Final answer:
An Arrhenius acid or base is always a Brønsted-Lowry acid or base because it involves the donation or acceptance of protons, congruent with Brønsted-Lowry definitions.
Step-by-step explanation:
An Arrhenius acid is defined as a substance that dissociates in water to produce hydrogen ions (H+), while an Arrhenius base dissociates to produce hydroxide ions (OH-). The Brønsted-Lowry theory expands on this by defining acids and bases in terms of their ability to donate or accept protons (H+ ions).
According to the Brønsted-Lowry theory, an acid is a proton donor, and a base is a proton acceptor. It's essential to note that while every Arrhenius acid and base is also a Brønsted-Lowry acid and base, not all Brønsted-Lowry acids and bases fit the Arrhenius definition. This is because Brønsted-Lowry acids and bases are defined based on their ability to donate or accept protons, rather than the presence of specific ions.