precipitate

There are so many precipitates. Only the precipitates (insoluble in water) of the common metals, i.e. barium (Ba), calcium (Ca), magnesium (Mg), aluminium (Al), zinc (Zn), iron(Fe), lead (Pb), copper (Cu) and silver (Ag), are listed below.

Oxides:
MgO - white
Al2O3 - white
ZnO - white (yellow when hot)
FeO - black
Fe2O3 - reddish brown
Fe3O4 - black
PbO - yellow (orange/brown when hot)
CuO - black
Ag2O - brownish black

Hydroxides:
Ba(OH)2 - white (slightly soluble in water)
Ca(OH)2 - white (slightly soluble in water)
Mg(OH)2 - white
Al(OH)3 - white
Zn(OH)2 - white
Fe(OH)2­ - dirty green
Fe(OH)3 - brown
Pb(OH)2 - white
Cu(OH)2­ - blue
AgOH - white (very unstable, decomposed readily to give Ag2O)

Sulphates:
BaSO4 - white
CaSO4 - white
PbSO4 - white

Nitrates:
no precipitate

Chlorides:
PbCl2 - white (soluble in hot water)
AgCl - white