1. \( \mathrm{HS}^{-}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\mathrm{I}) \leftrightharpoons \mathrm{H}_{2} \mathrm{~S}(\mathrm{aq})+\mathrm{OH}^{-}(\mathrm{aq}) \)

The reaction you've presented showcases the behavior of bisulfide ions (\( \mathrm{HS}^{-} \)) in water, functioning as a weak acid. This system is a great demonstration of acid-base equilibria, where bisulfide can donate a proton (H\(^+\)) to water, generating hydrosulfide (\( \mathrm{H}_{2} \mathrm{S} \)) and hydroxide ions (\( \mathrm{OH}^{-} \)). It highlights the role of species in solutions and the dynamic balance between reactants and products. In real-world applications, this reaction is significant in environmental chemistry, particularly in natural water bodies where sulfur compounds may be present. The presence of \( \mathrm{HS}^{-} \) gives insight into the acidity of waters as well as the possible formation of hydrogen sulfide (\( \mathrm{H}_{2} \mathrm{S} \)), a compound of concern due to its toxicity and foul odor. Understanding this equilibrium can be essential for water treatment and management strategies.