【How-to】Which compound releases hydronium ions in an aqueous solution

This means that a small amount of ions will form in pure water. Some molecules of H₂O will act as acids, each donating a proton to a corresponding H₂O molecule that acts as a base. Thus, the proton-donating molecule becomes a hydroxide ion, OH^–, while the proton-accepting molecule becomes a hydronium ion, H₃O⁺.