The reagent used to distinguish an alkene from an alkane in the laboratory is
Correct answer: C. bromine water, which is decolourised by the alkene
- A. sodium metal
- B. silver nitrate solution
- C. bromine water, which is decolourised by the alkene
- D. limewater
Explanation
The orange colour of bromine water disappears as bromine adds across the double bond to form a colourless dibromo compound, and an alkane leaves the colour unchanged in the dark. Acidified potassium permanganate, which loses its purple colour, is the other standard test. Silver nitrate is used to test for halide ions and limewater for carbon dioxide.
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About Alkenes
Alkenes are unsaturated hydrocarbons containing a carbon-carbon double bond with sigma and pi components and restricted rotation. Their reactions include electrophilic addition of hydrogen, halogens, hydrogen halides and water, with Markovnikov orientation, oxidation, combustion and polymerisation, while their preparation commonly involves elimination from alkyl halides or alcohols.
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