Amphoteric oxides. Tshuaj zog, ib tug txheej txheem rau kev npaj

Amphoteric oxides (muaj dual zog) - nyob rau hauv feem ntau hlau oxides uas muaj tsawg electronegativity. Nyob rau sab nraud tej yam kev mob muaj tej acidic oxide los yog cov khoom. Cov oxides yog tsim los ntawm txoj kev hloov co, uas feem ntau muaj cov nram qab no oxidation xeev: ll, lll, LV.

Piv txwv ntawm amphoteric oxides: zinc oxide (ZnO), chromium oxide lll (Cr2O3), txhuas oxide (Al2O3), oxide ll tin (SnO), tin oxide LV (SnO2), ua oxide ll (PbO), ua oxide LV (PbO2) , titanium oxide LV (TiO2), manganese oxide LV (MnO2), hlau oxide lll (Fe2O3), beryllium oxide (BeO).

Lub tshua ntse amphoteric oxides:

1. Cov oxides yuav hnov mob nrog muaj zog acids. Nyob rau hauv daim ntawv no lub ntsev ntawm cov tib acids. Tshua ntawm no hom yog ib tug manifestation ntawm lub zog ntawm cov yooj yim hom. Piv txwv li: ZnO (zinc oxide) + H2SO4 (hydrochloric acid) → ZnSO4 (zinc sulfate) + H2O (dej).

2. Nyob rau hauv cov tshuaj tiv thaiv muaj zog alkalis amphoteric oxides, hydroxides muaj acidic zog. Nyob rau hauv no duality cov khoom (i.e., amphoteric) yog manifested nyob rau hauv lub tsim ntawm ob ntsev.

Nyob rau hauv lub qhuav los ntawm cov tshuaj tiv thaiv nrog lub alkali ntsev yog tsim qhov nruab nrab li qub, piv txwv li:
ZnO (zinc oxide) + 2NaOH (Sodium hydroxide) → Na2ZnO2 (qub mean ntsev) + H2O (dej).
Al2O3 (alumina) + 2NaOH (Sodium hydroxide) = 2NaAlO2 + H2O (dej).
2Al (OH) 3 (txhuas hydroxide) + 3SO3 (leej faj oxide) = Al2 (SO4) 3 (txhuas sulfate) + 3H2O (dej).

Cov tshuaj amphoteric oxides los ntawm cov tshuaj tiv thaiv nrog alkali tsim tau ib txoj ntsev, piv txwv li: Al2O3 (alumina) + 2NaOH (Sodium hydroxide) + 3H2O (dej) + 2Na (Al (OH) 4) (a complex ntsev ntawm sodium tetragidroksoalyuminat).

3. Txhua yam amphoteric hlau oxide muaj ib tug ua kom sib haum tooj. Piv txwv li mus zinc (ZN) - 4, txhuas (Al) - 4 los yog 6, rau chromium (Kr) - 4 (muaj tsawg heev) los yog 6.

4. Amphoteric oxide tsis hnov mob nrog dej thiab tsis yaj nyob rau ntawd.

Yuav ua li cas tshua pov thawj amphoteric hlau?

Kuj hais lus, ib tug amphoteric caij tej zaum yuav muaj cov khoom ntawm ob co thiab nonmetals. Tej yam ntxwv feature yog tam sim no nyob rau hauv lub ntsiab ntawm ib pab pawg: Nco (beryllium), Ga (gallium), GE (germanium), SN (tin), Pb, SB (antimony), ob (Bismuth), thiab ib co rau lwm tus, raws li zoo li ntau ntawm cov ntsiab B -groups - ib tug Cr (chromium), Mn (manganese), Fe (hlau), ZN (zinc), Cd (cadmium), thiab lwm tus neeg.

Peb tam sim no ua pov thawj rau cov nram qab no tshuaj tshua amphoteric tshuaj caij zinc (ZN):

1. ZN (OH) 2 (zinc hydroxide) + N2O5 (dinitrogen pentoxide) = ZN (NO3) 2 (zinc nitrate) + H2O (dej).
ZnO (zinc oxide) + 2HNO3 (nitric acid) = ZN (NO3) 2 (zinc nitrate) + H2O (dej).

b) ZN (OH) 2 (zinc hydroxide) + Na2O (sodium oxide) = Na2ZnO2 (sodium dioksotsinkat) + H2O (dej).
ZnO (zinc oxide) + 2NaOH (Sodium hydroxide) = Na2ZnO2 (sodium dioksotsinkat) + H2O (dej).

Nyob rau hauv cov ntaub ntawv uas, yog tias lub caij nrog lub dual thaj chaw ntawm lub compound muaj cov nram qab no oxidation, nws dual (amphoteric) khoom uas feem ntau noticeably tshwm sim nyob rau hauv ib nrab oxidation kauj ruam.

Ua piv txwv li yuav Chrome (Kr). Qhov no lub caij muaj cov nram qab oxidation xeev: 3+, 2+ 6+. Nyob rau hauv cov ntaub ntawv ntawm peb yooj yim thiab acidic khoom no qhia kwv yees li Attendance, thaum y Kr +2 yooj yim zog yeej, thiab nyob rau hauv Cr + 6 - acid. Ntawm no yog tshua uas ua pov thawj no daim ntawv qhia:

Kr + 2 → CrO (chromium oxide +2), Cr (OH) 2 → CrSO4;
Kr + 3 → Cr2O3 (chromium oxide +3), Cr (OH) 3 (chromium hydroxide) → KCrO2 los yog chromium sulphate CR2 (SO4) 3;
Kr + 6 → CrO3 (chromium oxide + 6), H2CrO4 → K2CrO4.

Nyob rau hauv feem ntau amphoteric oxides ntawm tshuaj ntsiab nyob rau hauv oxidation xeev +3 muaj nyob rau hauv lub meta daim ntawv. Ua piv txwv li yuav raug nplua: Aluminium hydroxide oxide (tshuaj mis alo (OH) thiab hlau metahydroxide (tshuaj FeO (OH) mis) ...

Yuav ua li cas yog amphoteric oxides?

1. Cov yooj yim tshaj plaws txoj kev rau lawv cov kev npaj yog nag lossis daus los ntawm ib tug aqueous tov siv ammonium hydroxide, uas yog ib tug tsis muaj zog puag. Piv txwv li:
Al (NO3) 3 (txhuas nitrate) + 3 (H2OxNH3) (aqueous tov ntawm ammonia hydrate) = Al (OH) 3 (amphoteric oxide) + 3NH4NO3 (cov tshuaj tiv thaiv yog ua nyob rau hauv tshav kub nees nkaum degrees).
Al (NO3) 3 (txhuas nitrate) + 3 (H2OxNH3) (aqueous ammonium hydroxide) = alo (OH) (amphoteric oxide) + 3NH4NO3 + H2O (cov tshuaj tiv thaiv ua nyob rau ntawm 80 ° C)

Nyob rau hauv cov kev pauv cov tshuaj tiv thaiv ntawm no hom nyob rau hauv cov ntaub ntawv ntawm tshaj alkali txhuas hydroxide yuav tsis precipitate. Qhov no yog vim lub fact tias lub txhuas kis mus rau hauv lub anion vim hais tias ntawm nws cov dual zog: Al (OH) 3 (txhuas hydroxide) + OH- (tshaj alkali) = [Al (OH) 4] - (txhuas hydroxide anion).

Piv txwv ntawm no hom ntawm cov tshuaj tiv thaiv:
Al (NO3) 3 (txhuas nitrate) + 4NaOH (tshaj sodium hydroxide) = 3NaNO3 + Na (Al (OH) 4).
ZnSO4 (zinc sulfate) + 4NaOH (tshaj sodium hydroxide) = Na2SO4 + Na2 (ZN (OH) 4).

Ntsev uas yog tsim nyob rau tib lub sij hawm, yog complex tebchaw. Lawv muaj xws li txoj anions: (Al (OH) 4) - thiab lwm (ZN (OH) 4) 2-. Li ntawd, kuv hu ua cov ntsev: Na (Al (OH) 4) - sodium tetragidroksoalyuminat, Na2 (ZN (OH) 4) - sodium tetragidroksotsinkat. Cov tshuaj tiv thaiv cov khoom ntawm txhuas los yog zinc oxides nrog cov khoom alkali yog hu ua sib txawv: NaAlO2 - sodium dioksoalyuminat thiab Na2ZnO2 - sodium dioksotsinkat.