If you add a small amount of hydrochloric acid to 4 liters of water, you would expect to have an acidic solution. Hydrochloric acid is a strong acid, which means that it completely dissociates in water to form hydrogen ions (H+) and chloride ions (Cl-). The hydrogen ions will react with the water molecules to form hydronium ions (H3O+), which are responsible for the acidic properties of the solution. The concentration of hydrogen ions in the solution will depend on the amount of hydrochloric acid that you add.