Final answer:
Adding sodium acetate to acetic acid increases the pH due to the common ion effect, resulting in a more basic solution. Sodium acts as a spectator ion, while acetate ions can hydrolyze to form OH- ions, thereby increasing pH.
Step-by-step explanation:
When sodium acetate is added to a solution of acetic acid, the pH does not decrease; rather, it increases due to the common ion effect. This is because the sodium ion (Na+) acts as a spectator ion and does not affect the equilibrium position. Upon addition of sodium acetate, a new equilibrium is established in which the concentration of hydrogen ions [H+] is lower compared to the initial state. As a result, because the [H+] concentration has decreased, the pH of the solution becomes higher. Therefore, adding sodium acetate, which is a salt of the conjugate base of acetic acid, actually increases the pH, causing the solution to be more basic.
Moreover, the addition of a strong acid such as HCl, however, would increase the H+ concentration, shifting the equilibrium to the left and thereby lowering the pH. On the contrary, sodium acetate dissociates in water to produce inert sodium ions and acetate ions, with the latter capable of hydrolyzing to form OH- ions, making the solution basic. Therefore, the solution of sodium acetate is rightly characterized as a basic solution.