Acid-base dissociation equilibria. Strength of acids and bases

16 ACID-BASE DISSOCIATION EQUILIBRIA. STRENGTH OF ACIDS AND BASES The dissociation of an acid (or a base) is a reversible process to which the law of mass action can be applied. The dissociation of acetic acid, for example, yields hydrogen and acetate ions  

Applying the law of mass action to this reversible process, we can express the equilibrium constant as 

The constant K is termed the dissociation equilibrium constant or simply the dissociation constant. Its value for acetic acid is 1-76 x 10 5 at 25°C. 

In general, if the dissociation of a monobasic acid HA takes place according to the equilibrium 

The stronger the acid, the more it dissociates, hence the greater is the value of K, the dissociation equilibrium constant. 

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