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1、高中化學(xué)58個精講(38)金屬的冶煉（58finelecturesonhighschoolchemistry(38)smeltingofmetals）Testsite38smeltingofmetals1.reviewthekeypoints1.thechemicalprincipleofmetalsmeltingandthebasicmethodofmetalsmelting;2.importantroleofmetalrecyclingandresourceprotection,The3.pointistoexaminethebasicmethodsofmetals
2、melting.2.difficultiesfocusFirst,theexistenceofmetalsinnature:1.freestateChemicallyinactivemetalscanexistasfreeforminnature,suchasAu,Ag,Pt,Cu2.chemicalcombinationChemicallyactivemetalsthatexistinnatureintheformofchemicalcompoundssuchasAl,NaExplanation:asmallnumberofmetalsexistinnatureinf
3、reeform,whilemostmetalsexistinacompositeforminnatureTwo.Smeltingofmetals:1.theessenceofmetalsmeltingThemetalcationinametalcompoundisreducedtoelectronsbyreductionMn++ne-=M2.majorstepsinmetalsmelting:OreenrichmentObjective:toremoveimpuritiesandincreasethecontentoftheusefulconstituentsofthe
4、ore;SmeltingObjective:toobtainmetallicsimplesubstancePrinciple:byusingtheprincipleofoxidation-reductionreaction,undercertainconditions,themetalioninmetaloreisreducedintometallicsinglesubstancebyreducingagentRefiningObjective:toimprovethepurityofmetals3.generalmethodsofmetalsmelting:Accor
5、dingtothelivelinessofmetals(1)thermaldecompositionmethod:Scopeofapplication:inactivemetalAg----AuSuchas:2Ag2O==4Ag+O2=2HgO==2Hg+O2=(2)reductionmethod:Scopeofapplication:morelivelymetalZn----CuSuchas:Fe2O3+3CO,==2Fe+3CO2Cr2O3+2Al==2Cr+Al2O3Commonlyusedreducingagents:C,CO,H2andactivemetals
6、,suchasaluminumThethermitreactionisalsoknownasthethermalreductionprocess[thinking]whatmethodshouldbeusedifthesmeltingofveryactivemetalscannotbereducedbythermalreduction?3.electrolysis:Scopeofapplication:livelymetalK-----AlSuchas:2Al2O3=4Al+3O2=+Cl2=2NaCl===2NaComparison:2NaCl+2H2O===2NaO
7、H=+Cl2=+H2=2CuSO4+2H2O===2Cu+2H2SO4+O2Electrolysisisalsousedintherefiningofsomeinertmetals[description]thedisadvantageofelectrolysisisthatitconsumesagreatdealofenergy,andthecostishigherThree,metalrecyclingandenvironmentalprotection1.significanceofmetalrecycling(1)tosavemi
