Sodium acetate conjugate acid-base dissociation

A simple buffer solution can be prepared by adding comparable molar amounts of acetic acid (CH3COOH) and its salt sodium acetate (CHsCOONa) to water. The equilibrium concentrations of both the acid and the conjugate base (from CHsCOONa) are assumed to be the same as the starting concentrations (see p. 715). A solution containing these two substances has the ability to neutralize either added acid or added base. Sodium acetate, a strong electrolyte, dissociates completely in water ... 

This time a solid sample of a weak base is being added to a solution of its conjugate acid. We let represent the concentration of acetate ion from the added sodium acetate. Notice that sodium acetate is a strong electrolyte, completely dissociated in aqueous solution. 

Suppose we have a weak acid solution, and to this we add its sodium salt, such as acetic acid and sodium acetate. The pH of the acetic acid solution will increase because a common ion, acetate, shifts the equilibrium of acetic acid dissociation toward its undissociated form, thus removing protons from solution and making it more alkaline. We now have a mixture of a weak acid and its conjugate base. 

We have seen that the conjugate base provided by salt dissociation is actually involved in the buffering action. The metal ions (like Na in sodium acetate) are not involved. We should therefore rewrite the definition of buffer solutions. Buffers are mixtures of weak acids and their coryugate bases. 

Every buffer consists of a buffer pair. In most cases the components are a weak acid and its salt. To make a buffer solution, a weak acid in solution is mixed with a salt of its conjugate base (e.g. acetic acid and sodium acetate). The resultant chemical reactions in solution are shown in Table 1.2. Since the acid is weak, it only partially dissociates, as shown in reaction 1 of Table 1.2. The... 

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