Here's why:

* Propyl butanoate is an ester, formed by the reaction of butanoic acid and propanol.

* Acid hydrolysis is the process of breaking an ester bond using water in the presence of an acid catalyst (like H⁺).

* The acid catalyst helps to protonate the carbonyl oxygen of the ester, making it more susceptible to nucleophilic attack by water.

* This attack results in the formation of a tetrahedral intermediate, which then breaks down to form the corresponding carboxylic acid (butanoic acid) and alcohol (propanol).

Reaction equation:

```

CH3CH2CH2COOCH2CH2CH3 + H2O → CH3CH2CH2COOH + CH3CH2CH2OH

```

In words:

Propyl butanoate + water → Butanoic acid + Propanol