Chemistry Reference
In-Depth Information
Notice that the title of the rules is “general
”
solubility rules. There are
exceptions to the rules listed there. For example, although ionic compounds
that contain halogens tend to be soluble, when the cation is lead (II) (as in
lead (II) chloride or lead (II) iodide) the ionic compound will be insoluble
in water. The rules listed are really meant to be general trends, which you
may want to memorize. They will give you the ability to make fast predic-
tions about the identity of a precipitate that is found after many ionic reac-
tions, just not the one in our first example.
When you have more time, or access to more specific information, such
as that shown in Figure 6-3a, you can make a much more accurate predic-
tion of the identity of a precipitate. If you find the cation (positive ion) on
the right-hand column and match it with the anion (negative ion) across
the top of the table, you will be able to discover the solubility of the prod-
ucts and the identity of the precipitate.
Solubility Table
Aluminum
S
S
-
S
S
-
I
S
S
I
S
d
Ammonium
SSSSSSSSSSSS
Barium
S
S
I
S
S
I
SSSI
I
d
Calcium
S
S
I
SSS SSSI
Sd
Copper (II)
S
S
I
S
S
I
I
-
S
I
S
I
Iron (II)
S
S
I
S
S
-
I
S
S
I
S
I
Iron (III)
S
S
-
S
SS
I
I
-
S
I
SS
d
Lead
S
SS
I
S
S
I
I
SS
S
I
I
I
Lead (II)
S
S
I
S
S
I
SS
I
S
I
I
SS
Magnesium
S
S
I
SSSI
SSI
Sd
Mercury (I)
SS
I
I
S
I
SS
-
I
S
I
SS
I
Mercury (II)
S
SS
I
S
S
SS
I
I
S
I
d
I
Potassium
SSSSSSSSSSSS
Silver
SS
I
I
S
I
SS
-
I
S
I
SS
I
Sodium
SSSSSSSSSSSS
Strontium
S
S
SS
S
S
SS
SSSI
SS
Zinc
S
S
I
SSSI
SSI
SI
Key:
S = Soluble
SS = Slightly Soluble
I = Insoluble
d = Decomposes
- = Unknown
Figure 6-3a
