雨课堂学堂在线学堂云《Plant and fertilizer analysis（沈阳农业大学）》单元测试考核答案

Plantandfertilizeranalysis第1题Biuretcanreactwithcoppersaltsinanalkalinesolutiontoformapurple-redbiuretcoppercomplex.Excesscoppersaltsinanalkalinesolutionwillformaprecipitateofcopperhydroxide.Whatiscommonlyusedtoformacomplexwithcopper,actingasacolorreagent?APotassiumsodiumtartrateBTartaricacidCAcetoneDCitricacid第2题Intheformaldehydemethodfordeterminingammoniacalnitrogeninfertilizers,theendpointcolorofthetitrationwithstandardNaOHsolutionisAPhenolphthaleinBMethylredCBromocresolgreenDMethylorange第3题Whendeterminingthebiuretcontentinurea,iftheureacontainsalargeamountofammoniumsalts(morethan2mgper100mLofcolorimetricsolution),itwillformabluecopper-ammoniumcomplex,whichinterfereswiththedeterminationandcausesapositiveerror.第4题Inthecolorimetricmethodfordeterminingthebiuretcontentinurea,thecolorobservedisamixtureofbluecopper-tartrateandpurplebiuret-coppercomplexes.第5题Intheformaldehydemethodfordeterminingthenitrogencontentinammoniumsulfate,25mLofthesamplesolutionisplacedina150mLErlenmeyerflask,and1-2dropsofmethylredindicatorareadded.Ifthesampleturnsred,adjustthepHwith0.1mol/LNaOHtoa____color.第6题Intheformaldehydemethodfordeterminingthenitrogencontentinammoniumsulfate,add5mLof18%neutralformaldehydetothefertilizersolution,followedby20mLofwater.Mixthoroughly,letitstandfor5minutes,add3-4dropsofphenolphthalein,mixwell,andthentitratewith0.2mol/LNaOHstandardsolution.Theendpointiswhenthesolutionchangesfrom____to____to____.第7题Thebiuretcontentinureashouldnotexceed1.0%.Foruseasafoliarfertilizer,itshouldnotexceed____%第8题ntheformaldehydemethodfordeterminingammoniacalnitrogenfertilizercontent,formaldehydereactswithammoniaat____°Cbutabove____°C,hexamethylenetetraminedecomposesandreleasesCO2,affectingthetitration.Chapter2:AssignmentsChapter2:UnitTest第1题Inthedeterminationofphosphorusinsuperphosphateextractusingthephosphomolybdicacidquinolineprecipitationmethod,twocommonlyusedmethodsare()AGravimetric+volumetricBColorimetric+gravimetricCColorimetric+volumetricDAtomicabsorption+colorimetric第2题Thefreeacidinsuperphosphateismainlycomposedof()ASulfuricacid+phosphoricacidBHydrochloricacid+sulfuricacidCHydrochloricacid+phosphoricacidDSulfuricacid+perchloricacid第3题Thefreeacidcontentintop-gradesuperphosphateshouldnotexceed()A5.5%B3.5%C4.0%D4.5%第4题TheneutralizationmethodtodeterminethefreeacidcontentinsuperphosphateinvolvestitratingwithNaOH,andtheendpointismarkedbyacolorchangefromyellowtobrightgreen.第5题Whensuperphosphateissoakedinwater,theextractimmediatelybecomesacidic,dissolvingCaHPO4andCa3(PO4)2,whichincreasesthewater-solublePcontent.Therefore,soakingtimeshouldnotbetoolong.第6题Whendeterminingtheavailablephosphoruscontentinsuperphosphate,ifthesolution'sacidityistoolow,theprecipitatewillage,andheatingmaycausesplashinglosses.Additionally,theprecipitate'sphysicalpropertiesarepoorundertheseconditions.第7题PhosphomolybdicacidquinolineprecipitationcanbecarriedoutinHClorHNO3solutions.ItisgenerallynotadvisabletouseH2SO4aloneasanacidicmedium,as____willformawhiteprecipitateinH2SO4,leadingtoahighresult.第8题Intheprocessofgeneratingphosphomolybdicacidquinolineprecipitateswhendeterminingavailablephosphorusinsuperphosphate,thesolutionacidityisgenerallyrequiredtobe____mol/L.第9题Using____asanindicatorgivesthetotalaciditybutcannotseparatelymeasureH2SO4andH3PO4.Tomeasurethemseparately,adoubleindicatormethodmustbeused.第10题Availablephosphorusinsuperphosphateexistsinbothwater-solubleand____formsChapter3:AssignmentsChapter3:UnitTest第1题Whendeterminingpotassiumcontentinasolutionusingthesodiumtetraphenylborategravimetricmethod,theconcentrationofNaTPBusedfortheprecipitationreactionis()A1.5%B0.1%C0.5%D1.0%第2题Inthesodiumtetraphenylborategravimetricmethodfordeterminingpotassiumcontent,theprecipitateresidueshouldbewashedwith()ADistilledwaterB0.1%sodiumtetraphenylborateC0.5%sodiumtetraphenylborateD1.5%sodiumtetraphenylborate第3题Themethodsfordeterminingpotassiumcontentinasolutioninclude()ASodiumtetraphenylboratemethodBSodiumtetraphenylboratevolumetricmethodCFlamephotometryDAtomicabsorption第4题Inthisexperiment,thewashingmethodfortheprecipitateis____.第5题Thedryingtemperaturefortheprecipitateinthisexperimentshouldnotexceed____°C.第6题Theconcentrationofsodiumtetraphenylborateusedforwashingtheprecipitateis____.第7题Duringtheexperiment,thesodiumtetraphenylboratesolutionmustbeaddedquicklytoavoidforminglargeparticlesofprecipitate.第8题Afteruse,thesurfaceprecipitateinthecrucible-typefunnelcanbescrapedcleanwithablade.Chapter4:AssignmentsChapter4:UnitTest第1题Whendeterminingnitrogencontentinmixedfertilizers,beforestartingthedistillation,itisnecessarytoadd()andanindicatortothereceivingflask.ASulfuricacidsolutionBBoricacidCStandardsulfuricacidDSodiumhydroxide第2题Whendistillingnitrogen,ifthedistillationapparatusisnotairtight,theresultwillbe().AToolowBToohigh第3题Whendeterminingnitrogencontentinmixedfertilizers,ifthesamplecontainsnitratenitrogen,itshouldfirstbe____.第4题Afterfiltration,theyellowphosphomolybdicacidquinolineprecipitateintheglasscrucible-typefunnelcanfirstbewashedwithtapwater.Theremainingprecipitatecanthenbedissolvedwithasmallamountof1:1____solutionforcleaning.第5题Whendeterminingtheavailablephosphoruscontentinsuperphosphate,theamountofcitricacidmustbeappropriate.Toolittlewillresultinpoorphysicalpropertiesoftheprecipitate.第6题Inthetotalnitrogendeterminationformixedfertilizers,allformsofnitrogen,exceptammoniumnitrogen,mustbeconvertedtoammoniumnitrogenbeforedistillationandtitration.第7题Inthedistillationtitrationmethodfordeterminingnitrogencontentinmixedfertilizers,thereactioninthedistillationflaskconvertsammoniumnitrogenintoammoniagasunderalkalineconditions.第8题Inthedistillationtitrationmethodfordeterminingnitrogencontentinmixedfertilizers,thereactioninthereceivingflaskinvolvesammoniagasreactingwithsulfuricacidtoformammoniumsulfate.第9题Whendeterminingtheavailablephosphoruscontentinamixedfertilizercontainingsuperphosphateandammonia-treatedsuperphosphate,waterandalkalineammoniumcitrateareusedforextraction.第10题Whendeterminingnitrogencontentinmixedfertilizers,afterdistillation,thesolutioninthereceivingflaskistitratedwithsodiumhydroxide,andtheendpointcolorisgray-greenwhenmethylred-methyleneblueisusedastheindicator.Ifmethylredisused,theendpointcolorisorange-yellow.Chapter5:AssignmentsChapter5:UnitTest第1题Whendeterminingtheorganicmattercontentinorganicfertilizers,thesamplemustfirstbe____beforecarbonization.第2题Whenusingthedryashingmethodtodeterminethetotalorganicmatterinorganicfertilizers,thesampleisfirst____atlowtemperaturesandthenburned____athightemperaturesto525°C.Theorganicmatterdisappearsintheformof____andwater,andthelossinweightisthetotalorganicmattercontent.第3题Whenaddingorganicfertilizersamplestothedigestiontube,thesampleshouldbeplacedatthebottomofthetubeandshouldnottouchthetubewalls.第4题ThepurposeofaddingchromiumgranuleswhendeterminingthetotalnitrogencontentinorganicfertilizersistoreduceNO3–NtoNH4+–N.第5题Ifthereisasignificantamountofblackresidueafterdigestionoforganicfertilizersamples,itindicatesincompletedigestion.第6题Whendeterminingthetotalnitrogencontentinorganicfertilizers,thesampleshouldbeheatedfor5minutesatlowtemperatureinthedigestionfurnacetoensureallchromiumgranulesdissolve.Otherwise,thereactionbetweenthechromiumgranulesandhydrochloricacidmaygeneratelargeamountsofhydrogengasandfoam,leadingtolosses.第7题Thepreparationofthetestsolutionfromorganicfertilizersamplesusingperchloricacidandsulfuricaciddigestioncanbeusedforthedeterminationoftotalphosphorusandtotalpotassium.第8题Whenusingthedryashingmethodtodeterminetheorganicmattercontentinorganicfertilizers,thetemperatureforcarbonizationshouldnotbetoohigh;onlyafterthesamplestopsemittingblacksmokeshouldthetemperaturebeincreased.Chapter6:AssignmentsChapter6:UnitTest第1题Thewatercontentinplantscanbeclassifiedas()andboundwater.AFreewaterBBoundwater第2题Whenusingatoluene-waterazeotropicmixturefordistillation,theboilingpointgradually().ADecreasesBIncreases第3题Thefollowingmethodscanbeusedtodetermineplantmoisturecontent().AHeatinganddryingmethodBDistillationmethodCChemicalreactionmethodDPhysicalmethod第4题Whenusingtheheatinganddryingmethodtodeterminesamplemoisturecontent,itisnecessarytoensureallwateriscompletelyremovedfromthesample,andthethermalreactionsofothercomponentsduringheatingcanbeignored.第5题Theheatinganddryingmethodiswidelyusedandiscommonlyemployedformoisturedeterminationinplants,soil,andorganicfertilizers.第6题Theheatinganddryingmethodissuitablefordeterminingmoisturecontentinfreshsugarcane.第7题Thedistillationmethodissuitablefordeterminingmoisturecontentinfreshplantsampleswithahigherwatercontent.第8题Whenusingtheheatinganddryingmethodtodetermineplantmoisture,theovenshouldbemaintainedatabout105°Ctoensurerapidmoistureremovalwithoutlosingothercomponentsduetoprolongeddrying.第9题Intheazeotropicdistillationmethodfordeterminingplantmoisturecontent,ahighheatsourcemustalwaysbemaintainedtoensurecompletemoistureevaporation.第10题Theazeotropicmixtureoftolueneandwaterlowerstheboilingpointofwater.第11题Intheazeotropicdistillationmethod,allcomponentsmustbesealedtightlytoavoidgasleakage.第12题Intheazeotropicdistillationmethod,allcomponentsmustbedry.第13题Intheazeotropicdistillationmethod,startwithlowheat,andincreasetheheatasthedistillationnearscompletion.Thevolumeofmoisturecanbereadoncethereceivernolongerincreasesinwatercontent.第14题Intheazeotropicdistillationmethod,openflameheatingshouldbeavoided.Chapter7:AssignmentsChapter7:UnitTest第1题Whendeterminingnitrogencontentinplants,beforestartingthedistillation,itisnecessarytoadd()andanindicatortothereceivingflask.ASulfuricacidBBoricacidCHydrochloricacidDSulfuricacid第2题Whendeterminingnitrogencontentinplants,beforestartingthedistillation,itisnecessarytoaddthereceivingsolutionandindicatortothereceivingflask,andadjustitto().ABlue-greenBWineredCGreenDBlue第3题Inthesemi-microdistillationmethodfordeterminingnitrogencontentinplants,ifinsufficientNaOHisaddedtothedistillationchamber,theresultwillbe____.第4题Whendeterminingphosphoruscontentinplants,afteraddingtheindicator,thesolutionshouldbeadjustedtoa____color.第5题Whendeterminingnitrogencontentinplants,theendpointcolorwhentitratingthedistillateinthereceivingflaskwithstandardacidis____.第6题Whendeterminingphosphoruscontentinplants,____isusedasanindicator.第7题Whendeterminingpotassiumcontentinplants,thereisnoneedtoaddblankdigestionsolutionwhenpreparingthestandardseries.第8题IfexcesshydrogenperoxideisaddedduringthedigestionofplantsampleswithH2SO4-H2O2,itshouldbeheatedtoexpelit,asitmayaffectphosphorusdetermination.第9题Inthesemi-microdistillationmethodfornitrogendeterminationinplants,theheatshouldbeincreasedatthestarttoquicklyreleaseammoniagasandacceleratetheexperiment,ensuringproperdistillationquality.第10题Tosavetimeduringthedigestionprocessforplantsamples,concentratedH2SO4andH2O2canbeaddedtothedigestiontubecontainingthesample12hoursbeforedigestion.Chapter8:AssignmentsChapter8:UnitTest第1题Toreducephosphorusloss,planttissueswithhighphosphoruscontentaregenerallytreatedwith()duringdryashing.APotassiumsulfateBHydrochloricacidCCalciumchlorideDMagnesiumacetate第2题Theashcontentdeterminedbythedryashingmethodis().ACoarseashBWater-insolubleashCWater-solubleashDAcid-solubleash第3题Thedirectashingmethodisnotsuitablefor().AVegetablesBFruitsCWhitesugarDPlantstemsandleaves第4题Pre-ashinginthedirectashingmethodisdonetoreducelossesduringtheashingprocess.第5题Afteraddingashingauxiliaries,higherashingtemperaturesarebetter.第6题Theformationofinsolublecomplexsilicatesduringtheashingprocessaffectsthedeterminationofcoarseash.第7题Indryashing,thetemperatureshouldbecontrolledat____°C.第8题Toreducephosphoruslossduringtheashingprocess,____shouldbeadded.第9题Iftheweightdifferencebeforeandafterburningthesampledoesnotexceed____mg,thesampleisconsideredtohavereachedaconstantweight.第10题Tospeeduptheashingprocess,asmallamountofdistilledwateror____canbeaddedduringtheburningprocess.Chapter9:AssignmentsChapter9:UnitTest第1题Plantstypicallycontainhigherlevelsof()elements,particularlyinseeds,whilecalciumandmagnesiumlevelsarerelativelylow.Thiselementtendstoformcompoundswithcalcium,soitmustbeconsideredwhendeterminingcalciumandmagnesiumcontent.ANitrogenBPhosphorusCPotassiumDSulfur第2题Whendeterminingcalciumandmagnesiuminplantsamplesusingthewetashingmethod,whichacidisusedtopreventtheformationofprecipitateswithcalcium?ANitricacidBHydrochloricacidCPerchloricacidDSulfuri