Which of the following compounds is most likely to decolorize bromine water at room temperature?
Show the answer and explanation
Correct answer
B. Ethene
Principle or equation
Alkenes contain a carbon-carbon double bond, which undergoes addition reactions with bromine, decolorizing bromine water. Alkanes, alcohols, and carboxylic acids do not react readily with bromine under these conditions.
Why this answer is correct
Ethene (C2H4) has a double bond and will add bromine across it, forming 1,2-dibromoethane and decolorizing the orange bromine water. Ethane is saturated and unreactive; ethanol and ethanoic acid do not react with bromine water at room temperature.
Example
Bubbling ethene through bromine water turns it from orange to colorless, whereas ethane does not change the color.
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