Final answer:
Potassium acetate in Buffer N3 serves a buffering role, reacting with added strong acids or bases to keep the pH level stable by maintaining the balance between a weak acid and its conjugate base.
Step-by-step explanation:
The role of potassium acetate in Buffer N3 relates to how buffers maintain pH levels. Similar to a sodium acetate/acetic acid buffer, potassium acetate works in conjunction with a weak acid to regulate the pH level. When a strong acid or base is added to a solution containing a buffer, the buffer's components react to keep the hydronium ion concentration, and thus the pH, relatively stable.
This is due to the equilibria that exist between a weak acid and its conjugate base. For example, if a strong base is added to an acetic acid/sodium acetate buffer, hydroxide ions (OH-) would react with the acetic acid (HC2H3O2) to form water (H2O) and acetate ions (C2H3O2-), minimizing changes in pH.
Conversely, the addition of a strong acid would lead to hydronium ions (H+) combining with acetate ions to form more acetic acid, again limiting pH fluctuations. Potassium acetate in Buffer N3 would similarly provide buffering action by contributing to the concentration of acetate ions available to react with added acids or bases.