Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
The test for unsaturated compounds
19 practice questions
Practice questions
11–19 of 19
Question 11
3 marks · Normal
Answer and see the solution →A student wants to test whether an unknown colourless liquid is an alkane or an alkene. The student adds a few drops of bromine water to the liquid in a test tube and shakes it. After a short time, the orange colour disappears and the mixture becomes colourless. Explain what conclusion the student should make about the liquid and the reason for this result.
Question 12
4 marks · Normal
Answer and see the solution →A student investigates the reaction between different alkenes and bromine water. The table shows the results.
Observations on addition of bromine water to different compounds. Compound Observation after adding bromine water Ethene Colourless Propene Colourless Butane Orange Cyclohexene Colourless (a)[2 marks]Which of these compounds are alkenes? Give a reason for your choice.
(b)[2 marks]Write a balanced equation for the reaction of ethene with bromine water.
Question 13
1 mark · Normal
Answer and check →Which observation confirms that a compound is an alkane, rather than an alkene, when tested with bromine water?
- A.The solution becomes colourless.
- B.The solution stays orange.
- C.A gas is given off.
- D.The solution turns milky.
Question 14
2 marks · Normal
Answer and see the solution →State the displayed formula of the product formed when but-1-ene reacts with bromine water, and give its name.
Question 15
4 marks · Normal
Answer and see the solution →(a)[1 mark]State what is meant by an unsaturated compound.
(b)[2 marks]Describe a chemical test to distinguish between hexane and hex-1-ene.
(c)[1 mark]Predict and state the result for each compound.
Question 16
3 marks · Normal
Answer and see the solution →When 28 g of ethene () gas reacts completely with bromine () solution in an addition reaction, calculate the maximum mass of 1,2-dibromoethane () that can be formed.
Give your answer to the nearest whole number. (Relative atomic masses: H = 1, C = 12, Br = 80)
Question 17
2 marks · Hard
Answer and see the solution →State and explain what you would observe when bromine water is added to but-2-ene. Write a chemical equation for the reaction.
Question 18
5 marks · Hard
Answer and see the solution →A student has two unlabelled liquid samples: cyclohexane and cyclohexene. The student wants to identify which is which using bromine water.
(a)[2 marks]Describe how the student should carry out the test with bromine water to distinguish between the two compounds.
(b)[2 marks]Predict and explain what you would observe with each compound after adding bromine water and shaking.
(c)[1 mark]Identify which compound is the alkene. Justify your answer based on your observations.
Question 19
2 marks · Hard
Answer and see the solution →Give the structural formula of the product formed when hex-2-ene reacts with bromine. Name the type of reaction that occurs.