The formula of ethanol is `CH_(3)CH_(2)OH` whereas that of ethanoic acid is `CH_(3)COOH`. These formulae show that a molecule of ethanol contains only 1 oxygen atome (O) whereas a molecule of ethanoic acid contains 2 oxygen atoms `(OO)`.This means that oxygen is added during the conversion of ethanol into ethanoic acid. now, by definition, addition of oxygen to a substance is called oxidation. So the conversion of ethanol into ehtanoic acid is an oxidation reaction because oxygen is added to ethanol during this reaction.
