ethanol gives haloform reaction because it is oxidized to acetaldehyde whose alpha carbon donates a hydrogen atom for the formation of haloform

CaOCl2+ H2O=Ca(OH)2+Cl2

The chemistry of acetyl chloride is not as a methyl ketone but as an acyl halide. All the action is on the carbon atom with the oxygen and chlorine. In the haloform reax the methyl carbon gets attacked losing a proton, picking up a halide and leaving an OH behind to form an acid and a haloform.

BY HALOFORM TEST

Acetone gets oxidized by bleaching powder. Chloroform is one of the products of the reaction.

I have this same question! All i know is that it is to acidify the solution by protonating the hypochlorite ion and turning it into hypochlorous acid. Hope that helps!