutralsolutionto100mLvolumetricflaskrestrictingtotalvolumeto1acidisrequiredtogiveyellowacidcol.(c)Bromocresolpurpleindicat.—Dissolve0.1gbromoc

7、resolpurplein100mLalcoholfilterifnecessary.(d)Calciumoxidepowdered.—ACSReagentgrade.B.Determination(a)Eggswithnoaddedsugars.—Weighbydifferenceca2gwellmixedtestption925.29(a)(b)(see34.1.01)into100mLvolumetricflaskcontaini

8、ng50–75mLH2O.Recdsampleweighttonearest0.0001g.Mixadd2.0mLNa2WO4solution.Slowlyadd2.0mL0.5MH2SO4withcontinuousmixing.DilutetovolumewithH2Omixwellfilter(18.5cmfoldedpaper).Transferaliquotoffiltratecontaining≤40mgglycerolto

9、300mLErlenmeyerflaskdilutewithH2Oto20mLifnecessary.Add2mL10%NaOHsolutionheattobpboil30s.Coolslightlyadd3sbromocresolpurple.Usingaburetneutralizewith0.5MH2SO4add1–2sexcess.Boil1mincooltoroomtemperatureneutralizecarefullyw

10、ith0.02MNaOHtitratingtolightpurple.Quantitativelytransferneutralsolutionto100mLvolumetricflaskrestrictingtotalvolumeto50mL.Asaidmarksideofflasktoindicatevolumeofca45mL.Ifnecessaryaddme0.02MNaOHtomaintainlightbutdefinitep

11、urple.Continueasin942.22F(b)(see15.6.02)beginning“...add50mLKIO4solution.”using942.22G(a)(see15.6.02)fdetermination.Excessperiodatemustbepresentafteroxidation.Ifperiodatetestisnegativerepeatdeterminationusingsmalleraliqu

12、ots.(b)Eggscontainingaddedsugars.—Weighbydifferenceca2gwellmixedtestption925.29(a)(b)(see34.1.01)into100mLvolumetricflaskcontaining50–75mLH2O.Recdtestptionweighttonearest0.0001g.Mixadd2.0mLsodiumtungstatesolution.Slowlya

13、dd2.0mL0.5MH2SO4withcontinuousmixing.Dilutetovolumewithwatermixwellfilter(18.5cmfoldedpaper).Transferaliquotoffiltratecontaining≤40mgglycerolto400mLbeaker.Adjustvolumeto20mLbyevapationonsteambathbyadditionofH2O.Add0.5gpo

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