5.7: Predicting Solubility Trends
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- 79775
The solubility of many simple ionic compounds can be predicted by applying the set of rules shown below.
- Salts of the alkali metal ions and the ammonium ion, Li+, Na+, K+, and NH4+ are almost always soluble.
- Virtually all metal nitrates and metal acetates are soluble.
- Metal halides are generally soluble, except for salts of Ag+, Pb2+, Cu+ and Hg+.
- Metal sulfates are generally soluble, except for salts of Ba2+, Pb2+ and Ca2+.
- With exception of the alkali metal ions and ammonium (Rule 1), the following salts are generally insoluble: metal carbonates (CO32-), metal phosphates (PO43-) and metal chromates (CrO42-).
- Metal hydroxides and metal sulfides are generally insoluble, except for those covered by Rule 1 and Ca2+, Sr2+ and Ba2+.
Applying these rules to the reaction between lead nitrate and potassium iodide, the reactants are both soluble (Rule 1 and Rule 2). In the products, potassium nitrate will be soluble (Rule 2) and lead iodide will be insoluble, based on Rule 3.
Exercise \(\PageIndex{1}\)
Mixing each of the following salt solutions results in the formation of a precipate. In each case, identify the insoluble salt.
- NaCl + Pb(NO3)2
- Fe(C2H3O2)3 + KOH
- Ca(NO3)2 + K2SO4
- Li2S + CuSO4
- Co(C2H3O2)2 + LiOH
Exercise \(\PageIndex{2}\)
For each of the ionic compounds given below, determine whether or not the compound will be soluble in water, according to the trends given above.
- AgNO3 ☐ soluble ☐ insoluble
- MgCl2 ☐ soluble ☐ insoluble
- Na2SO4 ☐ soluble ☐ insoluble
- AgCl ☐ soluble ☐ insoluble
- Ba(NO3)2 ☐ soluble ☐ insoluble
- PbI2 ☐ soluble ☐ insoluble
- Mg(NO3)2 ☐ soluble ☐ insoluble
- BaSO4 ☐ soluble ☐ insoluble
- FeCl3 ☐ soluble ☐ insoluble
- Pb(CH3COO)2 ☐ soluble ☐ insoluble
Contributors
Paul R. Young, Professor of Chemistry, University of Illinois at Chicago, Wiki: AskTheNerd; PRY
askthenerd.com - pyoung
uic.edu; ChemistryOnline.com