quimica

32 Prof. Marco Antonio Alves da Silva

7. Classificação de cátions
7.1. Esquema geral de separação de cátions
Ag +, Hg 2+2, Pb +2, Hg +2, Bi+3, Cu+2, Cd +2, As +3, As +5, Sb +3, Sb +5, Sn+2, Sn+4, Fe +3,
Al+3, Cr+3, Ni+2, Co +2, Zn+2, Mn+2, Ca+2, Sr+2, Ba+2, Mg +2, Na+, K+ e NH4+
AgCl, Hg 2Cl2,
HCl 6M
PbCl2
GRUPO I
Hg +2, Bi+3, Cu+2, Cd +2, As +3, As +5, Sb +3, Sb +5, Sn+2, Sn+4, Fe +3,Al+3,
Cr+3, Ni+2, Co +2, Zn+2, Mn+2, Ca+2, Sr+2, Ba+2, Mg +2, Na+, K+ e NH4+
HCl 12M + HNO3 16M
HgS, Bi2S3, CuS, CdS,
HCl 6M (até pH 0,5)
As 2S5, Sb 2S5, SnS2
CH3CSNH2 1M
GRUPO II
Fe +3,Al+3, Cr+3, Ni+2, Co +2, Zn+2, Mn+2,
Ca+2, Sr+2, Ba+2, Mg +2, Na+, K+ e NH4+
NaOH 4M
Al(OH)3, Fe(OH)3,
H2O2 3%
Cr(OH)3
∆
GRUPO IIIa
Ni+2, Co +2, Zn+2, Mn+2, Ca+2, Sr+2,
Ba+2, Mg +2, Na+, K+ e NH4+
NiS, CoS,
MnS, ZnS
GRUPO IIIb

(NH4)2S 0,2M
∆
Ca+2, Sr+2, Ba+2, Mg +2,
Na+, K+ e NH4+

CaCO3, SrCO3,
BaCO3
GRUPO IV

HCl 6M + NH4OH 6M
(NH4)2CO3 1,5M
Mg +2, Na+,
K+ e NH4+
GRUPO V

Química Analítica Qualitativa 33

7.2. Marcha sistemática
7.2.1.

Grupo I
Ag+, Hg2+2, Pb+2
HCl 6M
AgCl, Hg2Cl2, PbCl2
H2O ∆

AgCl, Hg2Cl2
NH4OH 6M

Pb+2
CH3COOH 6M
K 2CrO 4 1M
PbCrO 4

Ag(NH3)2+
HNO 3 6M

Hg0 + HgNH2Cl

AgCl

7.2.2.

Grupo II
As +3, As +5, Sb+3, Sb +5, Sn+2, Sn+4

Pb+2, Hg +2, Bi+3, Cu+2, Cd+2,
As +3, As +5, Sb+3, Sb +5, Sn+2, Sn+4

HCl 12M + HNO 3 16M
As +5, Sb+5, Sn+4

HCl 12M + HNO 3 16M

CH3CSNH2 1M

Pb+2, Hg +2, Bi+3, Cu+2, Cd+2,
As +5, Sb +5, Sn+4

As 2S 5, Sb2S5, SnS 2

HCl 6M até pH 0,5
CH3CSNH2 1M

HCl 12M

HgS, PbS, Bi2S 3, CuS, CdS,
As 2S5, Sb 2S 5, SnS2
NaOH 3M

As 2S 5, S
HNO 3 6M
H2O

HgS, PbS, Bi2S 3,
CuS, CdS

AsS4-3, SbS 4-3, SnS 3-2
-3

-3

-2

AsO4 , SbO 4 , SnO 3
HCl 6M
As 2S 5, Sb2S5, SnS 2

Sb+3, Sn+4
Fe 0
Sb0

H3AsO4
NaOAc 0,2M
AgNO3 0,2M
Ag3AsO 4

Sn+2
HgCl2
Hg2Cl2, Hg0

34 Prof. Marco Antonio Alves da Silva

Pb+2, Hg +2, Bi+3, Cu+2, Cd+2
HCl 6M (até pH