SO42ioniin
SO42ioniin, commonly known as the sulfate ion, is the chemical species with formula SO4^2−. It is a tetrahedral oxoan anion of sulfur in oxidation state +6. In the sulfate ion, the four oxygen atoms are equivalent by resonance, yielding four S–O bonds of essentially equal character. The overall charge is −2, and the ion is typically encountered in aqueous solutions as a stable constituent of many salts.
In water, sulfate is the conjugate base of sulfuric acid; the second dissociation has a pKa around
Occurrence and applications: SO4^2− occurs widely in nature in minerals such as gypsum (CaSO4·2H2O) and anhydrite
Safety and handling: sulfate itself has relatively low acute toxicity, but very high levels can cause digestive