Qhov sib txawv tseem ceeb ntawm daim ntawv cog lus lub zog thiab daim ntawv cog lus sib koom lub zog yog tias lub zog cog lus yog tus nqi nruab nrab whereas daim ntawv cog lus lub zog yog tus nqi tshwj xeeb rau ib daim ntawv cog lus.
Raws li tau hais los ntawm American chemist G. N. Lewis, atoms ruaj khov thaum lawv muaj yim electrons hauv lawv lub plhaub valence. Feem ntau ntawm cov atoms muaj tsawg tshaj li yim electrons nyob rau hauv lawv valence shells (tshwj tsis yog cov noble gases nyob rau hauv pab pawg neeg 18 ntawm lub periodic rooj); yog li ntawd, lawv tsis ruaj khov. Yog li ntawd, cov atoms zoo li ua rau ib leeg, ua kom ruaj khov. Nws tuaj yeem tshwm sim los ntawm kev tsim cov ionic bonds, covalent bonds lossis metallic bonds nyob ntawm qhov electronegativity ntawm atoms. Thaum ob lub atoms zoo sib xws los yog tsawg heev electronegativity sib txawv, react ua ke, lawv tsim ib tug covalent daim ntawv cog lus los ntawm sib koom electrons. Bond zog thiab daim ntawv cog lus dissociation zog yog ob lub ntsiab lus hais txog covalent chemical bonds.
Bond Energy yog dab tsi?
Thaum daim ntawv cog lus tsim, qee lub zog tso tawm. Nyob rau hauv sib piv, daim ntawv cog lus tawg yuav tsum tau ib co nqi zog. Rau ib qho tshuaj lom neeg daim ntawv cog lus, lub zog no tsis tu ncua. Thiab peb muab nws lub npe raws li daim ntawv cog lus zog. Yog li, daim ntawv cog lus lub zog yog qhov kub uas yuav tsum tau ua kom tawg ib qho mole ntawm molecules rau hauv nws cov atoms sib xws.
Ntxiv mus, peb tuaj yeem soj ntsuam lub zog ntawm cov khoom siv tshuaj lom neeg hauv ntau hom xws li lub zog tshuaj, lub zog siv hluav taws xob lossis hluav taws xob. Txawm li cas los xij, thaum kawg, tag nrho cov zog no hloov mus ua cua sov. Yog li ntawd, peb tuaj yeem ntsuas qhov nyiaj tshuav ntawm lub zog hauv kilojoule lossis kilocalorie.
Daim duab 01: Bond Energy
Ntxiv mus, daim ntawv cog lus lub zog yog qhov qhia txog lub zog ntawm daim ntawv cog lus. Piv txwv li, daim ntawv cog lus muaj zog yog ib qho nyuaj rau cleave. Yog li ntawd, lub zog ntawm daim ntawv cog lus ntawm lawv yog loj dua. Ntawm qhov tod tes, cov ntawv cog lus tsis muaj zog muaj lub zog me me, thiab lawv yooj yim rau cleave. Bond zog kuj qhia txog qhov kev sib cog lus. Cov nyiaj qiv nyiaj siab dua txhais tau tias qhov nyiaj tshuav tsawg (yog li ntawd, daim ntawv cog lus muaj zog siab). Tsis tas li ntawd, thaum lub zog ntawm daim ntawv cog lus tsis tshua muaj kev sib raug zoo yog siab dua. Raws li tau hais nyob rau hauv kev taw qhia electronegativity plays ib feem nyob rau hauv daim ntawv cog lus. Yog li ntawd, lub electronegativity ntawm lub atoms kuj pab rau lub zog daim ntawv cog lus.
Bond Dissociation Energy yog dab tsi?
Bond dissociation zog kuj yog ib qho kev ntsuas ntawm daim ntawv cog lus lub zog. Peb tuaj yeem txhais tau tias nws yog qhov hloov pauv enthalpy tshwm sim thaum daim ntawv cog lus tau dhau los ntawm homolysis. Bond dissociation zog yog tshwj xeeb rau ib daim ntawv cog lus.
Nyob rau hauv rooj plaub no, tib daim ntawv cog lus tuaj yeem muaj cov nyiaj sib txawv sib txawv nyob ntawm qhov xwm txheej. Piv txwv li, muaj plaub C-H daim ntawv cog lus nyob rau hauv methane molecule, thiab tag nrho cov C-H daim ntawv cog lus tsis muaj tib daim ntawv cog lus dissociation zog.
Daim duab 02: Qee qhov Kev Sib Koom Tes Sib Koom Tes rau Kev Sib Koom Tes
Vim li no, nyob rau hauv cov methane molecule, daim ntawv cog lus dissociation zog rau C-H bonds yog 439 kJ / mol, 460 kJ / mol, 423 kJ / mol thiab 339 kJ / mol. Nws yog vim hais tias thawj daim ntawv cog lus breakage tsim ib hom radical ntawm homolysis, yog li thib ob daim ntawv cog lus breakage tshwm sim los ntawm ib tug radical hom, uas yuav tsum tau ntau zog uas thawj tus. Ib yam li ntawd, ib kauj ruam ntawm daim ntawv cog lus sib koom ua ke hloov pauv.
Qhov txawv ntawm Bond Energy thiab Bond Dissociation Energy yog dab tsi?
Bond zog yog qhov nruab nrab tus nqi ntawm cov roj-theem daim ntawv cog lus sib koom ua ke (feem ntau ntawm qhov kub ntawm 298 K) rau txhua daim ntawv cog lus ntawm tib hom hauv tib hom tshuaj. Txawm li cas los xij, daim ntawv cog lus lub zog thiab daim ntawv cog lus lub zog tsis sib xws. Bond dissociation zog yog tus qauv enthalpy hloov thaum ib daim ntawv cog lus covalent yog cleaved los ntawm homolysis muab fragments; uas feem ntau yog hom radical. Yog li ntawd, qhov sib txawv tseem ceeb ntawm daim ntawv cog lus lub zog thiab daim ntawv cog lus sib txuas lub zog yog qhov nyiaj cog lus lub zog yog tus nqi nruab nrab thaum lub zog sib koom ua ke yog tus nqi tshwj xeeb rau ib daim ntawv cog lus.
Piv txwv li, nyob rau hauv methane molecule, bond dissociation energies rau C-H bonds yog 439 kJ / mol, 460 kJ / mol, 423 kJ / mol thiab 339 kJ / mol. Txawm li cas los xij, lub zog ntawm C-H ntawm methane yog 414 kJ / mol, uas yog qhov nruab nrab ntawm tag nrho plaub qhov tseem ceeb. Tsis tas li ntawd, rau lub molecule, daim ntawv cog lus dissociation zog yuav tsis tas yuav sib npaug zos rau lub zog daim ntawv cog lus (raws li piv txwv saum toj no-muab methane). Rau lub diatomic molecule, daim ntawv cog lus lub zog thiab daim ntawv cog lus dissociation zog yog tib yam.
Hauv qab infographic ntawm qhov sib txawv ntawm daim ntawv cog lus lub zog thiab daim ntawv cog lus lub zog muab cov ntsiab lus ntxiv ntawm qhov sib txawv.
Summary – Bond Energy vs Bond Dissociation Energy
Bond dissociation zog txawv ntawm daim ntawv cog lus zog. Bond zog yog qhov nruab nrab tus nqi ntawm tag nrho cov nyiaj sib koom ua ke lub zog ntawm ib lub molecule. Li no, qhov sib txawv tseem ceeb ntawm daim ntawv cog lus lub zog thiab daim ntawv cog lus sib koom lub zog yog tias lub zog ntawm daim ntawv cog lus yog tus nqi nruab nrab thaum lub zog sib koom ua ke yog ib qho nqi tshwj xeeb rau ib daim ntawv cog lus.
