Al3+, Cr3+, Zn2+, As3+, Sn2+, AsV, SnIV.
, .
:
Al3+ − [Ne]; Cr3+ − [Ar]3d3; Zn2+ − [Ar]3d10; As3+ − [Ar]4s23d10; Sn2+ −
[Kr]5s24d10.
NaOH .
䳿 :
Al3+ + 3OH → Al(OH)3↓; Zn2+ + 2OH → Zn(OH)2↓;
Cr3+ + 3OH → Cr(OH)3↓; Sn2+ + 2OH → Sn(OH)2↓ .
ó , , , () - .
. :
Al(OH)3 + 3H+ → Al3+ + 32;
Cr(OH)3 + 3H+ → Cr3+ + 32;
Zn(OH)2 + 2H+ → Zn2+ + 22;
Sn(OH)2 + 2H+ → Sn2+ + 22.
( ) :
Al(OH)3 + 3OH → [Al(OH)6]3;
Cr(OH)3 + 3OH → [Cr(OH)6]3;
Zn(OH)2 + 2OH → [Zn(OH)4]2;
Sn(OH)2 + 2OH → [Sn(OH)4]2.
, :
[Al(OH)6]3 → Al2 + 22 + 2;
-
[Cr(OH)6]3 → Cr2 + 22 + 2;
-
[Zn(OH)4]2 → Zn22 + 22;
-
[Sn(OH)4]2 → Sn22 + 22.
-
:
Cr2− → Al2− → Zn22 → Sn22 → As43.
, , . , . () :
Cr2− + 22 → Cr(OH)3↓ + OH−.
Al2− , Cr2−. :
Al2− + NH4+ + 22 → Al(OH)3↓ + NH4OH.
, , , ; , , , .
, Cr(OH)3 Zn2+ Cr2(ZnO2)3 ( Cr2O33ZnO).
() , ͳ, .
ͳ Cr3+, Zn2+ 䳿 . Cr3+ Zn2+ , 䳿 , . Cr3+ Ni2+, Cr3+ 2+.
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Al(OH)3, Fe(OH)3 AlOH(CH3COO)2, FeOH(CH3COO)2 Cr(OH)3, () 䳿 .
, Cr3+ () , , :
2Cr3+ + 3Zn2+ +12− → Cr2(ZnO2)3↓ + 6H2O;
2Cr3+ + 32+ +8− → C3(CrO2)2↓ + 4H2O;
2Al(OH)3 + 2Cr(OH)3 → Al2O3Cr2O3↓ + 6H2O;
CH3COO− + H2O → CH3COO + − ();
CH3COO + 12− + 2Cr3+ + 3Zn2+ → Cr2(ZnO2)3↓ + 6H2O + CH3COO.
Cr3+ Zn2+ . 䳿 , , , , , Cr3+, Zn2+. , , .
ij , Cr3+, Al3+, Sn2+ , Zn2+, As3+ AsV [Zn(NH3)4]2+ AsO33 AsO43.
䳿 , , , , Zn2+; , Cr3+.
Zn2+ . Zn2+ Cr(OH)3.
Na2CO3, K2CO3, (NH4)2CO3 Al3+, Cr3+, Sn2+ SnIV , Zn2+ . As3+ AsV .
2Zn2+ + CO32 + 22 → Zn2()2CO3↓ + 2+;
2Al3+ + 3CO32 + 32 → 2Al(OH)3↓ + 3CO2;
2Cr3+ + 3CO32 + 32 → 2Cr(OH)3↓ + 3CO2;
Sn2+ + CO32 + 2 → Sn(OH)2↓ + CO2;
Sn4+ + 2CO32 + 22 → Sn(OH)4↓ + 2CO2.
NH4Cl.
Pb2+ , :
Pb2+ + 2− → Pb(OH)2↓;
Pb(OH)2 + 2NaOH → Na2[Pb(OH)4] .
Pb(OH)2 , Al(OH)3, Cr(OH)3, Zn(OH)2, Sn(OH)2.
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Pb2+, .
Sb3+ :
Sb3+ + 3 → Sb(OH)3↓;
Sb(OH)3 + NaOH → NaSbO2 + 2H2O.
. . SnIV AsV Sn4+, As5+ ( ). , AsO43 AsO33:
Sn2+ + 2H2O → Sn(OH)2↓ + 2H+;
As5+ + 4H2O → AsO43 + 8H+.
, : , 䳺 , :
Al2(CO3)3 +3H2O → 2Al(OH)3↓ + 3CO2↑;
2ZnCO3 + H2O → (ZnOH)2CO3 + CO2↑.
ϳ 䳺 Al3+, Cr3+, Zn2+, Sn2+ . Zn(OH)2 :
Zn(OH)2 + 4NH3H2O → [Zn(NH3)4](OH)2 + 4H2O.
䳿 , Al3+, Cr3+, Zn2+ - - , Sn2+ Sn(OH)2; As3+ As5+ :
Cr3+ + 2HPO42 → CrPO4↓+ H2PO4−;
3Sn2+ + 4HPO42 → Sn3(PO4)2↓+ 2H2PO4.
Sn3(PO4)2 :
Sn3(PO4)2 + 6H2O → 3Sn(OH)2 + 2H3PO4;
3Zn2+ + 4HPO42 → Zn3(PO4)2↓+ 2H2PO4−;
Al3+ + 2HPO42 → AlPO4↓+ H2PO4−.
, CrPO4 AlPO4 .
䳿 () () () () :
3Zn2+ + 24[Fe(CN)6] → Zn32[Fe(CN)6]2↓+ 6K+;
3Zn2+ + 23[Fe(CN)6] → Zn3[Fe(CN)6]2↓+ 6K+;
Sn(OH)2:
2Sn2+ + 4[Fe(CN)6] + 4H2O → 2Sn(OH)2↓ + H4[Fe(CN)6] + 4K+.
- () () , Zn2+ 4[Fe(CN)6] 3[Fe(CN)6] Zn2+.
Al3+ Cr3+ :
2Al3+ + 3(NH4)2S → Al2S3 + 6NH4+;
2Cr3+ + 3(NH4)2S → Cr2S3 + 6NH4+.
:
Al2S3 + 6H2O 2Al()3↓ + 3H2S;
Cr2S3 + 6H2O 2Cr()3↓ + 3H2S.
Zn2+ - ZnS , :
Zn2+ + H2S + 23− → ZnS↓ + 23H.
, As3+ As5+ AsO33 AsO43. As3+ As5+. :
AsO33 + 6+ → As3+ + 3H2O;
AsO43 + 8+ → As5+ + 4H2O.
:
2As3+ + 3H2S → As2S3↓+ 6+;
2As5+ + 5H2S → As2S3↓+ 2S↓ + 10+.
As2S3 - .
H2S Sn2+ SnIV. 4+ Sn4+:
Sn2+ + H2S → SnS↓+ 2+;
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Sn4+ + 2H2S → SnS2↓+ 4+.
SnS , SnS2 -.
4.5.1. Al3+
1. 䳿 , Al3+, :
AlCl3 + 3NH4OH → Al(OH)3↓+ 3NH4Cl.
. , AlO2− Al3+ 䳺 :
AlO2− + 4H+ → Al3+ + 2H2.
2. Al(OH)3 (, S-) , :
Al3+ .
1-2 , 1-2. ( ). Al3+ Al(OH)3. , - . , -, - . Cr3+, Zn2+, Sn2+, Fe3+ Al3+ . Al3+ : K4[Fe(CN)6], Al3+ . ϳ , , . Zn, Sn Cr3+, Al3+ .
, Al3+ Al(OH)3. , , , . Al3+ , , - .
Al3+ , . Cr3+, Zn2+, Sn2+ : Cr3+ , Zn2+ ,
Sn2+ , SnIV . Al3+ , Al3+. Al3+ .
, , , Al3+. , , Fe3+ - , Ba2+, Sr2+, Ca2+, Sb3+, Bi3+, Cu2+ , Cd2+ - . , Ni2+, Mn2+, Mg2+, Pb2+, Ag+, Hg2+.
3. 䳿 , Al3+, , . :
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3-5
, 2-3 (( 3)=2,0/3) 4-5 (w=0,1%). , , , 3-4 (( (N4)23=2,0/3). Al3+ , Al3+ .
4. Al3+ .
Al3+ , 1-2 (( (N3)2)=0,05/3). 쒿 . Al3+ :
2Al2(SO4)3 + 2 (N3)2 → 2Co(AlO2)2 + 6SO3↑ +4NO2↑ + O2↑.
.
Zn2+, Cr3+, Cu2+, Ni2+, .
5. Al3+ ≈4,5 8-. , , .
Al3+- Fe2+-. Fe3+- ≈2,0, . Al3+- Bi3+, Ni2+, Zn2+, Mg2+.
4.5.2. Cr3+
1. 䳿 Cr3+ () - :
Cr3+ + 3NH4OH → Cr(OH)3↓ + 3NH4+.
2. Cr3+ Cr(OH)3:
Cr3+ + 3OH → Cr(OH)3↓.
Cr(OH)3 :
Cr(OH)3 + OH− → [Cr(OH)4]− | CrO2−. |
- CrO2− - .
NaCrO2, NaAlO2, () :
CrO2− + 22 → Cr(OH)3↓ + OH−.
.
3. 䳿 , Cr3+, Zn2+ , :
2CrCl3 + 3ZnCl2 + 12NaOH → Cr2(ZnO2)3↓ + 12NaCl + 6H2O.
4. Cr3+ .
Na2O2:
Cr3+ + 3OH− → Cr(OH)3↓;
Cr(OH)3 + OH− → [Cr(OH)4]− → CrO2− + 2H2O;
2CrO2− + 322 + 2OH− → 2CrO42 + 4H2O.
3-4 (), 2-3 22 4 NaOH. 3-4. - CrO42 . ϳ . 6-8 2-3 22. . H2CrO6 (CrO5).
, Cr3+ CrO42 , CrO42 H2CrO6 .
Cr3+ .
Cr3+ KMnO4 Cr2O72:
10Cr3+ + 6MnO4− + 11H2O → 5Cr2O72 + 6Mn2+ + 22+.
- Mn2+ -:
2MnO42 + 3Mn2+ + 7H2O → 5MnO(OH)2↓ + 4H+.
MnO(OH)2 . , Cr2O72.
4-5 (), 3-4 10 KMnO4 (( KMnO4)=0,1/3). . .
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Cr3+ - Cr2O72 :
2Cr3+ + 3S2O82 + 7H2O → Cr2O72 + 6SO42 + 14+.
=1-2 . - .
5-6 (NH4)2S2O8, (( 2SO4)=2,0/3) AgNO3, , 2-3 () () . Cr3+ , - , - Ag+ AgCl. ϳ . Cr2O72.
2-3 22, , CrO5 H2CrO6:
Cr2O72 + 422 + 2+ → 2H2CrO6 + 3H2O.
- CrO5 , Cr3+ CrO42 Cr2O72 .
=2-3. H2CrO6 , , .
CrO5, - 6+.
- ºCrO42/CrO2 0,12 ( ), ºCr2O72/2Cr3+ +1,36 ( ).
, Cr3+ , , , 22 , 0,12. Cr3+ , +1,36 (ºMnO4−/Mn2+ = +1,52; ºS2O82/2SO42 = +2, 01 ).
Cr3+ - :
Cr2O72 + 32 → 2CrO5,
Cr2O72 + 52 → 2CrO62.
, , -:
2CrO42 + 4+ → 2H2CrO4 Cr2O72 + 2+ + 2.
, , 22:
Cr2O72 + 222 → 2CrO5 + 2 +2+
Cr2O72 + 322 →2H2CrO6 + 2;
³ H3CrO8 , 5+:
.
ֳ Cr2O13:
.
(H3CrO8) Cr3+ CrO42 :
Cr3+ + 3− → Cr(OH)3↓;
Cr(OH)3 + OH− → [Cr(OH)4]−;
[Cr(OH)4]− → CrO2− + 2H2O;
CrO2− + 522 + 2OH− → CrO83 + 6H2O;
2CrO42 + 722 + 2OH− → 2CrO83+ 8H2O.
Cr3+ (KMnO4 (NH4)2S2O8) , - , -, , , .
5. Cr3+- CrO42-
- , Cr3+, . Cr3+ - :
4.5.3. Zn2+
1. 䳿 , Zn2+, , :
Zn2+ + 2NH3H2O → Zn(OH)2↓ + 2NH4+;
Zn(OH)2↓ + 4NH3H2O → [Zn(NH3)4](OH)2 + 4H2O;
[Zn(NH3)4](OH)2 .
2. Zn2+ :
2Zn2+ + 232 + H2O → Zn2(OH)23↓ + 2↑.
3. - Zn2+ :
Zn2+ + 2S → ZnS↓ + 2H+;
Zn2+ + S2 → ZnS↓.
3-4 , 2-3 5-7 , . , ZnS . . - .
4. () K4[Fe(CN)6] Zn2+ :
3Zn2+ + 2[Fe(CN)6]4 + 2+ → 2Zn3[Fe(CN)6]2↓.
Zn2+ Al3+.
5. 䳿 , Zn2+, () :
, , Zn2+ .
2-3 Zn2+ , 5 (( NaOH)=2,0/3). , . 2-3 , , ( ). Zn2+ . Zn2+ .
, Zn2+.
6. Zn2+ .
, , () (NH4)2[Hg(SCN)4]. Zn2+ () Zn[Hg(SCN)4]. .
. ()
, . , , (NH4)2[Hg(SCN)4].
Zn2+ Cu2+, Ni2+, Cd2+ , 3+ .
() (NH4)2[Hg(SCN)4] Cu2+ Zn2+ - () () :
2(NH4)2[Hg(SCN)4] + Zn2+ + Cu2+ → u[Hg(SCN)4]Zn[Hg(SCN)4] + 4NH4+.
Zn2+ 2+ - () :
2(NH4)2[Hg(SCN)4] + Zn2+ + C2+ → [Hg(SCN)4]Zn[Hg(SCN)4] + 4NH4+.
- Zn2+ .
7. Zn2+ . . Zn2+ Co(NO3)2, . Zn2+ - , CoZnO2. Al3+, - , Cr3+, Cu2+, Ni2+, .
8. Zn2+ . Zn2+ ( As3+ AsV) , .
4.5.4. Sn2+
2+ 4+.
1. Sn2+ : ºSn2+/Sn4+= +0,2. . Sn2+ Bi3+ Hg2+ .
Bi3+ Hg2+ 䳿 Sn2+ :
Sn2+ + 2− → Sn(OH)2↓;
Sn(OH)2 + 2− → [Sn(OH)4]2;
[Sn(OH)4]2 → SnO22 + 2H2O.
: 2Bi3+ + 3SnO22 + 6− → 2Bi↓ + 3SnO32 + 3H2O.
4 , Sn2+, (( NaOH)=2,0/3) Sn(OH)2, 1-2 , Bi(NO3)2. Sn2+ .
Sb3+, Sn2+ . Bi(NO3)2, , Sn2+ C6H5NH2.
Sn2+ . Sn2+ .
2. Sn2+ Hg2+ :
Hg2+ + SnO22− + 2OH− → Hg↓ + SnO32 + H2O.
.
3. Sn2+ :
Sn2+ + H2S → SnS↓ + 2H+.
- SnS.
4. Sn2+ 6+. 䳿 Sn2+ ( (NH4)2MoO4 ) , , ((NH4)3PO412MoO3) Sn2+ , :
3Sn2+ + MoO42 + 4+ → 3Sn4+ + MoO2↓ + 22;
3Sn2+ + MoO3 + 2+ → 3Sn4+ + MoO2↓ + 2.
Sn2+ -, MoO42 MoO3 Sn2+ - , Sn2+, Sn4+, 6+ , 5+. . .
. . , .
Sn2+ . , . Sn2+ .
Sn2+. Sn2+ , .
5. Co2+, Ni2+, Cu2+, Cr3+, Mn2+, Sb3+ Sn2+ 䳿 Fe3+ .
1-2
1-2 FeCl3 NaHC4H4O6, .
Sn2+ - , , Fe2+ , :
2Fe3+ + Sn2+ → 2Fe2+ + Sn4+
4.5.5. Sn4+
, 3+, Sn4+ . 4+.
SnCl4 Sn(OH)4↓:
SnCl4 + 4HOH → Sn(OH)4 + 4HCl.
Sn(OH)4 , 4+ :
Sn(OH)4 + 6HCl → H2[SnCl6] + 4H2O.
Sn2+:
Mg + [SnCl6]2 → Mg2+ + Sn2+ + 6Cl−;
Fe + [SnCl6]2 → Fe2+ + Sn2+ + 6Cl−.
, 4+, , , 3-4. . Mg2+ Mg(OH)2, Fe2+ Fe(OH)2, Fe(OH)3 . Sn2+ SnO22:
Sn2+ + 2OH− → Sn(OH)2↓;
Sn(OH)2 + 2OH− + [Sn(OH)4]2− → SnO22 + 2H2O.
SnO22 Sn2+ Bi3+ .
4+ 䳺 :
H2[SnCl6] + 2H2S → SnS2↓ + 6HCl;
[SnCl6]2 + 2H2S → SnS2↓ + 4H+ + 6Clˉ
SnS2, .
4.5.6. As3+ As5+
, !
, , , AsO33 AsO43. - As3+:
AsO33 + 6+ → As3+ + 3H2O,
- As5+:
AsO43 + 8+ → As5+ + 4H2O.
1. As3+ As5+ 2S:
2As3+ + 3H2S → As2S3↓ + 6H+,
2As5+ + 5H2S → As2S3↓ + 10H+ + 2S.
As2S3 .
2-33 0,53 70-800. ( ). As3+ As5+ As2S3 - . Sn2+, Sb3+, Bi3+, Cu2+, Hg2+, Cd2+ .
2. 䳿 ( MgCl2 NH3H2O NH4Cl) AsO43 NH4MgAsO4. AsO33 . , , , .
. , , 22 AsO33 AsO43, NH3H2O. Cr(OH)3, Al(OH)3, Sn2+ , NH4Cl Mg(OH)2, MgCl2.
Zn2+ Cr(OH)3, [Zn(NH3)4]Cl2.
AsO43 NH4MgAsO4.
3. AsO43 As5+ - , . :
AsO43 + 2I− + 2H+ → AsO33 + I2 + H2O;
As5+ + 2I− → As3+ + I2.
As3+ AsO33 -, .
Sn2+ Sn4+, Sn2+ -, Sn4+ - . . Fe3+, Fe2+, Sb3+, Cr3+, Cu2+, Ni2+, Co2+. Fe2+ Sb3+ , .
4. Ag+ - - , - :
AsO43 + 3Ag+ → Ag3AsO4↓;
AsO33 + 3Ag+ → Ag3AsO3↓.
. [Ag(NH3)2]+.
Ag+- SnIV. SnO32 Sn(OH)4.
- 䳿 AgNO3 AgCl, .
5. 䳿 - Sn2+ . , Sn2+ AsO43, .
Sn2+ - :
AsO43 + 12(NH4)2MoO4 + 24H+ → (NH4)3AsO412MoO3↓ + 21NH4+ + 12H2O.
, . .