Qualitative Analysis. István Szalai. Institute of Chemistry, Eötvös University

Transcription

1 Institute of Chemistry, Eötvös University 2016

2 Cations (Group I-III) The cations of Group I can be precipitated as sulfides from acidic solution (ph 2) by H 2 S; the precipitates are insoluble in (NH 4 ) 2 S and KOH. The cations of Group II can be precipitated in acidic media with H 2 S but the sulfides of are soluble in (NH 4 ) 2 S x and KOH with formation of thiocomplexes. The cations of Group III can be precipitated with (NH 4 ) 2 S in neutral or slightly alkaline solutions, but cannot be precipitated with H 2 S in acidic solutions.

3 Cations (Group I-III) Hydrolysis (ph=5): Bi(OH) 3, Sb(OH) 3, SbO(OH) 3, Sn(OH) 2, Sn(OH) 4, Al(OH) 3, Cr(OH) 3, Fe(OH) 3

4 Cations (Group I-III) Hydrolysis (ph=5): Bi(OH) 3, Sb(OH) 3, SbO(OH) 3, Sn(OH) 2, Sn(OH) 4, Al(OH) 3, Cr(OH) 3, Fe(OH) 3 HCl: AgCl, Hg 2 Cl 2, PbCl 2

5 Cations (Group I-III) NaOH (2M): White precipitates: Bi(OH) 3, Pb(OH) 2, Cd(OH) 2, Sn(OH) 2, Sn(OH) 4, Sb(OH) 3, SbO(OH) 3, Al(OH) 3, Zn(OH) 2

6 Cations (Group I-III) NaOH (2M): White precipitates: Bi(OH) 3, Pb(OH) 2, Cd(OH) 2, Sn(OH) 2, Sn(OH) 4, Sb(OH) 3, SbO(OH) 3, Al(OH) 3, Zn(OH) 2 Soluble in excess of NaOH: Pb(OH) 2 4, Sn(OH)2 4, Sn(OH)2 6, Sb(OH) 4, Sb(OH) 6, Zn(OH) 2 4, Al(OH) 4

7 Cations (Group I-III) NaOH (2M): Colored precipitates: Ag 2 O, HgO, Cu(OH) 2, Ni(OH) 2, Co(OH) 2, Mn(OH) 2, Fe(OH) 2, Fe(OH) 3, Cr(OH) 3

8 Cations (Group I-III) NaOH (2M): Colored precipitates: Ag 2 O, HgO, Cu(OH) 2, Ni(OH) 2, Co(OH) 2, Mn(OH) 2, Fe(OH) 2, Fe(OH) 3, Cr(OH) 3 Soluble in excess: Cr(OH) 4

9 Cations (Group I-III) NaOH (2M): Colored precipitates: Ag 2 O, HgO, Cu(OH) 2, Ni(OH) 2, Co(OH) 2, Mn(OH) 2, Fe(OH) 2, Fe(OH) 3, Cr(OH) 3 Soluble in excess: Cr(OH) 4 Can be reduced by H 2 O 2 in basic solution: Ag 2 O, HgO Can be oxidized by H 2 O 2 in basic solution: Co(OH) 2, Cr(OH) 3, Mn(OH) 2, Fe(OH) 2

10 Cations (Group I-III) NH 3 (2M): The first reaction is the same like with NaOH (except Hg(I) and Hg(II)).

11 Cations (Group I-III) NH 3 (2M): The first reaction is the same like with NaOH (except Hg(I) and Hg(II)). Complex formation in excess of NH 3 : Ag(NH 3 ) + 2, Cd(NH 3) 2+ 4, Zn(NH 3) 2+ 4, Cu(NH 3) 2+ 4, Ni(NH 3) 2+ 6, Co(NH 3 ) 2+ 6

12 Cations (Group I-III) H 2 S (ph=2): Black or brown precipitates: Bi 2 S 3, PbS, HgS, CuS, Ag 2 S, SnS

13 Cations (Group I-III) H 2 S (ph=2): Black or brown precipitates: Bi 2 S 3, PbS, HgS, CuS, Ag 2 S, SnS Yellow or orange precipitates: Sb 2 S 3, CdS, SnS 2, As 2 S 3

14 Cations (Group I-III) H 2 S (ph=2): Black or brown precipitates: Bi 2 S 3, PbS, HgS, CuS, Ag 2 S, SnS Yellow or orange precipitates: Sb 2 S 3, CdS, SnS 2, As 2 S 3 White precipitates (in buffered or basic solution): ZnS Redox reaction: Fe 3+, As(V), Sb(V)

15 Cations (Group I-III) (NH 4 ) 2 S: Black or brown precipitates: Bi 2 S 3, PbS, HgS, CuS, Ag 2 S, NiS, CoS, FeS, Fe(OH) 3

16 Cations (Group I-III) (NH 4 ) 2 S: Black or brown precipitates: Bi 2 S 3, PbS, HgS, CuS, Ag 2 S, NiS, CoS, FeS, Fe(OH) 3 Other precipitates: ZnS, CdS, MnS, Cr(OH) 3, Al(OH) 3

17 Cations (Group I-III) (NH 4 ) 2 S: Black or brown precipitates: Bi 2 S 3, PbS, HgS, CuS, Ag 2 S, NiS, CoS, FeS, Fe(OH) 3 Other precipitates: ZnS, CdS, MnS, Cr(OH) 3, Al(OH) 3 Thiocomplexes: AsS 3 3, AsS3 4, SbS3 3, SbS3 4, SnS3 3

18 Cations (Group I-III) KI: Colored precipitates: BiI 3, Hg 2 I 2, HgI 2, PbI 2, AgI, CuI

19 Cations (Group I-III) KI: Colored precipitates: BiI 3, Hg 2 I 2, HgI 2, PbI 2, AgI, CuI Complexes: BiI 4, HgI2 4, CdI2 4, (PbI2 4 ), (AgI 2 ), (CuI 2 )

20 Cations (Group I-III) KI: Colored precipitates: BiI 3, Hg 2 I 2, HgI 2, PbI 2, AgI, CuI Complexes: BiI 4, HgI2 4, CdI2 4, (PbI2 4 ), (AgI 2 ), (CuI 2 )

21 Cations (Group I-III) KI: Colored precipitates: BiI 3, Hg 2 I 2, HgI 2, PbI 2, AgI, CuI Complexes: BiI 4, HgI2 4, CdI2 4, (PbI2 4 ), (AgI 2 ), (CuI 2 ) Redox reaction: Cu 2+, Fe 3+, As(V), Sb(V)

22 Cations (Group I-III) KI: Colored precipitates: BiI 3, Hg 2 I 2, HgI 2, PbI 2, AgI, CuI Complexes: BiI 4, HgI2 4, CdI2 4, (PbI2 4 ), (AgI 2 ), (CuI 2 ) Redox reaction: Cu 2+, Fe 3+, As(V), Sb(V) I 2 (I 3 ): In acidic solution: Sn(II) After adding NaHCO 3 : AsO 3 3

23 Cations (Group I-III) KMnO 4 (slightly acidic solution): Sn(II), Fe(II), Hg 2+ 2, Sb(III), As(III)

24 Cations (Group I-III) KMnO 4 (slightly acidic solution): Sn(II), Fe(II), Hg 2+ 2, Sb(III), As(III) Zn: Acidic solution: Ag +, Cu 2+, Hg 2+ 2, Hg2+, Bi 3+, As(III), As(V), Sb(III), Sb(V), Sn(II), Sn(IV), (Cd 2+ ), (Pb 2+ ), (Ni 2+ ), (Co 2+ ) Fe(III) Fe(II)

25 Date: March 17th 2016, 12:15-13:45 Tools: pen, calculator (non programmable) The use of mobilephone (iphone) is forbidden!

26 Solubility of sulfides in acidic solutions Zn 2+ + S 2 ZnS S 2 + H + HS HS + H + H 2 S Does the ZnS precipitate form in a solution which is 0.1M for aceteic acid and 0.01M for Zn 2+ ions and saturated with H 2 S? K a (CH 3 COOH) = , K a1 (H 2 S) = K a2 (H 2 S) = , K sp =

27 Solubility of sulfides in acidic solutions Zn 2+ + S 2 ZnS S 2 + H + HS HS + H + H 2 S [H + ] = [CH 3 COOH]K a = = M

28 Solubility of sulfides in acidic solutions Zn 2+ + S 2 ZnS S 2 + H + HS HS + H + H 2 S [H + ] = [CH 3 COOH]K a = = M α H = ( ( ) 2 ) =

29 Solubility of sulfides in acidic solutions Zn 2+ + S 2 ZnS S 2 + H + HS HS + H + H 2 S [H + ] = [CH 3 COOH]K a = = M α H = ( ( ) 2 ) = [S 2 ] = [S 2 ] t α H = 0.1 =

30 Solubility of sulfides in acidic solutions [S 2 ] = [S 2 ] t α H = Zn 2+ + S 2 ZnS S 2 + H + HS HS + H + H 2 S 0.1 =

31 Solubility of sulfides in acidic solutions [S 2 ] = [S 2 ] t α H = Zn 2+ + S 2 ZnS S 2 + H + HS HS + H + H 2 S 0.1 = Q = [Zn 2+ ][S 2 ] = =

32 Solubility of sulfides in acidic solutions [S 2 ] = [S 2 ] t α H = Zn 2+ + S 2 ZnS S 2 + H + HS HS + H + H 2 S 0.1 = Q = [Zn 2+ ][S 2 ] = = Q = > K sp = The precipitation of ZnS occurs at this conditions.

33 Which of the following ions give precipitate with ammonium-sulfide in neutral solution? AsO 3 3 I Cr 3+ Cu 2+ Hg 2+ Write the reactions: Al 3+ SnCl 2 4 Ag + Cd 2+ SbCl 4

34 Which of the following ions give precipitate with ammonium-sulfide in neutral solution? AsO 3 3 I Cr 3+ Cu 2+ Hg 2+ Write the reactions: Al 3+ SnCl 2 4 Ag + Cd 2+ SbCl 4

35 Which of the following ions give precipitate with ammonium-sulfide in neutral solution? AsO Al 3+ I Cr 3+ Cu 2+ SnCl 2 4 Ag + Cd 2+ Hg 2+ Write the reactions: SbCl 4

36 Which of the following ions give precipitate with ammonium-sulfide in neutral solution? AsO Al 3+ I + SnCl 2 4 Cr 3+ Cu 2+ Ag + Cd 2+ Hg 2+ Write the reactions: SbCl 4

37 Which of the following ions give precipitate with ammonium-sulfide in neutral solution? AsO Al 3+ I + SnCl 2 4 Cr 3+ + Ag + Cu 2+ Cd 2+ Hg 2+ Write the reactions: SbCl 4

38 Which of the following ions give precipitate with ammonium-sulfide in neutral solution? AsO Al 3+ I + SnCl 2 4 Cr 3+ + Ag + Cu 2+ + Cd 2+ Hg 2+ Write the reactions: SbCl 4

39 Which of the following ions give precipitate with ammonium-sulfide in neutral solution? AsO Al 3+ I + SnCl 2 4 Cr 3+ + Ag + Cu 2+ + Cd 2+ Hg 2+ + Write the reactions: SbCl 4

40 Which of the following ions give precipitate with ammonium-sulfide in neutral solution? AsO Al 3+ I + SnCl 2 4 Cr 3+ + Ag + Cu 2+ + Cd 2+ Hg 2+ + Write the reactions: SbCl 4

41 Which of the following ions give precipitate with ammonium-sulfide in neutral solution? AsO Al 3+ + I + SnCl 2 4 Cr 3+ + Ag + Cu 2+ + Cd 2+ Hg 2+ + Write the reactions: SbCl 4

42 Which of the following ions give precipitate with ammonium-sulfide in neutral solution? AsO Al 3+ + I + SnCl Cr 3+ + Ag + Cu 2+ + Cd 2+ Hg 2+ + Write the reactions: SbCl 4

43 Which of the following ions give precipitate with ammonium-sulfide in neutral solution? AsO Al 3+ + I + SnCl Cr 3+ + Ag + + Cu 2+ + Cd 2+ Hg 2+ + Write the reactions: SbCl 4

44 Which of the following ions give precipitate with ammonium-sulfide in neutral solution? AsO Al 3+ + I + SnCl Cr 3+ + Ag + + Cu 2+ + Cd 2+ + Hg 2+ + Write the reactions: SbCl 4

45 Which of the following ions give precipitate with ammonium-sulfide in neutral solution? AsO Al 3+ + I + SnCl Cr 3+ + Ag + + Cu 2+ + Cd 2+ + Hg 2+ + SbCl 4 + Write the reactions:

46 Which of the following can not be dissolved in water, but can be dissolved in sodium-hidroxide? Cd(OH) 2 Al(OH) 3 Cr 2 (SO 4 ) 3 PbSO 4 Ni(OH) 2 PbS As 2 O 3 Sb 2 S 3 ZnSO 4 AgCl Write the reactions:

47 Which of the following can not be dissolved in water, but can be dissolved in sodium-hidroxide? Cd(OH) 2 + PbS Al(OH) 3 Cr 2 (SO 4 ) 3 PbSO 4 Ni(OH) 2 As 2 O 3 Sb 2 S 3 ZnSO 4 AgCl Write the reactions:

48 Which of the following can not be dissolved in water, but can be dissolved in sodium-hidroxide? Cd(OH) 2 + PbS Al(OH) 3 + As 2 O 3 Cr 2 (SO 4 ) 3 PbSO 4 Ni(OH) 2 Sb 2 S 3 ZnSO 4 AgCl Write the reactions:

49 Which of the following can not be dissolved in water, but can be dissolved in sodium-hidroxide? Cd(OH) 2 + PbS Al(OH) 3 + As 2 O 3 Cr 2 (SO 4 ) 3 + Sb 2 S 3 PbSO 4 Ni(OH) 2 ZnSO 4 AgCl Write the reactions:

50 Which of the following can not be dissolved in water, but can be dissolved in sodium-hidroxide? Cd(OH) 2 + PbS Al(OH) 3 + As 2 O 3 Cr 2 (SO 4 ) 3 + Sb 2 S 3 PbSO 4 Ni(OH) 2 ZnSO 4 AgCl Write the reactions:

51 Which of the following can not be dissolved in water, but can be dissolved in sodium-hidroxide? Cd(OH) 2 + PbS Al(OH) 3 + As 2 O 3 Cr 2 (SO 4 ) 3 + Sb 2 S 3 PbSO 4 + ZnSO 4 Ni(OH) 2 AgCl Write the reactions:

52 Which of the following can not be dissolved in water, but can be dissolved in sodium-hidroxide? Cd(OH) 2 + PbS Al(OH) 3 + As 2 O 3 Cr 2 (SO 4 ) 3 + Sb 2 S 3 PbSO 4 + ZnSO 4 Ni(OH) 2 + AgCl Write the reactions:

53 Which of the following can not be dissolved in water, but can be dissolved in sodium-hidroxide? Cd(OH) 2 + PbS + Al(OH) 3 + As 2 O 3 Cr 2 (SO 4 ) 3 + Sb 2 S 3 PbSO 4 + ZnSO 4 Ni(OH) 2 + AgCl Write the reactions:

54 Which of the following can not be dissolved in water, but can be dissolved in sodium-hidroxide? Cd(OH) 2 + PbS + Al(OH) 3 + As 2 O 3 + Cr 2 (SO 4 ) 3 + Sb 2 S 3 PbSO 4 + ZnSO 4 Ni(OH) 2 + AgCl Write the reactions:

55 Which of the following can not be dissolved in water, but can be dissolved in sodium-hidroxide? Cd(OH) 2 + PbS + Al(OH) 3 + As 2 O 3 + Cr 2 (SO 4 ) 3 + Sb 2 S 3 + PbSO 4 + ZnSO 4 Ni(OH) 2 + AgCl Write the reactions:

56 Which of the following can not be dissolved in water, but can be dissolved in sodium-hidroxide? Cd(OH) 2 + PbS + Al(OH) 3 + As 2 O 3 + Cr 2 (SO 4 ) 3 + Sb 2 S 3 + PbSO 4 + ZnSO 4 Ni(OH) 2 + AgCl Write the reactions:

57 Which of the following can not be dissolved in water, but can be dissolved in sodium-hidroxide? Cd(OH) 2 + PbS + Al(OH) 3 + As 2 O 3 + Cr 2 (SO 4 ) 3 + Sb 2 S 3 + PbSO 4 + ZnSO 4 + Ni(OH) 2 + AgCl Write the reactions:

58 Which of the following can not be dissolved in water, but can be dissolved in sodium-hidroxide? Cd(OH) 2 + PbS + Al(OH) 3 + As 2 O 3 + Cr 2 (SO 4 ) 3 + Sb 2 S 3 + PbSO 4 + ZnSO 4 + Ni(OH) 2 + AgCl + Write the reactions:

59 What single reagent could be used to distinguish between members of the following pairs? CdS, SnS 2 Pb(OH) 2 4, Sn(OH)2 4 Sn(Cl) 2 4, Sb(Cl) 4 Cu(NH 3 ) 2+ 4, Ni(NH 3) 2+ 6

60 What single reagent could be used to distinguish between members of the following pairs? CdS, SnS 2 NaOH Pb(OH) 2 4, Sn(OH)2 4 Sn(Cl) 2 4, Sb(Cl) 4 Cu(NH 3 ) 2+ 4, Ni(NH 3) 2+ 6

61 What single reagent could be used to distinguish between members of the following pairs? CdS, SnS 2 NaOH Pb(OH) 2 4, Sn(OH)2 4 Bi(OH) 3 Sn(Cl) 2 4, Sb(Cl) 4 Cu(NH 3 ) 2+ 4, Ni(NH 3) 2+ 6

62 What single reagent could be used to distinguish between members of the following pairs? CdS, SnS 2 NaOH Pb(OH) 2 4, Sn(OH)2 4 Bi(OH) 3 Sn(Cl) 2 4, Sb(Cl) 4 Hg 2+ Cu(NH 3 ) 2+ 4, Ni(NH 3) 2+ 6

63 What single reagent could be used to distinguish between members of the following pairs? CdS, SnS 2 NaOH Pb(OH) 2 4, Sn(OH)2 4 Bi(OH) 3 Sn(Cl) 2 4, Sb(Cl) 4 Hg 2+ Cu(NH 3 ) 2+ 4, Ni(NH 3) 2+ 6 Fe

64 How can you identify Cd 2+ Cu 2+ in presence of Zn 2+ Pb 2+ in presence of Ca 2+ Ba 2+ in presence of

65 How can you identify Cd 2+ Cu 2+ in presence of NH 3, KCN,H 2 S Zn 2+ Pb 2+ in presence of Ca 2+ Ba 2+ in presence of

66 How can you identify Cd 2+ Cu 2+ in presence of NH 3, KCN,H 2 S Zn 2+ Pb 2+ in presence of NH 3, (NH 4 ) 2 S Ca 2+ Ba 2+ in presence of

67 How can you identify Cd 2+ Cu 2+ in presence of NH 3, KCN,H 2 S Zn 2+ Pb 2+ in presence of NH 3, (NH 4 ) 2 S Ca 2+ Ba 2+ in presence of (NH 4 ) 2 (COO) 2

68 How can you identify Co(II), Cu(II) and Fe(III) ions in presence of each other?

69 How can you identify Co(II), Cu(II) and Fe(III) ions in presence of each other? Fe NH 4 SCN, NaF

70 Which of the substance can be identified by following the next description? 1. White crystalline compound, that dissolves in water. The solution is colorless and acidic. 2. White precipitate forms with ammonia, which can not be dissolved in excess of ammonia. 3. White precipitate forms with sodium-hidroxide, which can be dissolved in excess of sodium-hidroxide. Boiling the alkaline solution no change and no specific odour can be obderved. 4. White precipitate forms with perchloric acid from the original solution. 5. White precipitate forms with barium-chloride, which can not be dissolved in 20% HCl.

71 1. White crystalline compound, that dissolves in water. The solution is colorless and acidic. Excluded ions: Cu(II), Co(II), Ni(II), Cr(III), Fe(II), Fe(III), Mn(II)

72 1. White crystalline compound, that dissolves in water. The solution is colorless and acidic. Excluded ions: Cu(II), Co(II), Ni(II), Cr(III), Fe(II), Fe(III), Mn(II) 2. White precipitate forms with ammonia, which can not be dissolved in excess of ammonia. One of these ions must be: Hg(I), Hg(II), Pb(II), Bi(III), Sn(II), Sn(IV), Al(III), Mg 2+ No informations about: Ag +, Cd 2+, As(III), As(V), Ca 2+, Ba 2+, Na +, K +, NH + 4

73 3. White precipitate forms with sodium-hidroxide, which can be dissolved in excess of sodium-hidroxide. Boiling the alkaline solution no change and no specific odour can be obderved. Excluded ions: Ag +, Cd 2+, Hg(I), Hg(II), Bi(III),Mg 2+, NH 4 + Possible ions: Pb 2+ vagy Al 3+ No infos: As(III), As(V), Ca 2+, Ba 2+, Na +, K +

74 4. White precipitate forms with perchloric acid from the original solution. K +

75 4. White precipitate forms with perchloric acid from the original solution. K + 5. White precipitate forms with barium-chloride, which can not be dissolved in 20% HCl. SO4 2!, excluded ions Pb 2+, Ca 2+, Ba 2+ Possible ion Al 3+, and no infos about As(III), As(V), Na +. Substance:KAl(SO 4 ) 2

76 How many iron(ii)-chloride can be dissolved in a mixture of 50 cm mol/dm 3 acetic acid and 50 cm mol/dm 3 sodium-hidroxide? MM(iron(II)-chloride)=127 g/mol, K sp = K s (acetic acid) =

77 How many gramms of sodium-hydroxide (MM=40) is dissolved in 100 cm 3 of 0.25 mol/dm 3 acetic acid if the ph is 5.0? What is the solubility of the ZnS in this solution after saturating with H 2 S (c H2 S = 0.1 mol/dm 3 )? K sp = K a (acetic acid)= K a1 (H 2 S)= 10 7 K a2 (H 2 S)= 10 13