Silver Group
P166 #1, 2, 4, 6, 7, 9a, 12, 15, 23
1. Ag+ + Cl-  AgCl
2Hg1+ + 2Cl-  Hg2Cl2
Pb2+ + 2Cl-  PbCl2
PbCl2Pb2+ + 2ClPb2+ + SO4 2-  PbSO4
Pb2+ + CrO4 2-  PbCrO4
Hg2Cl2 + NH4+ +OH-  Hg + HgNH2Cl
AgCl  Ag+ + ClAg+ + NH4+ + OH-  Ag(NH3)2+
Ag(NH3)2+ +Cl-  AgCl + NH4+
2.
SO4 would crash out Pb2+, BaSO4
CO3 would crash out all of them
Cl- would crash out Pb2+ and Ag+
That leaves nitrate or acetate salts
4. PbSO4 , Ag2SO4 and Hg2SO4 are only slightly soluble and will crash out of solution
6.
a) ppt with cold HCl
b) PbCl2 is soluble in hot water. AgCl and Hg2Cl2 are not and would remain solid
c) NH4OH will cause Hg to form a gray white solid and Ag to form a soluble complex ion
7.
a) Hot HCl would dissolve Pb. Thus it couldn’t be separated from the other ions
b) false positive later
c) Ag and Hg start dissolving
d) too acidic to ppt HgNH2Cl
e) wouldn’t acidify enough to neutralize the NH3 that is coming off the complex ion. The reaction needs to be
shifted to that NH3 is being neutralized, removed, so more will come off the soluble complex ion and leave the
insoluble AgCl behind.
9. * AgNO3 and Zn(NO3)2 could be separated by adding HCl to ppt the silver
*K2CrO4 and KNO3 could be separated by adding Pb(NO3)2 to ppt PbCrO4
*HCL and HNO3 could be separated by adding AgNO3 to ppt AgCl
*Pb(NO3)2 and Hg(NO3)2 could be separated by adding hot HCl to dissolve the Pb and ppt Hg2Cl2
*H2SO4 and HCl could be separated by adding Ba(NO3)2 to ppt BaSO4
*Hg(NO3)2 (is a solid) and Hg2(NO3)2 (is aqueous) could be separated by adding NH4OH to ppt Hg
*Ag(NH3)2Cl and AgNO3 could be separated by adding HNO3 to ppt the AgCl
12. cold HCl, white ppt tells me it’s Ag, Hg or Pb
Insoluble in hot water means it’s not Pb
Insoluble in NH4OH means it must be Hg. Ag forms a soluble complex with NH4OH
15. 6MHCl, white ppt means again it’s Ag, Hg, or Pb
Washing in cold water could leave Ag or Hg
Only hot NH3 would allow Hg to be the only ion remaining
23. Less than. Stable complex forming means less ions in solution so the reaction will shift towards ions to compensate
for the ones being used to make the complex. Those ions have to come from somewhere so more solid dissolves to
create more ions