Editing Sulfate (section)

==Properties==
There are numerous examples of ionic sulfates, many of which are highly [[solubility|soluble]] in [[water]]. Exceptions include [[calcium sulfate]], [[strontium sulfate]], [[lead(II) sulfate]], [[barium sulfate]], [[silver sulfate]], and [[mercury sulfate]], which are poorly soluble. [[Radium sulfate]] is the most insoluble sulfate known. The barium derivative is useful in the [[gravimetric analysis]] of sulfate: if one adds a solution of most barium salts, for instance [[barium chloride]], to a solution containing sulfate ions, barium sulfate will precipitate out of solution as a whitish powder. This is a common laboratory test to determine if sulfate anions are present.

The sulfate ion can act as a ligand attaching either by one oxygen (monodentate) or by two oxygens as either a [[chelate]] or a bridge.<ref name=greenwood/> An example is the complex {{chem2|[[Cobalt|Co]]([[Ethylenediamine|en]])2(SO4)]+Br−}}<ref name=greenwood/> or the neutral metal complex {{chem2|[[Platinum|Pt]]SO4([[Triphenylphosphine|PPh3]])2]}} where the sulfate ion is acting as a [[denticity|bidentate]] ligand. The metal–oxygen bonds in sulfate complexes can have significant covalent character.