Final answer:
An Arrhenius acid is a substance that produces hydrogen ions (H+) when ionized in an aqueous solution, like hydrochloric acid. An Arrhenius base produces hydroxide ions (OH-) in solution, such as sodium hydroxide.
Step-by-step explanation:
According to Svante Arrhenius, an Arrhenius acid is a substance that ionizes in an aqueous solution to produce hydrogen ions (H+). These ions are also known as protons. An example of an Arrhenius acid is hydrochloric acid (HCl), which ionizes in water to form H+ and Cl- ions. In contrast, an Arrhenius base is a substance that ionizes to yield hydroxide ions (OH-). For instance, sodium hydroxide (NaOH) dissociates in water to form Na+ and OH- ions.
There are several theories that define acids and bases, including the Brønsted-Lowry theory which defines acids as proton donors and bases as proton acceptors, and the Lewis theory of acids and bases, where acids accept electron pairs and bases donate them. However, it's the Arrhenius theory that introduces these definitions in terms of ion production in aqueous solutions.