Substances that when placed in water, will dissociate to produce H+ ions.
Substances that when placed in water will dissociate to yield OH- ions.
Any substance that can transfer a proton (H+) to another substance
Any substance that can accept a proton from another substance
Acid and Base Strength:
In a reaction, look at the bases on both sides of the equation. Think of them as "competing" for protons. More of the protons will get transferred to the stronger base.
An acid that is almost 100% dissociated when in solution.
the equilibrium lies almost completely to the right. (There are only a negligible amount of undissociated H—A molecules.
Dissociation of an Arrhenius acid H—A gives H+ ions in aqueous solution. However, the bare proton is much too reactive to exist in aqueous solution where you have all those exposed electrons on the oxygen atoms. So the proton bonds to form H3O+ ions.
Dissociation of Water:
Always remember: the product of the H3O+ and OH- concentrations in aqueous solution is always 1.0*10-14 (at 25 deg C).
Kw = [OH-] [H3O+] = 1*10-14
pH = -log (concentration of H3O+)
EG: If you have [H3O+] = 1*10-3, pH = +3
EG: What is the pH of a 0.025M solution of HNO3?
Lewis Acids and Bases:
Lewis proposed an even more general definition of acids and bases. He said that an Acid is anything that can accept electrons. (A base is anything that donates electrons).
For example, when a bare proton forms a bond with a base such as ammonia, it is accepting the free elctrons from the ammonia to form a new covalent bond. That makes the proton an acid.
Lewis acids are more general because they include all molecules that can accept electrons—not just protons. (For example, Al3+ would be considered a Lewis acid).
AWOS: Anything with vacant valence orbitals can act as a Lewis Acid.