Bronsted vs Lewis
Acids thiab hauv paus yog ob lub ntsiab lus tseem ceeb hauv chemistry. Lawv muaj contradictory khoom. Peb ib txwm txheeb xyuas cov kua qaub ua tus pub dawb proton. Acids muaj qaub saj. Txiv qaub kua txiv, vinegar yog ob tug acids peb tuaj nyob rau hauv peb lub tsev. Lawv hnov mob nrog cov hauv paus ua dej, thiab lawv kuj hnov mob nrog hlau los ua H 2, yog li nce hlau corrosion. Cov kua qaub tuaj yeem muab faib ua ob, raws li lawv lub peev xwm los sib cais thiab tsim cov protons. Cov kua qaub muaj zog xws li HCl, HNO 3 yog ionized tag nrho hauv cov tshuaj kom muab cov protons. Cov acids tsis muaj zog xws li CH3COOH yog ib feem dissociates thiab muab tsawg dua ntawm cov protons. Ka yog cov kua qaub dissociation tas mus li. Nws muab ib qho kev qhia txog lub peev xwm los poob ib tug proton ntawm ib tug qaug zog acid. Txhawm rau xyuas seb cov khoom puas yog cov kua qaub lossis tsis yog, peb tuaj yeem siv ntau qhov ntsuas xws li litmus ntawv lossis pH ntawv. Hauv pH nplai, los ntawm 1-6 acids yog sawv cev. Cov kua qaub nrog pH 1 tau hais tias muaj zog heev, thiab raws li tus nqi pH nce, acidity poob qis. Ntxiv mus, acids tig xiav litmus rau liab.
Bases muaj cov xab npum nplawm zoo li kev xav thiab iab saj. Lawv hnov mob yooj yim nrog cov kua qaub ua dej thiab ntsev molecules. Caustic soda, ammonia, thiab ci dej qab zib yog qee yam ntawm cov hauv paus uas peb tuaj hla ntau zaus. Cov hauv paus tuaj yeem muab faib ua ob, raws li lawv lub peev xwm los cuam tshuam thiab tsim cov hydroxide ions. Lub hauv paus muaj zog zoo li NaOH thiab KOH yog tag nrho ionized hauv kev daws teeb meem los muab ions. Cov hauv paus tsis muaj zog xws li NH3 yog ib feem ntawm kev sib cais thiab muab cov hydroxide ions tsawg dua. Kb is the base dissociation constant. Nws muab ib qho kev qhia txog lub peev xwm poob hydroxide ions ntawm lub hauv paus tsis muaj zog. Cov kua qaub uas muaj pKa tus nqi (ntau tshaj 13) yog cov acids tsis muaj zog, tab sis lawv cov conjugate bases suav tias yog cov hauv paus muaj zog. Txhawm rau xyuas seb cov khoom puas yog lub hauv paus lossis tsis yog peb tuaj yeem siv ntau qhov ntsuas xws li litmus ntawv lossis pH ntawv. Bases qhia pH tus nqi siab dua 7, thiab nws hloov liab litmus rau xiav.
Lwm yam tshaj li cov yam ntxwv saum toj no peb tuaj yeem txheeb xyuas cov kua qaub thiab cov hauv paus raws li qee qhov nta. Cov kua qaub thiab cov hauv paus tau txhais ntau txoj hauv kev los ntawm ntau tus kws tshawb fawb xws li Bronsted, Lewis thiab Arrhenius.
Nyob zoo ib tsoom niam txiv kwv tij neej tsas sawv daws
Bronsted txhais lub hauv paus ua ib yam khoom uas tuaj yeem txais cov proton thiab cov kua qaub ua cov khoom uas tuaj yeem muab cov proton. Bronsted muab qhov kev xav no rau pem hauv ntej xyoo 1923. Tib lub sijhawm, Thomas Lowry tau nthuav tawm tib txoj kev xav. Yog li ntawd, qhov kev txhais no yog hu ua Bronsted-Lowry definition.
Lewis
Hauv xyoo 1923 Lewis tau tso nws txoj kev xav txog cov kua qaub thiab cov hauv paus. Nyob ntawd, nws piav qhia txog cov kua qaub li ib hom, uas lees txais ib khub electron. Lub hauv paus Lewis yog ib yam khoom uas tuaj yeem pub ib khub electron. Yog li, raws li Lewis, tuaj yeem muaj cov molecules, uas tsis muaj hydrogen, tab sis tuaj yeem ua raws li cov kua qaub. Piv txwv li, BCl3 yog Lewis acid, vim nws tuaj yeem txais ib khub electron. Thiab tseem molecules, uas tsis muaj hydroxides, tuaj yeem ua lub hauv paus. Piv txwv li, NH3 yog Lewis puag, vim tias nws tuaj yeem pub tus khub electron ntawm nitrogen.
Qhov txawv ntawm Bronsted thiab Lewis yog dab tsi?
• Bronsted txhais cov kua qaub raws li tus neeg pub khoom noj proton whereas Lewis txhais cov kua qaub ua ib qho khoom siv hluav taws xob.
• Raws li Bronsted txoj kev xav, lub hauv paus yog tus txais proton. Raws li Lewis txoj kev xav, lub hauv paus yog ib tus khub electron pub.
• Yog li ntawd, qee cov molecules, uas tsis muaj protons, tuaj yeem yog cov kua qaub raws li Lewis txoj kev xav.
