Grupa 3 cationi

Question 1

Al3+ + (NH4)2S

Answer 1

2Al3+ + 3(NH4)2S + 6H2O = 2Al(OH)3↓ + 6NH4+
+ 3H2S↑

Question 2

Al3+ + KOH

Answer 2

Al3+ + 3KOH = Al(OH)3↓ + 3K+ pp alb gelatinos
Al(OH)3 + KOH = KAlO2 + 2H2O sau
Al(OH)3 + KOH= K[Al(OH)4]
Al(OH)3 + 3HCl = AlCl3 + 3H2O

Question 3

Al3+ + alizarina

Answer 3

Cu alizarina formează lacuri de culoare roşie

Question 4

Al3+ + o-oxichinoleina

Answer 4

pH = 5,0 (tampon acetat de
sodiu + acid acetic) formează un complex chelat greu solubil, de culoare
galben-verzuie

Question 5

Cr3+ + (NH4)2S

Answer 5

2Cr3+ + 3(NH4)2S + 6H2O = 2Cr(OH)3↓ + 6NH4
+ 3H2S↑ pp verde cenusiu gelatinos

Question 6

Cr3+ + KOH

Answer 6

Cr3+ + 3KOH = Cr(OH)3↓ + 3K+
Cr(OH)3 + KOH = KCrO2 + 2H2O
Cr(OH)3 + KOH = K[Cr(OH)4]

Question 7

Cr3+ + complexon III

Answer 7

formează cu cromul trivalent puternic hidratat, în mediu slab acid, un
complex violet prin încălzire la fierbere

Question 8

Mn2+ + (NH4)2S

Answer 8

Mn2+ + (NH4)2S = MnS↓ + 2NH4
pp roz
MnS + 2HCl = MnCl2 + H2S↑
devine verde

Question 9

Mn2+ + reacţia Crum-Volhard

Answer 9

2Mn2+ + 5PbO2 + 6HNO3 = 2HMnO4 + 3Pb(NO3)2 + 2Pb2+ + 2H2O
trece in violet

Question 10

Mn2+ + (NH4)2S2O8

Answer 10

2Mn2+ + 5(NH4)2S2O8 + 8H2O = 2HMnO4 + 5(NH4)2SO4 + 5H2SO4 + 4H+ trece in violet

Question 11

Mn2+ + reacţia Denigés

Answer 11

2Mn(OH)2 + 5Br2 + 12KOH = 2KMnO4 + 10KBr + 8H2O

Question 12

Mn2+ + KIO4

Answer 12

2Mn+2 + 5IO4- + 3H2O = 2MnO4- + 5IO3- + 6H+

Question 13

Fe2+ + (NH4)2S

Answer 13

Fe2+ + (NH4)2S = FeS↓ + 2NH4

Question 14

Fe2+ + K4[Fe(CN)6]

Answer 14

Fe2+ + K4[Fe(CN)6] = FeK2[Fe(CN)6]↓ + 2K+
sau
2Fe2+ + K4[Fe(CN)6] = Fe2[Fe(CN)6]↓ + 4K+
pp alb
3Fe2[Fe(CN)6] + 3/2O2 + 3H2O = Fe4[Fe(CN)6]3↓ + 2Fe(OH)3↓

Question 15

Fe2+ + K3[Fe(CN)6]

Answer 15

4Fe2+ + 3K3[Fe(CN)6] = Fe3[Fe(CN)6]2↓ + FeK[Fe(CN)6]↓ + 8K+
pp albastru inchis- albastrul lui Turnbull

Question 16

Fe2+ + o-fenantrolina

Answer 16

in sol usor acida -> complex chelat rosu

Question 17

Fe2+ +2, 2’-dipiridil

Answer 17

-> complex rosu

Question 18

Fe2+ + KMnO4

Answer 18

5Fe2+ + KMnO4 + 4H2SO4 = 5Fe3+ + MnSO4 + 3SO4 2- + K+ + 4H2O

Question 19

Fe3+ + (NH4)2S

Answer 19

2Fe3+ + 3(NH4)2S = Fe2S3↓+ 6NH4+ pp negru

Question 20

Fe3+ + KSCN

Answer 20

Fe3+ + 3KSCN = Fe(SCN)3 + 3K+
pp rosu sange

Question 21

Fe3+ + K4[Fe(CN)6]

Answer 21

4Fe3+ + 3K4[Fe(CN)6] = Fe4[Fe(CN)6]3↓ + 12K+
albastru de Berlin

Question 22

Fe3+ + CH3COONa

Answer 22

3Fe3+ + 6CH3COONa + 2H2O= [Fe3(CH3COO)6(OH)2]+ + 6Na+ + 2H+
complex brun roscat
[Fe3(CH3COO)6(OH)2]+ + 4H2O = 3CH3COOFe(OH)2 + 3CH3COOH + H+

Question 23

Fe3+ + acid salicilic

Answer 23

pH=1 -> violet
pH=4 -> rosu portocaliu

Question 24

Fe3+ + o-fenantrolina

Answer 24

-> complex albastru

Question 25

Fe3+ + KI

Answer 25

2Fe3+ + 2KI = 2Fe2+ + I2 + 2K+

Question 26

Co2+ + (NH4)2S

Answer 26

Co2+ + (NH4)2S = CoS↓ + 2NH4+ pp negru
3CoS + 8HNO3 = 3Co(NO3)2 + 3S↓ + 2NO↑ + 4H2O
3CoS + 2(3HCl + HNO3) = 3CoCl2 + 3S↓ + 2NO↑ + 4H2O

Question 27

Co2+ +KOH

Answer 27

CoCl2 + KOH = Cl-Co-OH↓ + KCl pp albastru
Cl-Co-OH + KOH = Co(OH)2↓ + KCl pp roz

Question 28

Co2+ + NH4OH

Answer 28

Co2+ + 2NH4OH = Co(OH)2↓ + 2NH4+
Co(OH)2 + 2NH4Cl + 4NH4OH = [Co(NH3)6]Cl2 + 6H2O galben murdar

Question 29

Co2+ + KSCN

Answer 29

Co2+ + 4NH4SCN = (NH4)2[Co(SCN)4] + 2NH4+
coloratie albastra

Question 30

Co2+ +(NH4)2[Hg(SCN)4]

Answer 30

Co2+ + (NH4)2Hg(SCN)4 + Zn2+ = Co[Hg(SCN)4].Zn[Hg(SCN)4]↓ + 4NH4+
pp albastru cristalin

Question 31

Co2+ + piridina

Answer 31

Co2+ + 2KSCN + 4Py = CoPy4(SCN)2↓ + 2K+ pp roz

Question 32

Ni2+ + (NH4)2S

Answer 32

Ni2+ + (NH4)2S = NiS↓ + 2NH4+ pp negru
a. 3NiS + 8HNO3 = 3Ni(NO3)2 + 3S↓ + 2NO↑ + 4H2O
b. 3NiS + 6HCl + 2HNO3 = 3NiCl2 + 3S↓ + 2NO↑+ 4H2O

Question 33

Ni2+ + NH4OH

Answer 33

Ni2+ + NH4OH = NiOH+ + NH4
NiOH+ + 7NH4OH = Ni(NH3)62↓ + NH4+ + 6H2 col albastra

Question 34

Ni2+ + piridina

Answer 34

Ni2+ + 2KSCN + 4Py = NiPy4(SCN)2↓ + 2K+
pp albastru ceruleu

Question 35

Ni2+ + dimetilglioxima

Answer 35

m amoniacal -> pp rosu matasos

Question 36

Ni2+ + o-oxichinoleina

Answer 36

pH=6-9.5 la cald -> complex galben

Question 37

Zn2+ + (NH4)2S

Answer 37

Zn2+ + (NH4)2S = ZnS↓ + 2NH4+ pp alb

Question 38

Zn2+ + NH4OH

Answer 38

Zn2+ + 2NH4OH = Zn(OH)2↓ + 2 NH4+ pp alb
Zn(OH)2 + 4NH4OH = Zn(NH3)4(OH)2 + 4H2O

Question 39

Zn2+ + K4[Fe(CN)6]

Answer 39

Zn2+ + K4[Fe(CN)6] = K2Zn[Fe(CN)6]↓ + 2K+
pp alb cristalin

Question 40

Zn2+ + (NH4)2[Hg(SCN)4]

Answer 40

Zn2+ + 2(NH4)2[Hg(SCN)4] + Cu2+ = Zn[Hg(SCN)4].Cu[Hg(SCN)4]↓+ 4NH4+ pp violet

Question 41

Zn2+ + piridina

Answer 41

Zn2+ + 2KSCN + 2Py = ZnPy2(SCN)2↓ + 2K+
pp alb cristalin

Question 42

Zn2+ + ditizona

Answer 42

rosu purpuriu

Question 43

subgrupa aluminiului+ reactiv de grupa

Answer 43

2Al3+ + 3(NH4)2S + 6H2O = 2Al(OH)3↓ + 6NH4+
+ 3H2S↑
2Cr3+ + 3(NH4)2S + 6H2O = 2Cr(OH)3↓ + 6NH4
+ 3H2S↑ pp verde cenusiu gelatinos

Question 44

subgrupa manganului+ reactiv de grupa

Answer 44

Mn2+ + (NH4)2S = MnS↓ + 2NH4
pp roz
MnS + 2HCl = MnCl2 + H2S↑
devine verde
Fe2+ + (NH4)2S = FeS↓ + 2NH4
2Fe3+ + 3(NH4)2S = Fe2S3↓+ 6NH4+ pp negru
Co2+ + (NH4)2S = CoS↓ + 2NH4+ pp negru
3CoS + 8HNO3 = 3Co(NO3)2 + 3S↓ + 2NO↑ + 4H2O
3CoS + 2(3HCl + HNO3) = 3CoCl2 + 3S↓ + 2NO↑ + 4H2O
Ni2+ + (NH4)2S = NiS↓ + 2NH4+ pp negru
a. 3NiS + 8HNO3 = 3Ni(NO3)2 + 3S↓ + 2NO↑ + 4H2O
b. 3NiS + 6HCl + 2HNO3 = 3NiCl2 + 3S↓ + 2NO↑+ 4H2O
Zn2+ + (NH4)2S = ZnS↓ + 2NH4+ pp alb

Question 45

cationi grupa 3 + piridina

Answer 45

Co2+ + 2KSCN + 4Py = CoPy4(SCN)2↓ + 2K+ pp roz
Ni2+ + 2KSCN + 4Py = NiPy4(SCN)2↓ + 2K+
pp albastru ceruleu
Zn2+ + 2KSCN + 2Py = ZnPy2(SCN)2↓ + 2K+
pp alb cristalin