Explain strong acid and weak acid and also illustrate with examples.

Acids (and bases) are classified into strong or weak ones
depending upon their degree of dissociation (ionization) in solution. Those having
strong tendency to ionize are called strong acids and those having lesser tendency to
ionize are weak acids. Infact strong acids remain completely ionized in solution (degree
of ionization = 100%). HCl, H2SO4, HNO3 and HClO4 – these four acids are strong. Organic
carboxylic acids, e.g. aetic acid, oxalic acid, citric acid or salicylic acid, on the
other hand, ionize partially in solution, hence they are called weak acids. Their
relative strength (or weakness) can be expressed in terms of the acid dissociation
constant Ka which is the equilibrium constant for the ionization
reaction

CH3COOH = CH3COO- +
 H+

Thus oxalic acid with Ka(1) = 5.8×10˄-2 is a relatively
stronger acid than acetic acid (Ka = 1.8×10˄-5).