$3\text{ mL}$ of ethanol is taken in a test tube and warmed gently in a water bath. A $5\%$ solution of alkaline potassium permanganate is added first drop by drop to this solution, then in excess.

(i) How is $5\%$ solution of $\mathrm{KMnO_4}$ prepared?

(ii) State the role of alkaline potassium permanganate in this reaction. What happens on adding it in excess?

(iii) Write chemical equation of this reaction.

(i) A $5\%$ solution of potassium permanganate is prepared by dissolving $5\text{ g}$ of solid potassium permanganate ($\mathrm{KMnO_4}$) in water to make a total volume of $100\text{ mL}$ of solution.

(ii) Role: Alkaline potassium permanganate acts as an oxidising agent because it provides oxygen to convert ethanol into ethanoic acid.

Observation in excess: When added drop by drop, the purple color of $\mathrm{KMnO_4}$ disappears as it reacts with ethanol. However, when added in excess, the purple color of the solution persists because all the ethanol has been completely oxidised to ethanoic acid, leaving no more ethanol to react with the additional $\mathrm{KMnO_4}$.

(iii) The chemical equation for the reaction is:

$$\mathrm{CH_3CH_2OH \xrightarrow{\text{Alkaline } KMnO_4 + \text{Heat}} CH_3COOH}$$