An example of an Arrhenius acid is hydrochloric acid (HCl). When HCl dissolves in water, it donates a hydrogen ion (H+) to the water, resulting in the formation of hydronium ions (H3O+) and chloride ions (Cl-). The higher the concentration of H+ ions in a solution, the more acidic the solution is. Arrhenius acids are characterized by their ability to release H+ ions in water, and they play a crucial role in various chemical reactions and industrial processes.