Final answer:
In the reaction of KHP with NaOH, besides water, the other product formed is Na2HPO4 (option d), which is a result of the neutralization reaction between a weak acid and a strong base.
Step-by-step explanation:
The question is regarding the product formed when potassium hydrogen phthalate (KHP) reacts with sodium hydroxide (NaOH). The expected products of such a neutralization reaction would be a salt and water. Based on the provided reaction and subsequent equilibrium reactions, we are led to consider the behavior of the conjugate base of the acid involved (HPO42-), which has amphiprotic properties. This means it can act as both an acid and a base.
Given the information about the amphiprotic nature of HPO42- and the relative strengths of its acid dissociation constants, we can infer that the substance acting as the base in the below reaction is HPO42-. When reacted with NaOH, KHP would ultimately yield Na2HPO4 and water. This aligns with the general reaction where a strong base reacts with a weak acid. Therefore, the correct answer for the product besides water is (d) Na2HPO4.