(a) What happens when propanoic acid is warmed with methanol in the presence of a few drops of concentrated sulphuric acid? Write equation of the reaction involved.
(b) What change will you observe if you test soap solution with a litmus paper (red and blue)? Give reason for your observation.
(c) What is meant by denatured alcohol? What is the need to denature alcohol?
(a) Propanoic acid will react with the alcohol in the presence of concentrated sulphuric acid to form esters.
CH3CH2COOH + CH3OH → CH3CH2COOCH3 + H2O
Propanoic acid Methanol Methyl propanoate water
(b) Red litmus paper turns blue in soap solution and no change occurs on blue litmus paper because soap is basic in nature.
(c) Denatured alcohol is ethyl alcohol which has been made unfit for drinking purposes by adding small amounts of poisonous substances like methanol, pyridine, copper sulphate etc. This is done to prevent the misuse of industrial alcohol for drinking purposes or black marketing (as it is supplied duty free for industrial purposes by the government).