Final answer:
A proton donor is a Brønsted-Lowry acid, which donates a proton to a base in an acid-base reaction.
Step-by-step explanation:
A proton donor is known as a Brønsted-Lowry acid. In an acid-base reaction, the acid donates a proton (H+) to a base. The species remaining after the acid donates a proton is called the conjugate base of the acid.
For example, water (H2O) can act as a Brønsted-Lowry acid and donate a proton under the right conditions. In the reaction H2O + H2 → H3O+ + OH-, water acts as the acid and donates a proton to form the hydronium ion (H3O+).
So, in summary, a proton donor is a Brønsted-Lowry acid, which donates a proton to a base in an acid-base reaction