CBSE Class 10 Science 2019 · Paper 31/1/1/C · Question 17(b)

(a) (i) Ethanol is heated with alkaline potassium permanganate (or acidified potassium dichromate): ${\text{CH}}_3{\text{CH}}_2\text{OH}\stackrel{{\text{alkaline KMnO}}_4+\text{heat}}{\to }{\text{CH}}_3\text{COOH}$. Name: oxidation. (ii) Ethene and hydrogen are passed over a nickel (or palladium) catalyst on heating: ${\text{CH}}_2={\text{CH}}_2+{\text{H}}_2\stackrel{\text{Ni, heat}}{\to }{\text{CH}}_3-{\text{CH}}_3$. Name: hydrogenation (an addition reaction). (iii) Ethanoic acid is warmed with ethanol and a few drops of concentrated sulphuric acid as catalyst: ${\text{CH}}_3\text{COOH}+{\text{CH}}_3{\text{CH}}_2\text{OH}\stackrel{{\text{conc. H}}_2{\text{SO}}_4}{\to }{\text{CH}}_3{\text{COOCH}}_2{\text{CH}}_3+{\text{H}}_2\text{O}$, giving the sweet-smelling ester ethyl ethanoate. Name: esterification. (b) Detergents can be used even in hard water: unlike soaps, they do not form an insoluble scum with the calcium and magnesium ions of hard water, so they still lather and clean.