Use these relationships to determine whether a double displacement
reaction will result in the formation of a precipitate (ppt).
Keep these relationships in mind as we are doing qualitative analysis.
||All chlorides, bromides, and iodides are soluble except those containing
Ag+, Pb2+, or Hg22+.
||All compounds containing NO3-, ClO4-,
ClO3-, and C2H3O2-
anions are soluble.
||All sulfates (SO4-2) are soluble except those containing Hg22+,
Pb2+, Sr2+, Ca2+, or Ba2+.
||All compounds containing alkali metal cations (Na+, K+, H+) and the
ammonium ion (NH4+) are soluble
||All compounds containing OH-, PO43-, S2-,
CO32-, O2-,CrO4-2 and SO32-ions are
insoluble, unless the cation is from Rule 4. (Rule 4 is stronger than Rule 5)
Solubility reactions. A double displacement reaction will "fail" if
- One or more of the reactants are insoluble. Example: PbS
+ AgNO3 --> Fails by rule 5 S2- compounds are
insoluble. No reaction.
- If both products are soluble. Example: NaCl
+ HC2H3O2 --> NaC2H3O2 + HCl
No reaction. No ppt. Rule 2 and Rule 4