物质的分离与提纯Separation and purification of substances.docx
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物质的分离与提纯Separation and purification of substances.docx
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物质的分离与提纯Separationandpurificationofsubstances
物质的分离与提纯(Separationandpurificationofsubstances)
ThebasicoperationsintheseparationandpurificationofmaterialsarecollectedintoQQbookmarks.Author:
adminClick:
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Theresultisnotideal[nationaltopteachervideotutoringhighschoolcurriculum]fartitlesea,nearapproach!
Highentrance,hightwoentrance,highthreeentrance
I.teachingcontent:
basicoperationsintheseparationandpurificationofsubstances,neutralizationtitration
Two.Keyanddifficultpoints:
Three.Knowledgeanalysis:
1.thebasicoperationofseparationandpurificationofsubstances
Operationname
Scopeofapplicationandexamples
device
Operationpoints
Filtration(precipitation,washing)
Solid(insoluble)liquidseparation
Cases:
theremovalofsaltinsediment
(1)foldthefoldedfilterpaper,closetothefunnelwall,andthewatercannotbewetuntilthebubble,theedgeofthefilterpaperislowerthanthefunnel.Whenthefilterisadded,thesolutionsurfaceofthefunnelislowerthantheedgeofthefilterpaper,thatis,apastetwolowandthreelean".
(2)whenfiltering:
thebeakermouthisincontactwiththeglassbar;theglassrodcontactswiththethreefilterpaper;thefunnelmouthisclosetotheglassbeakerwall.
(3)water,threetimeshigherthanthesurfaceprecipitation,immersion,purifytheprecipitation.
Evaporationcrystallization(recrystallization)
Solidliquidseparation:
evaporationcrystallizationofsaltsolution.
Theuseofsubstancesinthesamesolventindifferentsolvents,thesolid,asolid(homogeneous)separation.Example:
crystallizationseparationofKNO3andNaCl.
(1)theevaporatingdishcanbeheateddirectly.Fixedtheironhoop.
(2)theglassrodconstantlyagitatedbyheatingtopreventhotliquidspills,findmoresolidsolutionwhendryingthefireevacuation.Steamthesolutionwithwasteheat.
Distillationfractionation
Aliquidmixturethatseparateboilingpoints
Example:
thefractionsarefractionatedfrompetroleum.Ethylacetatewasdistilledfromethanol,aceticacidandconcentratedH2SO4mixture.
(1)thedistillationflaskisheatedwithasbestosnet,andthethermometerandmercurybulbareplacedintheslightlydownwardpositionofthebranchpipe.
(2)whenthetotalhorizontalcondensationtubetoensurelowcondensatenaturalcoolingwaterisdirty,andcondensedvaporflowsintheopposite.
(3)theflaskintoporousceramicwithantibumping.
Extractionseparation
Separatethetwomiscibleliquids.Separatetwomutuallyinsolubleliquids.
Example:
useCCl4toextractiodinefromiodinewater,thenseparateit
(1)thesolutionisinjectedintoaliquidseparatingfunnel,andthetotalamountofthesolutiondoesnotexceed3/4ofthevolume;asshown,thetwohandsholdtheliquidseparatingfunnelandtheinvertedliquidfunnelandoscillaterepeatedlyandvigorously.
(2)theseparatoryfunnelontheironhoops,staticlayered.
(3)openthecocktomakethelowerliquidrunout.
Gaswashing
Airseparation(impuritygasreactswithreagent):
removeHClimpuritiesinCl2gaswithsaturatedsaltwaterandremoveC2H2inCH4withBr2water.
Mixinggasintoawashingbottle
Payattentiontotheflowofgasandmakeprogressshort.
Dialysis
Separationofcolloidalparticlesfromsolutesinsolution.Example:
theremovalofNaClfromstarchcolloidsbydialysis.
Willbepurifiedintothecolloidmembrane,themembranebag,immersedindistilledwater,dialysistimetofully.
heating
Impurityreaction.Example:
Na2CO3containsNaHCO3impurities.MnO2mixedwithcarbonpowder,impuritiescanberemovedbyheating.
Stirwithglassrodstokeeptheheatevenly
sublimation
Separatesubstancesthatsublimateeasily.Example:
purificationofiodineandnaphthalene
Saltingout
Thecolloidisseparatedfromthemixture.Example:
sodiumsaltisaddedtothesodiumstearatesolution,andsaturatedsolutionisaddedtotheeggwhitesolution
Ionexchange
Separatetheionsfromtheliquid.Example:
softeningandhardening
2.neutralizationtitration
Titrationprocess:
Stance:
thelefthandcontrolsthepistonorsmallball,therighthandshakestheconicalflask,andtheeyelooksatthechangeinthecolorofthesolutionintheconicalflask.
Driprate:
dropbybit,andwhenapproachingtheend,rollonebyone.
Finish:
thelastdropisjusttheendofthetitrationwhentheindicatorcolorchangesmarkedly.Recordreading(halfaminutewithoutfading)
Dataprocessinganderroranalysis
3.gasgeneratortightnesscheck(seeFigure1andFigure2)
Figure1,figure2
Suchasgasexperimentdevicemore,alsocanconsiderthemethodofsubsectioninspection,theprincipleisthesameasabove.
Thepurificationofsubstancesistheremovalofimpurities.Itreferstotheexperimentaloperationofremovingimpuritiesfromasubstancetoincreasepurity.Theseparationofsubstancesistheexperimentalprocessofseparatingtheconstituentsinthemixture.Therefore,separationcanbeseenasanextensionofpurificationmethods.
1.questions:
Istheuseofchemicalreactiontoimpuritiesintogasorinsoluble(orviceversa)andremoved(removalmethod),ortheimpuritiesintotherequiredmaterial(conversion),butshouldpayattentiontonotbecauseofaddingreagentandintroducingnewimpurities.Thatis:
Canbesummedupas"noincrease,nodecrease","easyseparation"and"recovery"".
3.purificationofsolidsorsolutions:
(2)conversionmethod.Suchas:
NaHCO3(Na2CO3),Na2CO3(NaHCO3),FeCl2(FeCl3),andFeCl3(FeCl2)
(1)commonreagentsfortheremovalofimpuritiesingases:
RemovalofHClinCl2gas:
adsorptionwithactivatedcarbon(Cl2easyliquefaction)
Removeacidgasorhalogen:
usealkalisolution.
(2)dryingofgasadoptsdesiccant
Concentratedsulfuricacid:
inadditiontonondryingH2S(becauseofsulfuricacidoxidation,H2Sreduction),NH3,almostallcanbeused.
Basicdesiccant
Solidcausticsoda:
cannotdrysourgas.
Alkalilime:
notdryacidgas.
Neutralornearneutraldesiccant
Silicagel:
almostallavailable.
Anhydrouscalciumchloride:
almostallexceptNH3andethanol.
5.removalofimpuritiesinthematerial:
Ifthesodiumsulfatesolutioncontainsasmallamountofsodiumcarbonateorothervolatileweakacidsodiumsaltimpurities,addaproperamountofsulfuricacidcanbe.Na2CO3H2SO4=Na2SO4H2OCO2-
SuchasZnCl2(ZnSO4):
addaproperamountofBaCl2solution.ZnSO4BaCl2=BaSO4-ZnCl2
Na2CO3(NaHCO3):
heatingoraddingalkali.
(4)removalofimpuritiesbyoxidation-reductionreactions
Replacementreactionscanbeusedifrelativelyactivemetalsaltsolutionscontainimpuritiesinthesaltsofinactivemetals.Forexample,FeSO4(CuSO4):
addingironpowdertofiltratethefiltrate.FeCuSO4=FeSO4Cu
FeCl3(AlCl3):
addedexcesscausticsolution,filteredandprecipitatedwithhydrochloricacid.
(6)removalofimpuritiesinorganicmatter
Suchasbenzenemixedwithphenol:
addNaOHsolution,delaminationremoved.
Ethylacetatemixedwithaceticacid:
saturatedwithsodiumcarbonatesolution,delaminationremoved.
6.note:
)(theremovalofimpuritiesinthesaltwaterforelectrolysisofalkali)shouldbe:
Ba2
(2),inthespecificexperimentprocess,itisalsonecessarytoselecttheappropriateinstrumentandcorrectoperation.Forexample,whentheimpuritiesareremovedinthesolution,theprecipitateproducedmustberemovedbyfiltration.Ifproducegas,shouldusetheheatingmethod,makeitmorethoroughlyandreducethesolubility,theremovaloftheimpurities;ifagaspurificationabsorptionmaterial,theabsorbentisaliquid,withgaswashingmethod;absorbentissolid,withadryingtube.Iftheimpuritiesareseparatedbyliquid-liquidextraction,aseparateliquidfunnelisused.
Feasibility:
ifH2S(HCl),donotuseFeS,becauseFeSisdifficulttoreactwithHClgas;
Purity:
ifCO2(H2S),cannotuseconcentratedsulfuricacid,becauseproduceSO2;
Ordering:
Cl2(HCl,H2O),firstthroughsaturatedsaltwater,andthenthroughconcentratedsulfuricacid.
Impurityremovaltechnique:
(1)inanexperimentaldeviceforproducinggasandremovingimpurities,ifthereisacoppersulfatesolutioninthegaswashingtank,itmustbeusedtoremovehydrogensulfidegas.
(2)toremoveasetofimpurityionsseparately,andonlyoneionatonetime,andthereagentmustbeexcessive,thefinalimpurityremovalreagentmustbeacid,andthelastsecondaresolublecarbonates.Theadvantageofusingcarbonateisthatitdepositsmorecationsandiseasytoremove(plusthecorrespondingacid).
(3)CO2gasmixedwithSO2orHClgas,canpassintotheNaHCO3solution,SO2solutionbecauseofsulfurousacidinwater,sulfuricacidandhydrochloricacidcanreactwithNaHCO3toformCO2,whichremovedtheimpuritygas,andincreasetheamountofmaincomponent;similarly,SO2gasmixedwithHClgascanpassintotheNaHSO3solution,hydrochloricacidandNaHSO3reactionofSO2gas.
[typicalexample]
[example1]howtoremoveasmallamountofCO2inCO?
Analysis:
becauseCOreactswithO2toproduceCO2,somestudentsthinkthatO2canbepassedintothemixtureandignitedtoremovetheCO.Themistakewiththisideaisthatwhenaflameisusedtoigniteamixtureofgases,theflameisextinguishedbythepresenceoflargeamountsofCO2;COcannotburn;andO2impuritiesareintroduced.Therefore,wemustnotconsiderthespecificcircumstancesandconditions,andconsidertheimpurityremovalmethodsinisolation.Thecorrectsolutionis:
themixedgasbyhotCuO,thereactionis:
CuOCOexercises:
CaCl2(NaCl)
Ethaneismixedwithethylene.Withtheconversionmethod,H2,yield,butharshconditions,cannot
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