Bromine Water Test for Alkenes Flashcards

1️⃣ Familiarise yourself with the flashcards:

  • Look through all the flashcards to see what's on both sides.
  • Make sure you understand the information on each card. If something's unclear, click the link to the revision notes at the bottom of the page for more details.

2️⃣ Test yourself:

  • Look at the question or prompt on each card and try to remember the answer before flipping it over.
  • Check the answer and make a note of any cards you find challenging and need to go over more.

3️⃣ Consistently Review and Practice:

  • Use spaced repetition: spend more time on the cards you struggle with and go over them more often.
  • Regularly review all the flashcards to help you better understand and retain the information over time.

Note: We may include questions that have multiple correct answers. It's useful to remember specific examples to understand these concepts better.

PERSONALISED 1-TO-1 TUTORING

Need more help on this topic? Get 1-to-1 support

Get support with clear explanations, practice and feedback (Ages 5 to 16).

  • DBS-checked tutors
  • Flexible times
  • Parents can be updated

Want an ad-free experience? Subscribe to remove ads

What is bromine water?

Bromine water is a dilute solution of bromine in water. It is used as a chemical test.

What colour is bromine water before it is added to a hydrocarbon?

Bromine water is orange before it is added to a hydrocarbon.

What does the bromine water test look for in a molecule?

The bromine water test looks for a carbon–carbon double bond, which shows the molecule is an alkene.

What happens to bromine water when it is added to an alkene and shaken?

When bromine water is added to an alkene and shaken, it changes from orange to colourless.

What happens to bromine water when it is added to an alkane in normal light?

When bromine water is added to an alkane, it stays orange and does not change colour in normal light.

What does it tell you if bromine water goes colourless when tested with a hydrocarbon?

If bromine water goes colourless, the hydrocarbon is unsaturated, so it is an alkene.

What does it tell you if bromine water stays orange when tested with a hydrocarbon?

If bromine water stays orange, the hydrocarbon is saturated, so it is most likely an alkane.

Why do alkenes decolourise bromine water but alkanes do not?

Alkenes react with bromine across the carbon–carbon double bond in an addition reaction. Alkanes do not react under these conditions.

Give a word equation for the reaction between ethene and bromine in the bromine water test.

Ethene + bromine → dibromoethane.

How do you carry out a bromine water test on a liquid hydrocarbon sample?

Add a few drops of bromine water to the sample, shake the test tube gently, and watch to see if the orange colour goes colourless.