Amphoteric oxides. Kemikali-ini, a ilana fun ngbaradi

Amphoteric oxides (nini meji-ini) - ni ọpọlọpọ igba irin oxides eyi ti o ni kekere electronegativity. Ti o da lori ita awọn ipo han eyikeyi ekikan afẹfẹ tabi ini. Awọn wọnyi ni oxides ti wa ni akoso nipa orilede awọn irin, eyi ti ojo melo ti olohun awọn wọnyi ifoyina ipinle: Ll, lll, LV.

Apeere ti amphoteric oxides: sinkii afẹfẹ (ZnO), chromium afẹfẹ lll (Cr2O3), aluminiomu afẹfẹ (Al2O3), afẹfẹ Ll tin (SnO), tin afẹfẹ LV (SnO2), asiwaju afẹfẹ Ll (PbO), asiwaju afẹfẹ LV (PbO2) , titanium afẹfẹ LV (TiO2), manganese afẹfẹ LV (MnO2), irin ohun elo afẹfẹ lll (Fe2O3), beryllium afẹfẹ (BeO).

Awọn aati aṣoju ti amphoteric oxides:

1. Awọn wọnyi ni oxides le fesi pẹlu lagbara acids. Ni yi fọọmu awọn iyọ ti awọn wọnyi kanna acids. Aati ti yi iru ti wa ni a manifestation ti awọn-ini ti awọn ipilẹ iru. Fun apẹẹrẹ: ZnO (sinkii afẹfẹ) + H2SO4 (hydrochloric acid) → ZnSO4 (sinkii imi-ọjọ) + H2O (omi).

2. Ni awọn lenu pẹlu lagbara alkalis amphoteric oxides, hydroxides ti olohun ekikan-ini. Ni yi duality ti-ini (i.e., amphoteric) ti wa ni fi ni awọn Ibiyi ti meji iyọ.

Ni awọn yo nipa lenu pẹlu awọn alkali iyọ ti wa ni akoso ni apapọ deede, fun apẹẹrẹ:
ZnO (sinkii afẹfẹ) + 2NaOH (soda hydroxide) → Na2ZnO2 (deede tumosi iyo) + H2O (omi).
Al2O3 (alumina) + 2NaOH (soda hydroxide) = 2NaAlO2 + H2O (omi).
2Al (OH) 3 (aluminiomu hydroxide) + 3SO3 (efin afẹfẹ) = Al2 (SO4) 3 (aluminiomu imi-ọjọ) + 3H2O (omi).

Ojutu amphoteric oxides nipa lenu pẹlu alkali lati fẹlẹfẹlẹ kan ti eka iyọ, fun apẹẹrẹ: Al2O3 (alumina) + 2NaOH (soda hydroxide) + 3H2O (omi) + 2Na (Al (OH) 4) (a eka iyọ ti soda tetragidroksoalyuminat).

3. Kọọkan eyikeyi amphoteric irin afẹfẹ ni o ni a eto nọmba. Fun apẹẹrẹ to sinkii (Zn) - 4, aluminiomu (Al) - 4 tabi 6, fun chromium (Kr) - 4 (toje) tabi 6.

4. Amphoteric afẹfẹ ko ni fesi pẹlu omi ati ki o ko tu ninu rẹ.

Ohun ti aati mule amphoteric irin?

Jo soro, ohun amphoteric ano le fi han awọn ini ti awọn mejeeji awọn irin ati nonmetals. Iru iwa ẹya-ara ni bayi ni awọn eroja ti A ẹgbẹ: Jẹ (beryllium), Ga (gallium), Ge (Germanium), SN (tin), PB, SB (antimony), Bi (bismuth), ati diẹ ninu awọn miran, bi daradara bi ọpọlọpọ ninu awọn eroja B -groups - a Kr (chromium), Mi (manganese), Fe (irin), Zn (sinkii), CD (cadmium), ati awọn miran.

A bayi mule awọn wọnyi kemikali aati amphoteric kemikali ano sinkii (Zn):

1. Zn (OH) 2 (sinkii hydroxide) + N2O5 (dinitrogen pentoxide) = Zn (NO3) 2 (sinkii iyọ) + H2O (omi).
ZnO (sinkii afẹfẹ) + 2HNO3 (oyi acid) = Zn (NO3) 2 (sinkii iyọ) + H2O (omi).

b) Zn (OH) 2 (sinkii hydroxide) + Na2O (soda afẹfẹ) = Na2ZnO2 (soda dioksotsinkat) + H2O (omi).
ZnO (sinkii afẹfẹ) + 2NaOH (soda hydroxide) = Na2ZnO2 (soda dioksotsinkat) + H2O (omi).

Ni ti nla, ti o ba ni ano pẹlu awọn meji-ini ti awọn yellow ni o ni awọn wọnyi ifoyina, awọn oniwe-meji (amphoteric)-ini julọ ifiyesi waye ni ohun agbedemeji ifoyina igbese.

Bi apẹẹrẹ le ti wa ni Chrome (Kr). Yi ano ni o ni awọn wọnyi ifoyina ipinle: 3+, 2+ 6+. Ni awọn nla ti mẹta ipilẹ ati ekikan-ini ti wa ni kosile to se, nigba ti y Kr +2 ipilẹ-ini bori, ati ni Kr +6 - acid. Nibi ni o wa aati ti o mule yi gbólóhùn:

Cr + 2 → CrO (chromium afẹfẹ +2), Kr (OH) 2 → CrSO4;
Cr + 3 → Cr2O3 (chromium afẹfẹ +3), Kr (OH) 3 (chromium hydroxide) → KCrO2 tabi chromium sulphate Cr2 (SO4) 3;
Cr + 6 → CrO3 (chromium afẹfẹ +6), H2CrO4 → K2CrO4.

Ni ọpọlọpọ igba amphoteric oxides ti kemikali eroja ni ifoyina ipinle +3 tẹlẹ ninu awọn orisirisi fọọmu. Bi apẹẹrẹ le ti wa ni toka: Aluminiomu hydroxide afẹfẹ (kemikali agbekalẹ AlO (OH) ati irin metahydroxide (kemikali FeO (OH) agbekalẹ) ...

Bawo ni amphoteric oxides?

1. Awọn julọ rọrun ọna fun wọn igbaradi jẹ ojoriro lati ẹya olomi ojutu lilo ammonium hydroxide, ti o ni kan ko lagbara mimọ. Fun apẹẹrẹ:
Al (NO3) 3 (aluminiomu iyọ) + 3 (H2OxNH3) (olomi ojutu ti amonia hydrate) = Al (OH) 3 (amphoteric afẹfẹ) + 3NH4NO3 (lenu ti wa ni ošišẹ ti labẹ ooru ogún iwọn).
Al (NO3) 3 (aluminiomu iyọ) + 3 (H2OxNH3) (olomi ammonium hydroxide) = AlO (OH) (amphoteric afẹfẹ) + 3NH4NO3 + H2O (lenu ošišẹ ti ni 80 ° C)

Ni awọn paṣipaarọ lenu ti yi iru ninu ọran ti excess alkali aluminiomu hydroxide yoo ko ìṣokùnfa. Eleyi jẹ nitori si ni otitọ wipe awọn aluminiomu koja sinu anion nitori ti awọn oniwe meji-ini: Al (OH) 3 (aluminiomu hydroxide) + OH- (excess alkali) = [Al (OH) 4] - (aluminiomu hydroxide anion).

Apeere ti yi iru lenu:
Al (NO3) 3 (aluminiomu iyọ) + 4NaOH (excess soda hydroxide) = 3NaNO3 + Lori (Al (OH) 4).
ZnSO4 (sinkii imi-ọjọ) + 4NaOH (excess soda hydroxide) = Na2SO4 + Na2 (Zn (OH) 4).

Iyọ eyi ti wa ni akoso ni akoko kanna, ni o wa eka agbo. Wọn ti ni eka anions: (Al (OH) 4) - ati awọn miiran (Zn (OH) 4) 2-. Ki ni mo ti a npe ni iyo: Lori (Al (OH) 4) - soda tetragidroksoalyuminat, Na2 (Zn (OH) 4) - soda tetragidroksotsinkat. Lenu awọn ọja ti aluminiomu tabi sinkii oxides pẹlu awọn ri alkali wa ni a npe otooto: NaAlO2 - soda dioksoalyuminat ati Na2ZnO2 - soda dioksotsinkat.