Insoluble Definition (Chemistry)

What Does Insoluble Mean?

beaker full of water
Some substances may be insoluble in some cases; for example, water is insoluble in alcohol, but it is soluble in acid. Brian Edgar/Flickr/CC 2.0 SA

Insoluble means incapable of dissolving in a solvent. It is rare for absolutely no solute to dissolve at all. However, many substances are poorly soluble. For example, very little silver chloride dissolves in water, so it is said to be insoluble in water. Note a compound may be insoluble in one solvent yet fully miscible in another. Also, several factors affect solubility. One of the most important is temperature. Increasing temperature frequently improves the solubility of a solute.

Solutes Insoluble in Water

Examples of compounds that are considered insoluble in water are the:

  • Carbonates (except group I, ammonium, and uranyl compounds)
  • Sulfites (except group I and ammonium compounds)
  • Phosphates (except for some group 1 and ammonium compounds; lithium phosphate is soluble)
  • Hydroxides (multiple exceptions)
  • Oxides (multiple exceptions)
  • Sulfides (except group I, group II, and ammonium compounds)

Sources

  • Clugston M. and Fleming R. (2000). Advanced Chemistry (1st ed.). Oxford: Oxford Publishing. p. 108.
  • Hefter, G.T.; Tomkins, R.P.T (Editors) (2003). The Experimental Determination of Solubilities. Wiley-Blackwell. ISBN 978-0-471-49708-0.