Oxides Amphoteric. meatotino vailaau, o se faagasologa mo le sauniaina

oxides Amphoteric (ua meatotino itulua) - i le tele o tulaga oxides uamea lea e maua maualalo electronegativity. E faalagolago i tulaga i fafo faaalia o so o se oxide acidic po o meatotino. O nei oxides ua faia e uʻamea suiga, lea e faaalia ai e masani nei setete oxidation: ll, lll, lV.

Faataitaiga o oxides amphoteric: oxide metala paʻepaʻe (ZnO), chromium lll oxide (Cr2O3), oxide alumini (Al2O3), oxide ll apa (SnO), oxide apa lV (SnO2), taitai ll oxide (PbO), taitai lV oxide (PbO2) , lV oxide titanium (TiO2), manganese oxide lV (MnO2), uʻamea lll oxide (Fe2O3), oxide beryllium (BeO).

O le tali masani o oxides amphoteric:

1. O nei oxides mafai ona tali atu ma le acids malosi. I lenei pepa o le masima o nei acids tasi. Tali o lenei ituaiga o se faaaliga o le meatotino a le ituaiga faavae. Mo se faataitaiga: ZnO (oxide metala paʻepaʻe) + H2SO4 (acid hydrochloric) → ZnSO4 (sulfate metala paʻepaʻe) + H2O (le vai).

2. I le tali i oxides amphoteric alkalis malosi, hydroxides faaalia meatotino acidic. I totonu o lenei duality o meatotino (i.e., amphoteric) ua faaalia i le faavaega o masima e lua.

I le liusuavai e tali i le masima alkali ua faia e le averesi e masani ai, mo se faataitaiga:
ZnO (metala paʻepaʻe oxide) + 2NaOH (Sodium hydroxide) → Na2ZnO2 (masani masima uiga) + H2O (le vai).
Al2O3 (alumina) + 2NaOH (hydroxide Sodium) = 2NaAlO2 + H2O (le vai).
2Al (Oi) 3 (alumini hydroxide) + 3SO3 (oxide teio) = Al2 (SO4) 3 (sulfate alumini) + 3H2O (le vai).

O le fofo oxides amphoteric e tali i alkali e fausia ai se masima lavelave, mo se faataitaiga: Al2O3 (alumina) + 2NaOH (Sodium hydroxide) + 3H2O (vai) + 2Na (Al (Oi) 4) (a masima faigata o tetragidroksoalyuminat sodium).

3. oxide uamea taitasi o so o se amphoteric se numera faamaopoopo. Mo se faataitaiga e metala paʻepaʻe (Zn) - 4, alumini (Al) - 4 po o le 6, mo chromium (CR) - 4 (seāseā) po o le 6.

4. oxide Amphoteric e le tali atu i le vai ma e mafai ona tatala ai.

A ni uiga faaalia faamaonia uamea amphoteric?

Matua tautala, e mafai ona faaalia se elemene amphoteric le meatotino a uma uʻamea ma nonmetals. O uiga vaega o lo o auai i totonu o le elemene o se vaega: Ia (beryllium), Ga (gallium), SAVALI (germanium), Sn (apa), Pb, Sb (antimony), laitiiti (bismuth), ma nisi, e pei foi o le toatele o le elemene B -groups - a CR (chromium), Mn (manganese), Fe (uʻamea), Zn (metala paʻepaʻe), Cd (cadmium), ma isi.

Tatou nei faamaonia le metala paʻepaʻe elemene vailaau amphoteric nei tali vailaau (Zn):

1. Zn (Oi) 2 (metala paʻepaʻe hydroxide) + N2O5 (dinitrogen pentoxide) = Zn (NO3) 2 (nitrate metala paʻepaʻe) + H2O (le vai).
ZnO (metala paʻepaʻe oxide) + 2HNO3 (acid nitric) = Zn (NO3) 2 (nitrate metala paʻepaʻe) + H2O (le vai).

b) Zn (Oi) 2 (hydroxide metala paʻepaʻe) + Na2O (oxide sodium) = Na2ZnO2 (sodium dioksotsinkat) + H2O (le vai).
ZnO (metala paʻepaʻe oxide) + 2NaOH (hydroxide Sodium) = Na2ZnO2 (sodium dioksotsinkat) + H2O (le vai).

I lena tulaga, pe afai o le elemene i le meatotino itulua o le lotoa ei ai le oxidation taua i lalo, o lona lua (amphoteric) meatotino e sili ona iloagofie ai le tupu i se laasaga oxidation vailauga.

E pei ona mafai ona chrome faataitaiga (CR). O lenei elemene ua setete oxidation nei: 3+, 2+ 6+. I le tulaga o le tolu meatotino faavae ma acidic ua faailoa mai pe tusa o le tutusa, ao y CR +2 meatotino faavae manumalo, ma i CR +6 - acid. O tali e faamaonia ai le saunoaga lenei:

CR + 2 → CrO (chromium oxide +2), CR (Oi) 2 → CrSO4;
CR + 3 → Cr2O3 (chromium oxide +3), CR (Oi) 3 (chromium hydroxide) → KCrO2 po sulphate chromium Cr2 (SO4) 3;
CR + 6 → CrO3 (chromium oxide +6), H2CrO4 → K2CrO4.

I le tele o tulaga oxides amphoteric o elemene vailaau i oxidation tulaga +3 ai i le pepa faatumu meta. E pei ona mafai ona taua faataitaiga: alumini oxide hydroxide (fua vailaau AlO (Oi) ma uʻamea metahydroxide (vailaau FeO (Oi) fuafaatatau) ...

E faapefea ona oxides amphoteric?

1. O le auala e sili ona talafeagai mo lo latou sauniuniga o le precipitation mai se fofo aqueous faaaogaina hydroxide ammonium, o se faavae vaivai. Mo se faataitaiga:
Al (NO3) 3 (alumini nitrate) + 3 (H2OxNH3) (aqueous fofo o amonia hydrate) = Al (Oi) 3 (oxide amphoteric) + 3NH4NO3 (tali o loo faatinoina i lalo o le vevela tikeri luasefulu).
Al (NO3) 3 (nitrate alumini) + 3 (H2OxNH3) (hydroxide ammonium aqueous) = AlO (Oi) (oxide amphoteric) + 3NH4NO3 + H2O (tali faia i le 80 ° C)

I le fesuiaiga tali o lenei ituaiga i le tulaga o alkali sili hydroxide alumini le a le precipitate. ua tatau ona totogi lenei i le mea moni e faapea o le alumini pasia i le anion ona o ana meatotino itulua: Al (Oi) 3 (alumini hydroxide) + OH- (sili alkali) = [Al (Oi) 4] - (anion hydroxide alumini).

Faataitaiga o lenei ituaiga o tali:
Al (NO3) 3 (alumini nitrate) + 4NaOH (hydroxide sodium sili) = 3NaNO3 + NA (Al (Oi) 4).
ZnSO4 (metala paʻepaʻe sulfate) + 4NaOH (hydroxide sodium sili) = Na2SO4 + Na2 (Zn (Oi) 4).

Masima ua faia i le taimi lava e tasi, e tuufaatasi lavelave. E aofia ai anions lavelave: (Al (Oi) 4) - ma isi (Zn (Oi) 4) 2-. O lea sa ou taʻua o le masima: NA (Al (Oi) 4) - tetragidroksoalyuminat sodium, Na2 (Zn (Oi) 4) - tetragidroksotsinkat sodium. Tali oloa o alumini po o le metala paʻepaʻe oxides ma le alkali mautu ua valaauina ese: NaAlO2 - sodium dioksoalyuminat ma Na2ZnO2 - dioksotsinkat sodium.