According to Bronsted-Lowry definitions, what is a Bronsted-Lowry acid?

A Bronsted-Lowry acid is defined as a substance that donates protons (H⁺ ions) in a chemical reaction. This concept is fundamental in acid-base chemistry, where the focus is placed on the transfer of protons between species. When a Bronsted-Lowry acid donates a proton, it results in the formation of its conjugate base.

For example, when hydrochloric acid (HCl) donates a proton to a water molecule, it forms hydronium (H₃O⁺) and chloride ions (Cl⁻). The ability to donate protons is the key characteristic that identifies a substance as a Bronsted-Lowry acid, distinguishing it from other definitions of acids that may focus more on properties like sour taste or corrosiveness.

In contrast, a proton acceptor is defined as a Bronsted-Lowry base, which means this option reflects the opposite concept. The terms 'electron donor' and 'anion' pertain to different areas of chemistry and do not align with the Bronsted-Lowry definitions. Thus, recognizing a Bronsted-Lowry acid as a proton donor is essential for understanding acid-base reactions in biochemical and chemical contexts.