Amphoteric hydroxides - lub dual xwm ntawm qhov teeb meem

Muaj hydroxides uas hnov mob nrog acids thiab bases, nyob ntawm seb tus mob. Cov tebchaw seeb dual xwm yog hu ua amphoteric hydroxides. Lawv tsim los ntawm cov hlau ntawv thiab cov hydroxide ion, raws li zoo raws li tag nrho cov kev bases. Lub peev xwm ua raws li acids thiab bases muaj tsuas yog cov hydroxides uas muaj nyob rau hauv lawv cov muaj pes tsawg leeg xws co :. Yuav, ZN, Al, Pb, sn, Ga, Cd, Fe, Cr (III), etc. Raws li pom los ntawm cov Periodic System D. I. Mendeleyev, hydroxides tsim tau ib cov dual xwm co uas yog ze tshaj rau tus uas tsis yog-hlau. Nws yog ntseeg hais tias xws ntsiab yog txoj kev hloov mus cov ntaub ntawv, thiab division rau co thiab nonmetals es arbitrary.

Amphoteric hydroxides yog khoom hmoov finely crystalline tshuaj uas yog feem ntau dawb coloration tsis yaj nyob rau hauv dej thiab me ntsis conductive (tsis muaj zog electrolytes). Txawm li cas los, ib co ntawm cov bases yuav ua neej nyob rau hauv acids thiab alkalis. Dissociation "dual sib txuas" nyob rau hauv aqueous lub ntsiab tshwm sim los ntawm acid-puag hom. Qhov no yog vim lub fact tias cov tuav quab yuam ntawm cov hlau atoms thiab oxygen (kuv- D) ntawm cov pa thiab hydrogen atoms thiab (G - H) yog yuav luag sib npaug, i.e. Kuv - O - N. Yog li ntawd, cov bonds yuav tawg nyob rau tib lub sij hawm, thiab cov tshuaj -dissotsiirovat cations H + thiab OH- anions.

Paub meej tias lub dual xwm ntawm cov tebchaw yuav amphoteric hydroxide - Nco (OH) _2. Xav txog cov kev sis raug zoo ntawm beryllium hydroxide nrog ib tug acid thiab ib lub hauv paus.

1. Yuav tsum (OH) ₂ + 2HCl -BeCl ₂ + 2H ₂ O.

2. Nco (OH) ₂ + 2KOH - K ₂ [Nco (OH) _4] - tetragidroksoberillat poov tshuaj.

Nyob rau hauv thawj cov ntaub ntawv, cov neutralization cov tshuaj tiv thaiv yuav siv sij hawm qhov chaw, qhov tshwm sim ntawm uas yog lub tsim ntawm ntsev thiab dej. Nyob rau hauv lub thib ob cov ntaub ntawv, cov tshuaj tiv thaiv cov khoom no yog ib tug complex compound. Neutralization cov tshuaj tiv thaiv yog raug rau tag nrho cov, tsis muaj kev zam, hydroxides, tab sis tus sis zoo li cov yam ntxwv tsuas yog rau cov amphoteric. Tej dual zog yog manifest thiab lwm yam amphoteric compound - hlau oxides lawv tus kheej, lawv yog tsim nyob rau.

Lwm yam tshuaj thaj chaw ntawm xws hydroxides yog cov yam ntxwv ntawm tag nrho cov kev bases:

1. Thermal decomposition, cov tshuaj tiv thaiv khoom - sib nug xov oxide thiab dej: Nco (OH) ₂ -VeO + H ₂ O.

2. Cov neutralization cov tshuaj tiv thaiv nrog acids.

3. Cov tshuaj tiv thaiv nrog acidic oxides.

Nws tseem yog tsim nyog yuav tau nco ntsoov hais tias muaj tej yam tshuaj uas tsis INTERACTIONS amphoteric hydroxides, i.e. ib tug tshuaj cov tshuaj tiv thaiv tsis mus, nws yog:

1. uas tsis yog-hlau;
2. co;
3. insoluble puag;
4. Amphoteric hydroxides.
5. nruab nrab ntsev.

Cov tebchaw yog tau los ntawm precipitating lub sib nug xov alkali ntsev ntsiab:

BeCl ₂ 2KOH + - Nco (OH) ₂ + 2KCl.

Ntsev ntawm tej ntsiab thaum lub sij hawm cov tshuaj tiv thaiv tsim tau ib hydrate, cov khoom uas zoo raws li nram no hais tias ntawm lub dual xwm ntawm hydroxides. Lawv tus kheej nrog lub dual zog ntawm lub hauv paus ib feem ntawm cov zaub mov nyob rau hauv daim ntawv thiab uas tshwm sim lawm (bauxite, goethite, etc.).

Yog li, amphoteric hydroxides - ib tug mineral tshuaj, uas nyob rau qhov xwm ntawm tus tshuaj uas nkag mus rau lawv nyob rau hauv cov tshuaj tiv thaiv, yuav ua raws li bases los yog acids. Feem ntau cov feem ntau lawv sib amphoteric oxides muaj coj hlau (ZnO-ZN (OH) _2; BeO - Nco (OH) _2), thiab lwm yam).