General Rules of Solubility

•Inorganic (examples)

  1. If both the cation and anion of an ionic compound are monovalent, the solute-solute attractive forces are usually easily overcome, and therefore these compounds are generally water soluble (NaCl, LiBr, KI)

  2. If both the cation and anion are multivalent, the solute-solute interaction may be too great to be overcome by the solute-solvent interaction and the compound may have poor water solubility (CaSO4, BaSO4)

  3. Salts of alkali metals (Na, K, Li) – usually water soluble

 

  4.  Ammonium and quaternary ammonium salts – water soluble

  5.  Nitrates, nitrites, acetates, chlorates, lactates – generally water soluble

  6.  Sulfates, sulfites, thiosulfates – generally water soluble

  7.  Acid salts of corresponding insoluble salt – tend to be more water soluble than original salt

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  8.  Hydroxides and oxides – generally water insoluble

  9.  Sulfides – generally water insoluble

  10.  Phosphates, carbonates, silicates, borates, hypochlorites – generally water insoluble

•Organic

  1. Molecules with one polar functional group--Usually soluble to total chain lengths of five carbons

  2. Branched chains--More soluble than straight chained

  3. Decrease in water solubility with an increase in molecular weight

  4. Increased structural similarity between solute and solvent is accompanied by an increased solubility

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