Final answer:
In an acid-catalyzed hydration reaction, the third step is the deprotonation of the oxonium ion, where another water molecule removes the acidic proton, completing the addition of a water molecule across the alkene's double bond and restoring the acid catalyst.
Step-by-step explanation:
Step 3 of an Acid-Catalyzed Hydration Reaction Mechanism
The third step in drawing a mechanism for an acid-catalyzed hydration reaction involves thinking about the result of the previous steps. After the initial protonation of the alkene to form a more stable carbocation (Step 1) and the attack of water as a nucleophile on the carbocation (Step 2), the third step typically involves the deprotonation of the newly formed oxonium ion. At this point, another water molecule removes the acidic proton from the oxonium ion to give the final alcohol product. This step is crucial because it restores the catalyst (the acid) and completes the addition of a water molecule (H-OH) across the C=C bond of the alkene, which characterizes the hydration of alkene.