Question

3ml of ethanol is taken in a test tube and warmed gently in a water bath. A $5\mathrm{\%}$ solution of alkaline potassium permanganate is added first drop by drop to this solution, then in excess. Write a chemical equation for this reaction.

Answer 1

Hint: We know that ethanol contains alcoholic functional groups. Alkaline potassium permanganate is a very strong oxidising agent. In the reaction, oxidation of ethanol occurs.

Complete step by step answer:
In the reaction, $3\text{ mL}$ of ethanol is taken in a test tube and warmed gently in a water bath. A $$5\mathrm{\%}$$ solution of alkaline potassium permanganate is added first drop by drop to this solution, then in excess.
$$5\mathrm{\%}$$ of alkaline potassium permanganate solution means that $5\text{ g}$ of potassium permanganate is added to $100\text{ mL}$ of water and then sodium carbonate solution is added to it.
Alkaline potassium permanganate is a very strong oxidising agent. Thus, potassium permanganate adds oxygen to the ethanol and converts ethanol to an acid. The acid formed in the reaction is acetic acid.
Initially when alkaline potassium permanganate is added drop by drop to ethanol solution, the purple colour of alkaline potassium permanganate disappears. This is because the coloured permanganate ions of alkaline potassium permanganate are consumed to oxidise ethanol solution.
When excess of alkaline potassium permanganate is added, the purple colour of alkaline potassium permanganate does not change. This is because there is no more ethanol left for the reaction.
The chemical equation for the reaction between alkaline potassium permanganate and ethanol solution is as follows:
$${\text{C}}_2{\text{H}}_5\text{OH}\stackrel{\text{Alkaline KMn}{\text{O}}_{\text{4}}+\text{Heat}}{\to }\text{C}{\text{H}}_3\text{COOH}$$

Note:
Alkaline solution of potassium permanganate is prepared by dissolving potassium permanganate in water and then adding sodium carbonate solution to it so that it becomes alkaline. Alkaline potassium permanganate is a strong oxidising agent. It provides nascent oxygen. The intermediate in this reaction is aldehyde or ketone which is further converted to acetic acid.