Question detail

What is the expected product when propene reacts with hydrogen bromide?

Try the question, check the answer, then read the explanation to understand the curriculum point.

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At a glance

MCQ

Type

practice

Style

Topic

Alkenes

Question

A. Bromopropane
B. Propane
C. Bromobutane
D. Dibromopropane

Answer

Bromopropane

Explanation

When propene (an alkene) reacts with hydrogen bromide (HBr), the HBr adds across the double bond, resulting in the formation of bromopropane. This is an example of electrophilic addition where the hydrogen atom adds to one carbon and the bromine adds to the other.

Common mistake

Testing for Unsaturation with Bromine Water

Students often incorrectly state that bromine water changes color when it comes into contact with alkenes without mentioning the role of unsaturation.

To correctly explain the test for unsaturation, state the formula: Bromine water (Br2) reacts with unsaturated compounds (alkenes) to form colorless dibromo compounds. Substitution: When bromine water is added to an alkene, the C=C double bond reacts with Br2. Working: The reaction leads to the decolorization of bromine water, indicating the presence of unsaturation. Answer: The bromine water will turn from brown to colorless, confirming unsaturation. Units/Conclusion: The test confirms the presence of a C=C double bond in the alkene.

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