CBSE Class 10 Science 2024: question 28

Hints

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Step-by-step solution

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1. It is an oxidation reaction because oxygen is added to ethanol (and hydrogen is removed) to form ethanoic acid.

   ½ mark

2. Oxidising agent: alkaline potassium permanganate (or acidified potassium dichromate).

   ½ mark

3. $\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{OH}\stackrel{\text{alkaline }\mathrm{KMn}{\mathrm{O}}_4+\text{heat}}{\to }\mathrm{C}{\mathrm{H}}_3\mathrm{COOH}$

   1 mark

4. Difference: this is a controlled oxidation in which ethanol changes into another organic compound, ethanoic acid. When ethanol burns in oxygen, it undergoes complete combustion to give carbon dioxide and water with a lot of heat and light: ${\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}+3{\mathrm{O}}_2\to 2C{\mathrm{O}}_2+3{\mathrm{H}}_2\mathrm{O}$ + heat + light.

   1 mark

Answer: Oxygen is added; oxidising agent is alkaline KMnO₄ or acidified K₂Cr₂O₇; $\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{OH}\to \mathrm{C}{\mathrm{H}}_3\mathrm{COOH}$; burning is complete combustion giving CO₂, H₂O, heat and light.

Revise the chapter

• Chapter: Carbon and its Compounds (notes, formulas, where marks are lost and every past question)