Question

Acetylene and benzene are distinguished by which reagent

Answer 1

Benzene does not decolourise pink colour of alkaline KMnO4, which is a test for unsaturation, but acetylene does decolourise alkaline KMnO4, that is benzene gives negative Bayer's test but Acetylene gives positive Bayer's test.

Answer 2

The correct answer for the question is Tollens reagent.

• Acetylene and Benzene can be distinguished by Tollens reagent in the laboratory.
• Tollens reagent is a chemical reagent used to determine the presence of aldehyde, aromatic aldehyde, and alpha hydroxy ketone functional groups.
• The reagent consists of a solution of ammonia and silver nitrate.
• Fehling's solution is a deep blue alkaline solution that is used to identify the presence of aldehydes, groups that contain an aldehyde functional group, or a ketone.
• Fehling's A contains Blue copper sulfate.
• Fehling's B is a clear liquid containing potassium sodium tartrate and a strong alkali.
• Bromine water (or Bromide bromate solution: It is used to identify the alkene or alkane functional groups present in the compound. Alkene groups react with Bromine water in the dark and undergo an addition reaction to give a decolorized solution. Alkane doesn't react with Bromine water and the color of the Bromine water remains the same.
• Potassium Permanganate is a strong oxidizing agent and is purple in color: It is used for medication for dermatitis, for cleaning wounds, and for general disinfection.
• Key points: The main difference between Acetylene and benzene is that benzene is a ring while acetylene is an alkyne.

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