Question

What is an acid? What is a base?

Answer 1

See below.

Explanation:

According to the definition of Brønsted-Lowry, an Acid is a molecule that is capable to donate a proton `H^+` in solution, and a Base is a molecule that is capable of accepting an `H^+` ion.

A general reaction for an acid dissociation in water is:
`HA(aq)+H_2O(l)->H_3O^+(aq)+A^(-)(aq)`

A general reaction of a base with an acid is:
`B(aq)+H^+(aq)->BH^+(aq)`

For more details on acids and bases, please watch this video:
Acids & Bases | Nature, Strength & pH Scale.