Saturday, January 12, 2013

Lab 7 - 9 Qualitative Analysis Data Sheet


 In order to make the qualitative analysis table fit on this blog, I had to post it in "paint" and make it a picture.
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Procedure #
Liquid or Solid Used
Reagent
Observation
Ppt contains
Centrifugate Contains
Applicable Equations
1
Group I, II, III, IV
HCl
White & Yellow
AgCl, Hg2Cl2,   PbCl2
Group 2, 3, and 4
Ag+ + HCl  à AgCl + H+
2Hg+ + 2HCl 
à Hg2Cl2 + 2H+
Pb2+ + 2HCl 
à PbCl2 + 2H+
2
PPT From #1
Hot H2O
PPT Still Present
AgCl, HgCl2
Pb2+
PbCl­2 + HO + Heat à Pb2+ (aq) + Cl-(aq)
3
Half of decant from #2
K2CrO2
Yellow Precipitate
PbCrO4
N/A
Pb2+ (aq) + K2CrO4 à PbCrO4 + 2K+
Other half of decant
H2SO4
White Precipitate
PbSO4
N/A
H2SO4 + Pb2+ à PbSO4 + 2H+
4a
PPT From #2
NH3
Black/Gray PPT
Hg + HgNH2Cl
Ag(NH)2+
AgCl + 2 NH3 à Ag(NH)2+ + Cl-
Hg2Cl2 + NH
à Hg(l) + HgNH2Cl(s) + NH4+ + Cl-
4b
Decantate
HNO3
White Precipitate
AgCl
N/A
Ag(NH3)2+(aq) + 2H+(aq) →  Ag+(aq) + 2 NH4+(aq)
Ag+(aq) + Cl-(aq)   AgCl(s)
5
Decant from #1
H2O2, (NH4)2S, NH4C2H3, H2O, Heat
Dark/Hunter Green
PbS, Bi2S3, CuS, CdS
Group III and IV
Pb2+ + S2- à PbS
2Bi3+ + 3S2- 
à Bi2S3
Cu2+ + S2- 
à CuS
Cd2+ + S2- 
à CdS
6a
PPT From #5
HNO3, H2SO4, Heat
Yellow Crystal Forms, ions   dissolve, and White Smoke Appears
Sulfur
Group II ions
PbS + 2 NO3- +4H+ à Pb2+ + S +2NO2 + 2H2O
CuS + 2 NO3- +4H+ 
à Cu2+ + S +2NO2 + 2H2O
CdS + 2 NO3- +4H+ 
à Cd2+ + S +2NO2 + 2H2O
Bi2S3 + 6 NO3- +12H+ 
à 2Bi2+ + 3S +6NO2 + 6H2O
6b
Decant from 6a
Ice, NH4, HC2H3O2, KCr2O4
White Precipitate,
Then Dissolve, Then Yellow PPT
PbSO4
Bi3+, Cu2+, Cd2+
Pb2+ + SO42- + ICE à PbSO+ Heat
PbSO4 + 3NH4 + C2H3O2 
à Pb(C2H3O2­­­)3- + NH4 + SO42-
Pb(C2H3O2­­­)3+ KCrO4 
à PbCrO4 + 3(C2H3O2)- + K+
7a
Decant from #6
NH3
Blue
Bi(OH)3(s)
Cu(NH3)42+,   Cd(NH3)42+
Bi3 + 3NH3 +3H2à Bi(OH)3 +3NH4+
Cu2+ + 4NH3 
à Cu(NH3)42+ (blue)
Cd2+ + 4NH3 
à Cd(NH3)42+
NaOH, SnCl2
7b
PPT From #7a
H2O, NaOH, SnCl2
Jet Black
Bi(S)
N/A
SnCl+3NaOH à Sn(OH)3- +3Na+ +2Cl-
BiOH + SnOH 
à SN(OH)62- + Bi0(S)
8
5drops Decant from #7
HC2H3O2
Lost Color
N/A
Cu2Fe(CN)6
Cu(NH3)42+ + 4HCH3CO2­ à Cu2++ 4NH4 + 4CH3CO­2
2Cu2+ + K4Fe(CN)6 
à CuFe(CN)6 4K-
K4Fe(CN)6
Turned Red
9
Decant from #7
KCN, (NH4)2S
Yellow
CdS
N/A
Cd(NH3)42+ + 4CN- àCd(CN)42-+4(NH3)
Cd(CN)42- 
ßà Cd2+ + 4CN-
Cd2+ + S2- 
à CdS
10a
Decant from #5
NH4Cl
NH3
Blackish
NiS (Black)
FeS (Black)
CoS (Brown)
MnS (Pink)

Group IV
Fe2+ + S2- à FeS
Co2+ + S2- 
à CoS
Ni2+ + S2- 
à NiS
Mn2+ + S2- 
à MnS
10b
Precipitate
 from 10a
(NH4)2S Heat NH4C2H3O2
NiS
11
PPT from #10
HCl, Heat, HNO3 H2O,


 NaOH H2O2
PPT Dissolves Sulfur PPT
Sulfur
N/A
Fe3+ + 3(OH)- à Fe(OH)3 (red)
Ni2+ + 2(OH)- 
à Ni(OH)(Green)
Mn2+ + 2(OH)- 
à Mn(OH)(part 1)
Mn(OH)2 + 2(OH)- à MnO2 +2(H2O)  (Part 2)
MnO2 + H2O2  
à MnO +H2O + O2  (Blackish brown)
2Co(OH)+ H2O2 
à 2Co(OH)2 + 2H2O + O2 (pink to blue)
(Note: the mechanism for Co and Mn are similar –
I abbreviated the Co formula here)
Darkened
Fe(OH)3
Ni(OH)2
MnO
Co(OH)2
12
¼ of PPT from #11
KSCN
Red
Fe(SCN)63-
Fe3+ + 6SCN- à Fe(SCN)63-
13
¼ of PPT from #11
NaF
NaSCN
Blue hue
Co(SCN)43+
Co2+ + 4(SCN)- à Co(SCN)42-
14
¼ of PPT from #11
NH3DMG (dimethylgloxime)
Strawberry Red
NiC8H4N4O4
Ni2+ + 6NH3 à Ni(NH3)62+
Ni(NH3)62+ + 2(CH3)2C2(NOH)2 à NiC8H4N4O+ 2NH4++4NH3
15
¼ of PPT from #11
H2O
HNO3
NaBiO3
Purple (pink to reddish purple)
MnO4-
2Mn2+ + 5HBiO3 + 9H+ à 2MnO4 + 5Bi3+ + 7H2O







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