Monoprotic vs Polyprotic Acids
Acids tau txhais ntau txoj hauv kev los ntawm ntau tus kws tshawb fawb. Arrhenius txhais cov kua qaub ua ib yam khoom uas pub H3O+ ions hauv cov tshuaj. Bronsted- Lowry txhais lub hauv paus ua ib yam khoom uas tuaj yeem txais tau ib qho proton. Lewis acid txhais tau ntau dua li ob qho saum toj no. Raws li nws, txhua tus khub electron pub dawb yog lub hauv paus. Raws li lub Arrhenius los yog Bronsted-Lowry txhais, ib tug compound yuav tsum muaj ib tug hydrogen thiab muaj peev xwm los pub nws raws li ib tug proton los ua ib tug acid. Txawm li cas los xij, 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. Ib qho cawv tuaj yeem yog Bronsted-Lowry acid vim tias nws tuaj yeem pub cov proton tab sis, raws li Lewis, nws yuav yog lub hauv paus.
Txawm hais tias tsis hais cov ntsiab lus saum toj no, 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 zoo li HCl, HNO 3 yog ionized tag nrho hauv cov tshuaj kom muab cov protons. Cov acids tsis muaj zog xws li CH3COOH ib nrab dissociate 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.
Monoprotic Acid
Thaum ib lub molecule ntawm cov kua qaub dissociates nyob rau hauv ib tug aqueous tov, yog hais tias nws muab ib tug proton, ces cov kua qaub hais tias yog ib tug monoprotic acid. HCl thiab nitric acid (HNO3) yog qee qhov piv txwv rau monoprotic mineral acids. Hauv qab no yog qhov dissociation rau HCl nyob rau hauv aqueous nruab nrab muab ib tug proton.
HCl → H+ + Cl–
Lwm yam tshaj li cov ntxhia acid, tuaj yeem muaj monoprotic organic acids ib yam nkaus. Feem ntau thaum muaj ib pawg carboxylic, cov kua qaub yog monoprotic. Piv txwv li, acetic acid, benzoic acid, thiab ib qho yooj yim amino acid zoo li glycine yog monoprotic.
YPolyprotic Acid
Polyprotic acids muaj ntau dua ib lub atoms hydrogen, uas tuaj yeem pub dawb li protons thaum lawv yaj hauv qhov nruab nrab aqueous. Tshwj xeeb, yog tias lawv pub ob lub protons, peb hu lawv ua diprotic thiab, yog muab peb protons, triprotic, thiab lwm yam Hydrogen sulfide (H 2 S) thiab H 2 SO4 yog diprotic acids, uas muab ob lub protons. Phosphoric acid (H3PO4) yog triprotic acid. Feem ntau, polyprotic acids tsis tag nrho dissociate thiab muab tawm tag nrho cov protons ib txhij. Dissociation tas li rau txhua qhov kev sib cais sib txawv. Piv txwv li, hauv phosphoric thawj dissociation tas li yog 7.25 × 10 −3, uas yog tus nqi loj dua. Yog li tag nrho dissociation tshwm sim. Qhov thib ob dissociation tsis tu ncua yog 6.31 × 10 −8, thiab qhov thib peb yog 3.98 × 10 −13, uas yog qhov sib txawv tsawg dua li thawj tus.
Qhov txawv ntawm Monoprotic Acid thiab Polyprotic Acid yog dab tsi?
• Monoprotic tsuas yog muab ib qho proton los ntawm ib qho kua qaub molecule thaum dissociating hauv ib qho nruab nrab aqueous.
• Polyprotic txhais tau tias muab ntau lub protons los ntawm ib lub molecule.
