What are the precipitation rules (what is the solubility table)?
In a word question or chemical equation you will not always be shown whether a chemical is SOLUBLE (aq) or INSOLUBLE (s). Sometimes you will have to determine that for yourself. For this reason we turn to what they call the PRECIPITATION RULES or the SOLUBILITY TABLE. It is the simplest way to visualize, organize, and memorize the precipitation rules.
I also created an expanded solubility table that includes more ions you might see and work with in class. Typically they are only seen in AP and college courses and sometimes not even then.
MEMORIZATION TRICK: In AP or college classes you may have to memorize the solubility table. If you only memorize the ions that are soluble, you only have to memorize half or less of the solubility table. DO NOT focus on the exceptions. Memorize the general ions first.
Make sure before you try to understand the examples and practice problems below that you know how to break apart and put together ionic compounds. If you have any questions on ionic compounds refer to the sections on how to form ionic compounds and how to break apart ionic compounds. In the examples I will point out and use the RARE exceptions in the solubility table. However, with practice problems and future use of these ideas I WILL NOT require the RARE exceptions to be known for the solubility table.
Examples: Determine if the chemical is INSOLUBLE or SOLUBLE and give what state it would be marked with in a chemical equation (aq or s). Make sure to use the solubility table and precipitation definitions if you need them. Another useful tool is the ion periodic table. VIDEO Solubility Table Examples 1.
Chemical | Answer |
NaNO3 | Soluble (aq) |
RuPO4 | Insoluble (s) |
Mn3(SO4)2 | Soluble (aq) |
V(OH)2 | Insoluble (s) |
(NH4)2CO3 | Soluble (aq) |
Li3PO4 | Soluble (aq) |
AgCl | Insoluble (s) |
CaS | Soluble (aq) |
PRACTICE PROBLEMS: Determine if the chemical is INSOLUBLE or SOLUBLE and give what state it would be marked with in a chemical equation (aq or s). Make sure to use the solubility table and precipitation definitions if you need them. Another useful tool is the ion periodic table.
Chemical | Answer |
MoI | Soluble (aq) |
CaSO4 | Soluble (aq) |
Zr3(PO4)2 | Insoluble (s) |
W(CO3)2 | Insoluble (s) |
NH4OH | Soluble (aq) |
Fe2S3 | Insoluble (s) |
Cs2CO3 | Soluble (aq) |
FrOH | Soluble (aq) |