Editing Solubility equilibrium (section)

=== Dissolution with reaction ===
[[File:Silver Chloride dissolution.png|thumb|220px| When a concentrated solution of ammonia is added to a suspension of silver chloride dissolution occurs because a complex of Ag<sup>+</sup> is formed]]
A typical reaction with dissolution involves a [[weak base]], B, dissolving in an acidic [[aqueous solution]].
<math display="block">\mathrm {B} \mathrm{(s)} + \mathrm H^+ \mathrm {(aq)} \leftrightharpoons \mathrm {BH}^+ (\mathrm{aq)}</math>
This reaction is very important for pharmaceutical products.<ref>{{cite web|url=http://www.pharmainfo.net/reviews/potential-solubility-drug-discovery-and-development |title=Potential Of Solubility In Drug Discovery And development |last=Payghan |first=Santosh |year=2008 |publisher=Pharminfo.net |access-date=5 July 2010 |url-status=dead |archive-url=https://web.archive.org/web/20100330171700/http://www.pharmainfo.net/reviews/potential-solubility-drug-discovery-and-development |archive-date=March 30, 2010 }}</ref> Dissolution of weak acids in alkaline media is similarly important.
<math display="block">\mathrm{ HA(s) + OH^-(aq) \leftrightharpoons A^- (aq) + H_2O}</math>
The uncharged molecule usually has lower solubility than the ionic form, so solubility depends on pH and the [[acid dissociation constant]] of the solute. The term "intrinsic solubility" is used to describe the solubility of the un-ionized form in the absence of acid or alkali.

Leaching of [[aluminium salt]]s from rocks and soil by [[acid rain]] is another example of dissolution with reaction: [[alumino-silicate]]s are bases which react with the acid to form soluble species, such as Al<sup>3+</sup>(aq).

Formation of a chemical [[Complex (chemistry)|complex]] may also change solubility. A well-known example is the addition of a concentrated solution of [[ammonia]] to a suspension of [[silver chloride]], in which dissolution is favoured by the formation of an ammine complex.
<math display="block">\mathrm{AgCl(s) + 2 NH_3(aq) \leftrightharpoons [Ag(NH_3)_2]^+(aq) + Cl^- (aq)}</math>
When sufficient ammonia is added to a suspension of silver chloride, the solid dissolves. The addition of [[water softener]]s to washing powders to inhibit the formation of [[soap scum]] provides an example of practical importance.