Page 182 - Basic physical chemistry for the atmospheric sciences

(d) Formation constants (Kr ) f or some complex ions. All o f the ions are in aqueous solutions at
25°C and I atm. Some o f the data are quite uncertaina

Complex ion Equilibrium reaction K r
AgCI; AgCl(s) + c 1 - � A gCI; 2.0 x 1 0 - 5
CuC12 - CuCl(s) + c1 - � C uC12 - 1 . o x 1 0 - 1
CuCI� - cuc12 + c 1 - � c uc1 � - 5 x 1 0 5
HgSi - HgS(s) + s2 - � Hgs� - 4.0 x J 0 °
ZnCJ + Zn2 + + c 1 - � z nc1 + 1 . o x 1 0 1
cuc1 + cu2 + + c 1 - � c uc1 + 1 . o x 1 0 1
ZnF + Zn2 + + F - � Z nF + 2.o x 1 0 1
2
PbCI + Pb + + C l - � PbCI + 3 . 0 x 1 0 1
FeCl2 + Fe3 + + c 1 - � F eCl2 + 3 . 0 x 101
Snc1 + Sn2 + + c 1 - � S nCJ + 6.3 x 1 0 1
°' 2 3
00 {Cu(C0 3 )i}2 - CuC03(aq) + C o� - �{Cu(C03)i } - 1 . 6 x 1 0
SnF+ Sn2 + + c1 - � S nF + 7.7 x 1 0 4
sns � - SnSz(s) + s2 - � SnS� - 1 . 0 x 1 0 5
2
3
FeF2 + Fe + + F - � F eF + 1 . 6 x 1 0 5
AIF2 + AJ3 + + F - � A lF2 + 1 . 6 x 106
{Ag(NH )i}+ Ag + + 2 NH3(aq)�{Ag(NH3 )i} + 1 . 6 x 1 0 7
3
{Ni(NH3)6}2 + Ni2 + + 6 NH3 � { Ni(NH 3 )6}2 + 5.5 x 1 0 8 3
{Cu(NH 3 ) }2 + Cu2 + + 4 N H 3 � {Cu(NH3)4}2 + I . I x 1 0 1
4
3
Ag(S 0 H - Ag + + 2S 0 2 � - � A g(S20 )� - 1 . 7 x 1 0 1 3
3
2
{Ag(CN)i} - Ag + + 2 CN - � { Ag(CN)i} - 5.6 x 1018
2
{Cu(CN)4}2 - Cu2 + + 4CN - �{Cu(CN)4} - 1 . 0 x 1 0 25
37
{Fe(CN)6}4- Fe2 + + 6 CN - � { Fe(CN) }4 - l Q 4
6
3
3
{Fe(CN)6} - Fe + + 6 cN - � { Fe(CN)6}3 - i . O x 1 0 2
a The equilibrium constant for the formation of a complex ion from a metal ion in aqueous solution is called
the f o rmation constant (Kr) of the complex ion. The higher the value of Kr the more stable is the complex
ion - see Section 5. 1 1 .