Question

When an alkene is mixed with bromine water:

• A. The bromine water changes from orange to colourless
• B. The bromine water stays orange
• C. The bromine water changes from colourless to orange
• D. The bromine water change from brown to colourless

Answer 1

The correct option is D The bromine water change from brown to colourless

This is a confirmatory test of alkenes. When an alkene is mixed with bromine water its colour changes from brown to colorless. Bromine water is a brown coloured liquid . When bromine react with alkene it forme dibromo alkene by addition reaction, due to which brown colour disappears.

Example: $R-C{H}_2=C{H}_2-R+B{r}_2\to R-C{H}_{2}Br-C{H}_{2}Br-R$