Acidity refers to how much acid is present in a substance, or its ability to donate protons (H+ ions).
Refers to the tendency of an acid, symbolized as HA, to dissociate into a proton, H+, and an anion, A-.
Hydronium Ion Concentration [H3O+]: The amount of hydronium ion in a solution determines its acidity level.
pKa Value: It's another way chemists talk about acidity; lower pKa values mean higher acidity.