Table 4 Selected thermodynamic data for the Fe–S, Zn–S, Cu–S, and Cd–S systems

65

Amorphous Fes

20

FeS + H⁺ = Fe²⁺ + HS^-

-3.00

FeS + H⁺ + HS = Fe(HS)₂°

+ 3.45

51

Crystalline sphalerite

25

ZnS + H₂S°= Zn²⁺ + 2HS^-

-18.47

ZnS + H₂S°= Zn(HS)₂°

-5.65

ZnS + 2HS^- = ZnS(HS)₂^2-

-5.33

ZnS+H₂S °+2HS^- = Zn(HS)₄^2-

-3.83

ZnS + HS^-ZnS(HS)^-

-4.64

52

Crystalline sphalerite

25

ZnS + H₂S°= Zn(HS)₂°

-5.3

ZnS + H₂S°+ HS^- = Zn(HS)₃^-

-3.3

ZnS +H₂S °+ 2HS^- = Zn(HS)₄^2-

-3.4

ZnS + H₂O+HS^- = Zn(OH)(HS)₂^-

-4.4

ZnS +H₂O+2HS^- = Zn(OH)(HS)₃^2-

4.9

53

Amorphous ZnS

25

ZnS + H⁺ = Zn²⁺ + HS^-

-10.89^a

ZnS + H₂O = Zn(OH)(HS)°

-5.87

54

Crystalline covellite, CuS

25

CuS + H⁺ = Cu²⁺ + HS^-

-20.95

CuS + 2HS^- = CuS(HS)₂^2-

-4.97

CuS + 3HS^- = CuS(HS)₃^3-

-4.04

CuS + 4S(s) + HS^- = CuS(S₅)^2- + H⁺

-12.19^b

CuS + 6.5S(s) + 1.5HS^- = CuS₄S₅^3- + 1.5H⁺

-15.71^c

CuS + 7.5S(s) 1.5HS^- = Cu(S₅)₂^3- + 1.5H⁺

-16.06^c

55

Crystalline chalcocite, Cu₂S

22

Cu₂S + H⁺ = 2Cu⁺ + HS^-

-34.62

0.5Cu₂S + 1.5HS^- + 0.5H+ = Cu(HS)₂^-

-0.13

Cu₂S + 2HS^- = Cu₂S(HS)₂^2-

-4.75

10

Crystalline greenockite (gr) and two amorphous precipitates (al and a2)

25

CdS(gr) + H⁺ = Cd²⁺ + HS^-

-14.82

CdS(al) + H⁺ = Cd²⁺ + HS^-

-14.40

CdS(a2)+H⁺ = Cd2⁺+HS^-

-14.15

Cd²⁺+HS^- = Cd(HS)⁺

+7.38

Cd²+2HS^- = Cd(HS)₂°

+14.43

Cd²+3HS^- = Cd(HS)₃

+16.28

Cd²+4HS^- = Cd(HS)₄^2-

+18.43

63

Crystalline greenockite

25

CdS + H⁺ = Cd²⁺ + HS^-

-14.36

Cd²⁺ + 3HS^- = Cd(HS)₃^-

+16.44

Cd²⁺ + 4HS^- = Cd(HS)₄^2-

+17.89

Cd²⁺+HS^-+H₂O = CdOHS^-+2H⁺

-2.47

62

Amorphous CdS

25

CdS + H⁺ = Cd²⁺ + HS^-

-12.28^d

Cd²⁺+HS^- = Cd(HS)⁺

+7.55

Cd²⁺+2HS^- = Cd(HS)₂°

+14.61

Cd²⁺+3HS^- = Cd(HS)₃^-

+16.49

Cd²⁺+4HS^- = Cd(HS)₄^2-

+19.35