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AP EAMCET · Chemistry · Alcohols Phenols and Ethers

Which reaction of ethanol will decolourise bromine water?

  1. A \(\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}+\mathrm{HBr} \longrightarrow \mathrm{C}_2 \mathrm{H}_5 \mathrm{Br}+\mathrm{H}_2 \mathrm{O}\)
  2. B \(2 \mathrm{C}_2 \mathrm{H}_5 \mathrm{OH} \xrightarrow[413 \mathrm{~K}]{\mathrm{H}^{+}} \mathrm{C}_2 \mathrm{H}_5-\mathrm{O}-\mathrm{C}_2 \mathrm{H}_5+\mathrm{H}_2 \mathrm{O}\)
  3. C \(\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}+\mathrm{Na} \longrightarrow \mathrm{C}_2 \mathrm{H}_5 \mathrm{ONa}+\frac{1}{2} \mathrm{H}_2 \mathrm{O}\)
  4. D \(\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH} \xrightarrow[443 \mathrm{~K}]{\mathrm{H}^{+}} \mathrm{C}_2 \mathrm{H}_4+\mathrm{H}_2 \mathrm{O}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH} \xrightarrow[443 \mathrm{~K}]{\mathrm{H}^{+}} \mathrm{C}_2 \mathrm{H}_4+\mathrm{H}_2 \mathrm{O}\)

Step-by-step Solution

Detailed explanation

One of the product in this reaction is ethene, an unsaturated hydrocarbon. It decolourises bromine water. Bromine solution is the classic test for the detection of unsaturation. A few drops of bromine water to the test tube with the ethanol produce reddish-brown colour.