Final answer:
Benzocaine precipitates during neutralization because it is a slightly soluble electrolyte that, once it surpasses the solubility product in the reaction, begins to precipitate out of the solution until equilibrium is reached.
Step-by-step explanation:
Benzocaine precipitates during neutralization because it is a slightly soluble electrolyte which, upon neutralization, can exceed the solubility product (Ksp), leading to precipitation. In a neutralization reaction, a base is added to an acid to form water and a salt. If the resulting salt has low solubility in water, it will begin to precipitate out of the solution. This is due to the fact that the reaction quotient (Q) becomes larger than the Ksp, indicating a supersaturated solution. Precipitation continues until Q equals the Ksp, reaching an equilibrium state where the solution is saturated, and no further precipitation occurs unless the conditions change.
For example, benzoic acid, when neutralized, forms benzoate salts, which are less soluble in an aqueous medium. This decreased solubility at a certain ionic concentration causes the benzoic acid to precipitate upon neutralization.