Sodium thiosulfate
= Sodium thiosulfate
{title2=$\mathrm{Na_2S_2O_3}$}
<Sodium thiosulfate> is the salt $\mathrm{Na_2S_2O_3}$, often encountered as a hydrate. Its thiosulfate ion can participate in both oxidation-reduction reactions and metal-ion complex formation.
In photographic fixing, thiosulfate binds <silver> and helps dissolve residual <silver halide>. In analytical chemistry, reaction with iodine supports quantitative <titration>. These applications use different aspects of the same anion's chemistry.