An acid is any species which increases the concentration$H^{+}$ ions in an aqueous solution.$^3$ $^1$
A base is any species which increases the concentration $OH^{-}$ ions in an aqueous solution.$^3$ $^1$
This is the definition of acids and bases that will be used for the rest of this text.
An acid is any species which acts as a proton donner.$^4$ $^1$
A base is any species which acts as a proton acceptor.$^4$ $^1$
An amphoteric substance is one that capable of acting as both an acid and a base.$^4$ $^1$
Examples: