The strengths of photonic acids like HCI, HNO₃, H₂SO₄, HCN, HF can be compared by their tendencies to give protons. Acids like HCI, HNO₃ or H₂SO₄ are strong acids while CH₃COOH, HF, HCN are weak acids. Ionization of an acid in water measures the relative strength of the acid.

For instance ionization of an acid HA may be represented as
                                               HA   <==>   H⁺  +  A^-
The equilibrium constant of the reaction is written as
                                               K_a  = [ H⁺] [ A ^-]
                                                            [ HA ]
Where Ka is known as dissociation constant or ionization constant of an acid and measures the relative strength of an acid. The stronger the acid, the larger will be is K_a .

The term pk_a that is, - long k_a is commonly used to express the dissociation of an acid.
                                               pk_a = - log k_a  =  1
                                                                          log k_a 
Thus the higher the value pk_a, the weaker the acid.
Similarly the ionization equilibrium of bases can be studied. Consider the ionization of base MOH:
                                                   MOH  <==>   M⁺ +  OH^-
The equilibrium content may be expressed as
                                                   k_b = [M+ ] [ OH^- ]
                                                             [ MOH ]
Where kb is known as the ionization or dissociation constant of the base. It measures the relative strength of the base. The higher the value of k_b, the stronger is the base.

k_b may be expresses as
                                                  pk_b  = - log k_b =  1
                                                                             log k_b
Larger the value of pkb, lesser is the dissociation and weaker is the base

For more help in Strength Of Acids And Bases click the button below to submit your homework assignment