Answer:
See explanation and image attached
Step-by-step explanation:
Esterification is a reaction of an alkanol and an alkanoic acid to yield an ester and water as products. It is analogous to inorganic neutralization reaction.
The process may be acid catalyzed. As mentioned in the question, the process of ester formation between pentanoic acid and n‑propanol first involves the carbonyl in going through an sp3 hybridized intermediate before returning to sp2 hybridized state in the product.
The image of the neutral form of this intermediate as well as the final structure of the ester are both shown in the image attached to this answer.