(a) How is ethanoic acid obtained from ethanol? Write down the chemical equation of the reaction involved.
(b) How would you distinguish between ethanol and ethanoic acid by chemical test?
(c) Explain the formation of scum when hard water is treated with soap.
(a) Ethanoic acid is obtained from ethanol by the means of oxidation reaction. When ethanol is heated with alkaline potassium permanganate solution for acidified potassium dichromate solution. It gets oxidised to ethanoic acid. It is called an oxidation reaction because oxygen is added to it during this conversion.
CH3CH2CH + 2[O]\(\underset{or\;acidifiedK_2Cr_2O_7}{\stackrel{Alkaline\; KMnO_4;Heat}{\longrightarrow}}\)\(CH_3COOH + H_2O\)
(b) Litmus test: Some blue litmus solution is added to the organic compound (to be tested). If the blue litmus solution turns red, it shows that the organic compound is acidic in nature and hence it is a carboxylic acid (ethanoic acid). Ethanol has no effect on any litmus solution.
(c) When soap is used for washing clothes with hard water, a large amount of soap in water reacts with the Calcium and magnesium ions of hard water to form an insoluble precipitate called scum. This makes the cleaning of clothes difficult.