高中化学计算题High school chemistry problem.docx

高中化学计算题High school chemistry problem.docx

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高中化学计算题Highschoolchemistryproblem

高中化学计算题

（一）（Highschoolchemistryproblem

（1））

ThesecondmethodUSESthelawoftheconservation,sothecomputationalcomplexityismuchless,alsodonotneedchemicalequationislistedfirst,balancing,therebysignificantlyshortenaboutthetime,notIdon'tknowaccordingtowhichoneismoreequationstopanic,asaresultofnitricacid.Thenlookatthetopic:

[example2]ina6litresofairtightcontainer,add3X（gas）and2litresY（gas）,undercertainconditionsthefollowingreaction:

4X（gas）+3（gas）Y（gas）2q+nR（gas）afterreachingbalance,container,constanttemperatureofmixedgaspressureincrease5%thantheoriginal,Xconcentrationdecreasestoathird,isthevalueofninthereactionequation

A.3B.4C.5D.6

Solutionone:

grasp"theconcentrationofXdecreasesby1/3",thecoefficientratioofthecombinationofchemicalequationisequaltovolumeratio,canlistthebeginningstate,variableandfinalstateofeachsubstanceseparately:

4x3y2qnR

Theinitialstateis3L,2L,0,0

Variable-athird*3l=1l-3/4+2/4=3/4l*1*1ll=1/2l=n+n/4*1l/4l

Thefinalstateis3minus1isequalto2L2minus3/4isequalto5over4L0plus1/2isequalto1over2L0plusnover4isequaltonover4liters

Relationbyaboveknowable,balance（final）aftermixingthevolumeofagasof5/4（2++1/2+n/4）L（15+n）/4L,accordingtothequestion"thantheoriginalmixedgaspressureincreasedby5%（15+n）/4to5=5*5%,n=6areobtained.

Method2:

choosedifferencemethod,accordingtothequestionof"mixedgaspressurethantheoriginalincreasedby5%,"accordingtothequestion"thantheoriginalmixedgaspressureincreasedby5%,thevolumeofthemixedgasincreasesthe（2+3）*5%=0.25L,accordingtotheequation,4X+3ycanonlygenerate2q+nR,namelyevery4Xreactionvolume,totalvolumechangequantityforthe（2+n）-（4+3）=n-5,existing=1/3*3LLXreaction,namelythevolumechangeof1L*（n-5）/4=0.25L,soastocalculaten=6.

Method3:

seizethe"mixedgaspressurethantheoriginal5%increase",itisconcludedthatatthebeginningofthereactionbyX+Y,balancemustshifttotherightfirst,aftergeneratingQandR,thepressureincrease,showpositivereactioniscertainlyincreasethereactionvolume,thesumofthereactionequationcoefficientofXandYwillbelessthanthecoefficientofthesumofQandR,so4+3<2+n,itisconcludedthatthen>5,inthefouroptionsthataccordswitharequirementonlyDn=6,forthepersonstobetheanswer.

Subjecttestisaboutthecontentofthechemicalequilibrium.Asolutionistofollowthelawofchemicalequilibrium,asaccordingtothespecification,althoughcancertainlyworkoutthecorrectanswer,butdidnothold"choice,don'task,don'tprocess,aslongastheresults,thecharacteristicsofcalculatedasatopictodo,theordinarystudentalsoshoulduseatleast5minutestocomplete,spendmoretime.Methodusingdifferencemethod,withthevolumeofnvariables（delta）,toestablishtheequationfor豱RanXiaworkedoutthevalue,butstillfailedtomakefulluseofthe"choice"characteristicsofmultiplechoice,availabletoabout1minutes.Solutionthreeunderstandingontherelationshipbetweenthebalanceofmobileandvolumechange,nothalfaminutecanbeconcludedthattheonlycorrectanswer.

Thus,intheprocessofcalculationaccordingtothecharacteristicsofthesubjectchoosesdifferentproblemsolvingmethods,oftencouldhelpintheprocessofreducingoperationtimeandthechanceoferror,toachievefastandaccuratetheeffectofproblemsolving,andusemoreproblemsolvingmethodusuallyhasthefollowingkinds:

Quotientmethod:

thismethodisusedtosolvethemolecularweightoforganiccompounds（especiallyhydrocarbons）.

BecauseofalkanesgeneralformulaCnH2n+2,andthemolecularweightof14n+2,thecorrespondingparaffinbasegeneralformulaCnH2n+1,andthemolecularweightof14n+1,olefinsandnaphthenesgeneralformulaCnH2n,molecularweightof14n,thecorrespondingalkylthegeneralformulaCnH2n-1,themolecularweightof14n-1,alkynesandalkadienegeneralformulaCnH2n-2,molecularweightof14n2,correspondinghydroxylgeneralformulaCnH2n-3,themolecularweightof14n-3,socanbeknownmolecularweightminustheoxygen-containingfunctionalgroupsoftheorganicmattertypequantity,differencedividedby14（hydrocarbondirectlyinadditionto14）,isoneofthelargestbusinessforthenumberofcarbonatoms（i.e.,thevalueofn）,theremainderintothegeneralformula,andmolecularweightisofitsclass.

[example3]thetotalreactionofasinglechainofmonool14gramstoametalsodiumistogenerate0.2gramsofhydrogen.Theisomerofthisalcoholisthenumberofisomers

A.6B.7c.8d.9

Asoneyuanglycolcontainingonlyone-OH,permol,alcoholcanturnout1/2molh2,generatedbythe0.2gramsofH2infer14gramsofalcoholshouldbe0.2mol,sothemolecularweightof72grams/mo,themolecularweightof72,afterdeductingamountofhydroxytype17,remaining55,14,dividedbythebiggestdealerof3,13,isunreasonable,shouldtakebusinessfor4,to1,generationintothegeneralformula,andmolecularweightshouldbe4carbonolefinbaseornaphthenicbase,combinedwiththe"linear",soastodeducethenumberofisomersforsix.

2.Thisapproachismostsuitedtoqualitativelyaveragemethodisusedtosolvethecomponentsofthemixture,thepossibilityforthemixtureofingredients,withoutconsideringthecontentofeachcomponent.Accordingtothemixtureofvariousphysicalquantities（suchasdensity,volume,molecularweight,concentrationofamountofsubstance,suchasmassfraction）,thedefinitionofthetypeorsubjecttoconditions,mixturecancalculatetheaverageofcertainphysicalquantities,buttheaveragemustbebetweencompositionmixturebetweenthevariouscomponentsofthesamephysicalquantityvalue,inotherwords,themixtureofthetwocomponentsofthephysicalquantitymustbealargerthanaverage,asmallerthanaverage,tomeettherequirements,whichcandeterminethemixtureofmay.

[example4]amixtureoftwometallicmonomixturesof13g,whichwereaddedtothefullamountofdilutesulfuricacid,emits11.2Lofgasinthestandardcondition.Thetwometalsmaybe

A.ZnandFeB.AlandZnC.AlandMgd.mgandCu

MixtureasAkindofmetal,becauseisadequatedilutesulphuricacid,13gramsofallmetalreactiongenerated11.2L（0.5mole）areallhydrogengas,thatis,themetalmust26gramsperrelease1molehydrogen,ifallis+2valencemetal,itsaverageatomicweightis26,compriseAmixtureof+2valencemetal,itsatomicweightAgreaterthan26,Asmallerthan26.Thegenerationofselecteditems,inreplacementofthehydrogenreaction,+2pricewithzinc,atomicweightis65,Featomicweightis56,Mgatomicweightof24,butforAl,becauseinthereaction+3valence,toreplacethe1molhydrogen,aslongas18gramsofAlisenough,canbeseenasA+2pricesitsatomicweightis27/（3/2）=18,ifhavetheNa+1pricetoparticipateinthesamereaction,itwillbeconsideredA+2pricewhenitsatomicweightis23*2=46,forCu,becauseitcan'treplacetheH2,soastheatomicweightofinfinity,andgotanAinbothmetalatomicweightaremorethan26,Cintwokindsofmetalatomicweightarelessthan26,soA,doesnotmeettherequirements,CBAltheatomicweightofsmallerthan26,zincisgreaterthan26,DMginatomicweightissmallerthan26,Cuatomicweightisgreaterthan26,B,Dforthepersonstobetheanswer.

3.Limitmethod.Contrarylimitmethodandaveragemethod,thismethodisalsosuitableforthequalitativeorquantitativesolutionofmixturecomposition.Accordingtothemixtureofvariousphysicalquantities（suchasdensity,volume,molarmass,theamountofsubstanceconcentration,massfraction,etc.）thedefinitionofthetypeorsubjecttoconditions,themixtureasonlyoneofthecomponentA,namelythequalityscoreorgasvolumefractionis100%（maximum）,anothercomponentBorcorrespondingtothemassfractionofgasvolumefractionis0%（minimum）,canthevalueofoneofthecomponentsofAphysicalquantityN1,usingthesamemethodcanbecalculatedonlycontainBdoesnotcontainAmixtureofN2physicalquantitiesofthesamevalues,andthemixtureofthephysicalquantitiesNisaverage,mustbebetweenthemixtureofeachcomponentofA,B,betweenthesamequantityofnumericalnamelyN1

In[5]fourstudentsatthesametimeanalysisofamixtureofKClandKBr,theyallmatchintoaqueoussamplesfrom2.00grams,addenoughHNO3againafteraddingsuitableamountofAgNO3solution,afterbeingprecipitatedcompletelyfiltertogetthequalityoftheprecipitationofsilverhalidedryasshowninthefollowingfouroptions,ofwhichdataisreasonable

C.a.b.3.06g3.36g3.66gD.3.96

Subjectsuchasaccordingtothemethod,usuallymixturecontainingKClandKBr,canhaveaninfinitevarietyofways,thecalculateddataalsohasmanypossibilities,toverifythatthedataisreasonable,fouroptionsmustbeplugintoseeifthereisasolution,alsoisequivalenttofourquestionstodothemath,verymuch.Ittakestimetouselimitmethod,allsetto2.00gforKCl,accordingtoKCl-AgCl,every74.5gramsofKClcangenerate143.5gramsofAgCl,precipitationisavailablefor（2.00/74.5）*143.5=3.852grams,tothemaximum,thesamecanbeobtainedwhenthemixtureallforKBr,every119gramsofKBravailable