高中化学考试注意点.docx
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高中化学考试注意点.docx
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高中化学考试注意点
高中化学考试注意点(Attentionshouldbepaidtohighschoolchemistryexamination)
Findtheeyeproblemonthebasisof"
1.eyeone:
commongas
Simplegas:
H2,O2,N2,Cl2(HuangLvshai)andF2(palegreen)
Gaseoushydride:
NH3(redlitmuspapercolorless,pungentodor,easilyliquefied,easilysolubleinwater,canmakewetblue,metHClformationofwhitesmoke)
HCl(bluelitmuspapercolorless,pungentodor,easilysolubleinwater,canmakethemoistred,theformationofwhitemist,intheairencounteredintheNH3formationofwhitesmoke)
H2S(colorlessandodorouseggsmell,proteindecayproduct,solubleinwater,canleadtoawetleadacidtestblack)
Ahydrocarbonof4orlessthan4carbon
Nonmetallicgasoxide:
CO,CO2(linearnonpolarmolecules),NO(whichturnsredintheair),NO2(redbrown,pressurized,cooldown)intocolorless,andSO2(colorlessandpungentodorthatcandiscolormagentasolution)
[solidoxide]:
SO3(colorlesscrystal,YiHuifa)andP2O5(whitesolid,easilyhygroscopic,oftenusedasadesiccant),SiO2(insolubleinwater,highmeltingsolidsinsolubleinordinaryacids,butsolubleinhydrofluoricacidandalkalisolution)
Gaseoushalogenatedhydrocarbons:
methylchloride(CH3Cl)andvinylchloride(CH2=CHCl)
Gaseousaldehydes:
formaldehyde(HCHO)
2.eyetwo:
gassolubilityinduction
Insolubleinwater:
H2,N2,CO,NO,CH4,C2H4;
Slightlysolubleinwater:
O2,C2H2;
Solubleinwater:
Cl2(1:
1),H2S(1:
2.6),SO2(1:
40);
Highlysolubleinwater:
NH3(1:
700),HCl(1:
500),HF,HBr,HI.
3.eyethree:
commonliquidsubstances
Inorganic:
Br2,brominewater(H2O),hydrogenperoxide(H2O2),carbondisulfide(CS2),phosphorus(PCl3)
Aninferiorhydrocarbonofmorethan5carbonatoms;
Inadditiontolowermethanechlorideandvinylchlorideadditionofhalogenatedhydrocarbons;
Loweralcohol;
Lowaldehydesotherthanformaldehyde;
Lowercarboxylicacid;
Low-gradeester.
4.eyefour:
thecolorofcommonsubstances
Red:
Fe(SCN)3(Xueredsolution);Cu2O(Zhuanredsolid);Fe2O3(reddishbrownsolid);
Red(darkredsolid);bromine(darkredbrown);Fe(OH)3(redbrownsolid);
Cu(purplishredsolid);brominevapor,NO2(reddishbrown)magentasolution(red);
Thephenolintheairforalongtime(FenHong);acidicsolution(litmusred);phenolphthaleinalkalinesolution(red).
Violet:
Litmusneutralsolution(purple);Fe3+andphenolreactionproducts(purple);I2(metallicpurplesolid)
KMnO4solid(purpleblack);MnO4-(violetredsolution)solidO3(purpleblack)
TheflamereactionofpotassiumvaporI2(purple)andI2innonpolarsolvents(purple)
Orange:
water(Orange)K2Cr2O7solution(Orange)
Yellow:
AgI(yellowsolid);AgBr(paleyellowsolid);Ag3PO4(yellowsolid);FeS2(yellowsolid);
Na2O2(paleyellowsolid);S(yellowsolid);Au(metallicluster,yellowsolid);
TheaqueoussolutionofI2(yellow);iodine(HuangHeshai);alongsetofKIsolution(yellow)(oxidizedI2);
TheflameofNa(yellow);TNT(paleyellowneedle);industrialhydrochloricacidcontainingFe3+(yellow);
NaNO2(colorlessorlightyellowcrystal);aqueoussolutionofFe3+(yellow);
Whennitrobenzeneisdissolvedinconcentratednitricacid,NO2(yellow)isdecomposed
Longconcentratednitricacid(yellow)(solubleNO2producedbydecomposition);
Concentratednitricacidontotheskin(naturalprotein)(pronouncedyellow);
Green:
Cu2(OH)2CO3(greensolid);theaqueoussolutionofFe2+(lightgreen);FeSO47H2O(green);
K2MnO4(green);Cl2;F2(HuangLvshai),chlorine(yellowgreen);
TheconcentratedsolutionofCuCl2(blue-green);
Brown:
FeCl3solid(brownishyellow);
CuCl2solid(brown)
Blue:
Cu(OH)2,CuSO4,5H2O,Cu2+inaqueoussolution(blue)inalkalinesolution;litmus(blue);
Sulfur,hydrogen,methane,andethanolburnintheair(paleblueflames);carbonmonoxideburnsintheair(blueflame);
StarchturnsblueinI2;Co2O3(blue);O2(liquid-lightblue);
Cu(OH)2solublepolyhydroxycompounds(suchasglycerolandglucose)inaqueoussolution(deepblue);
O3(gaseous-lightblue;liquid-darkblue;solidvioletblack).
Black:
FeO;Fe3O4;FeS;CuO;CuS;Cu2S;MnO2;Cpowder;
Ag2S,Ag2O,PbS,AgCl,AgBr,AgIandAgNO3weredarkenedbyilluminationdecomposition;
Mostmetalsareblackorblackinpowderstate.
White:
commonwhitesolidmaterialisasfollows(whiteorcolorlesssolid,crystalalot):
AgCl;Ag2CO3;Ag2SO4;Ag2SO3;BaCO3;BaSO4;BaSO3;
Ba3(PO4)2;BaHPO4;CaO;Ca(OH)2;CaCO3;MgO;Mg(OH);
MgCO3;Fe(OH)2;AgOH;PCl5;SO3;CuSO4tribromophenol
Ammoniumsalt(whitesolidorcolorlesscrystal);
Fe(OH)2precipitatesintheair:
whitetofast(gray),greento(eventually)reddishbrown
PHtestpaper:
yellowwhenitisdry;neutralgreen;whenacidisred,acidityisstronger;redisdeeper;alkalineisblue;alkalineisstronger;blueisdeeper.
Red:
redlitmuspaper(usedtotestalkalinesubstances):
bluelitmuspaperblue(fortestingacid)
Starchtestpaper:
White(usedtotestiodine),KI-starchtestpaper:
White(usedtotestoxidizingsubstances)
Litmus:
pH<5red;pHrangedfrom5~8purple;pH>8isblue.
Phenolphthalein:
pH<8.2pHwascolorless;between8.2~10pink;pH>10isred.
MethylOrange:
redwhenpH<3.1;pHbetween3.1and4.4isorange;pH>4.4isyellow.
Methylred:
pH<4.4isred;pHbetween4.4and6.2isorange;pH>6.2isyellow.
5.questions:
fiveeyediagramaccordingtothechangeofthesameelementvalenceasthemainline,namelyA,B,C......Typeinduction
CCOCO2;H,2S,S,SO2,SO3(H2SO4);
NH3(N2)NONO2HNO3;NaNa2ONa2O2;
Fe,FeO,Fe3O4;Fe=Fe2+=Fe(OH)2,Fe(OH)3;
Fe=Fe2+=Fe3+;Cl-Cl2ClO-;
Acid-basereaction.
CH2=CH2CH3CHOCH3COOH;CH3CH2OHCH3CHOCH3COOH
6.eyesix:
accordingtotheformofchemicalreaction
A.makesinferencesbasedonthereplacementreaction,"simplematter+compound=newsubstance+newcompound"
1,metaldisplacementmetal
(1)replacementbetweentheactivemetalelementsandtheinactivemetalcations;
NM+mNn++mNm+==nM
(2)thermitreaction
Highmeltingpointmetaloxides(suchasFe3O4,Fe2O3,FeO,WO3,V2O5,MnO2,CrO3etc.)andaluminumpowdermixturecalledthermite,needhightemperatureconditionstoinitiatethereactionoccurs,usuallyusedforsmeltingofhighmeltingpointmetal.Suchas:
10Al+3V2O5,5Al2O3+6V,8Al+3Fe3O4,4Al2O3+9Fe
(3)theuseofmetalmetalreplacementofLeChatelier'sprincipleseeeighteen,1
(2)]
2,metalreplacementofnon-metallic
(1)themetalreactswithwatertodisplacetheH2
2Na+2H2O=2Na++2OH+H2-(=veryactivemetalreactionwithH2Oatroomtemperature)
Mg+2H2OMg(OH)2+(H2=H2Oactivemetalandobviousreactionwhenheated)
3Fe+4H2O+4H2=Fe3O4(theproductionofmetaloxidesandH2reactionmediumactivemetalandH2Ounderhightemperatureconditions)
(2)themetalreactswithnonoxidizingacidtodisplaceH2
2Al+6H+=2Al3++3H2=Fe+2H++H2===Fe2+
Zn+2CH3COOH=Zn2++2CH3COO+H2=-
Topayattentionto:
ThemetalinfrontofHintheorderofmetalactivitycanbereplacedbyH+intheacidtoH2.
Thenonoxidizingacidreferstoacidelementsnotsignificantoxidizingacid,suchashydrochloricacid,dilutesulfuricacid,phosphoricacid,aceticacid;oxidativeacidreferstoacidelementswereoxidizingacid,suchasSelements,sulfuricacidconcentration(diluted)+6price+5priceofNelements,nitrateinthehypochlorite+1priceClelementetc..Theoxidationofacids,includingtheoxidationofH+oracidelementsinacids.Allacidshaveacertaindegreeofoxidation,becauseacidscontainH+.
ThesubstitutionreactionofFewithnonoxidizingacidorsomesaltsolutionistoproduce+2valenceironsalt;intheelectrodereaction,theelementalironalsolosestwoelectronsandformsferrousion.
ThereactionbetweenPbanddiluteH2SO4isoftenunabletocontinuebecausetheresultingPbSO4isinsolubleinwaterandcoversthesurfaceofthemetalPb,preventingthereactionfromcontinuing.
(3)metalreactswithalcoholanddisplacesH2
Suchas:
2Na,2C2H5OH+2C2H5ONa+H2=
(4)thereactionbetweenmetalandphenolwasreplacedbyH2
Suchas:
2Na++,H2=(melting)
(5)themetalreactswiththealkalisolutiontodisplacetheH2
2Al+2NaOH+2H2O+[Zn+2NaAlO2=3H2=2NaOH=Na2ZnO2+H2=]
Topayattentionto:
ThenatureofthereactionisAlandH2OreactedweaklyAl(OH)3[difficulttodissolveinwater,coveredonthesurfaceofAlandpreventthereactiontoproceedwithH2,butAl(OH)3istheamphoterichydroxidesolubleinalkalisolution,NaOH,AlandH2OcontinuetogenerateH2reactiontherefore,thereactionofH2OoxidanthydrogeninH2areallfromH2O.
3E*2
2Al+2NaOH+6H2O+3H2+4H2O===2NaAlO2
ThereactionprincipleofZnwithalkalisolutionisthesameasabove.
(6)themetaldisplacesothernonmetallicelements
Suchas:
2Mg+CO2,2MgO+C(producealotofwhitesmoke,thereisasmallamountofblacksolidonthebottlewall)
2Mg+SO2,2MgO+,Sor3Mg+SO2,2MgO+MgS
3non-metallicreplacementofnon-metallic
(1)nonmetallicelementsareusedasoxidizingagents
Suchas:
I2+S2+S==2I-2F2+2H2O=4HF+:
O2
2FeBr2+3Cl2+2Br2+3Br2==2FeCl32FeI2=2FeBr3+2I2
(Cl2excess)(Br2excess)
[6FeBr2+3Cl2+4FeBr3]+Br2==2FeCl3FeI2=FeBr2+I2
(Cl2small)(Br2small)
Explanation:
theorderofstrengthofreductionis:
S2>I>Fe2+>Br-soCl2firstoxidizeI-thenoxidizeFe2+,andfinallyoxidizeBr-.
X2+H2S=2H++2X+S(X2=Cl2,Br2:
I2)
2H2S+O2(insufficient)2S+2H2O(H2Sincompletecombustioninair)
2H2S+O2=2S+2H2O(lowermetamorphichydrogensulfateintheairforalongtime)
3Cl2+2NH3+N2+8NH3==6HCl3Cl2=6NH4Cl+N2(excess)
(2
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