2006 CE CHEM LQ # 1b) iii)

Acidified potassium permanganate solution can be used to distinguish between hex-1-ene and hexane.

Hex-1-ene can change acidified potassium permanganate solution from purple to colourless.
CH3CH2CH2CH2CH=CH2 + [O] + H2O → CH3CH2CH2CH2CH(OH)CH2(OH)

Hexane and acidified potassium permanganate give no observable change.