ABSTRACT
The dissolution of some solids produces only neutral aqueous species. Very few minerals always dissolve as simple salts. Three examples of other natural minerals that behave as simple salts under some conditions are gypsum, cotunnite, and mirabilite. Ferrihydrite is sometimes called hydrated ferric iron oxide. It is generally true that when a metal hydroxide or oxyhydroxide is dehydrated, the result is a metal solid that is less soluble than the hydrated form. The presence of a solubility minimum is exhibited by most metal oxides, hydroxides, and oxyhydroxides. For a particular speciation that results when initially pure water is equilibrated with a given metal hydroxide, oxide, or oxyhydroxide, one needs to consider the concentrations of all of the metal-containing species. Acidic consumer cleaning products less hazardous than hydrochloric acid have been developed for removal (by acid dissolution) of mineral deposits.
