Final answer:
The reaction involves the protonation of the carbonyl oxygen in acetone followed by nucleophilic attack of ethanol to form ethyl acetate.
Step-by-step explanation:
In the given reaction of acetone dissolved in dry ethanol bubbled with HCl (g), the mechanism involves the protonation of the carbonyl oxygen in acetone by HCl.
This is followed by nucleophilic attack of the ethanol molecule on the carbocation intermediate, resulting in the formation of ethyl acetate.
The complete mechanism for the reaction is:
Step 1: CH3COCH3 + HCl → CH3COCH3H+ + Cl-
Step 2: CH3COCH3H+ + C2H5OH → CH3COCH2C2H5 + H2O