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Ethene, C₂H₄, is an unsaturated hydrocarbon - Edexcel - GCSE Chemistry - Question 7 - 2019 - Paper 1
Question 7
Ethene, C₂H₄, is an unsaturated hydrocarbon. (a) Explain why ethene is an unsaturated hydrocarbon. (b) A sample of ethene is burned completely in oxygen. Write the... show full transcript
Worked Solution & Example Answer:Ethene, C₂H₄, is an unsaturated hydrocarbon - Edexcel - GCSE Chemistry - Question 7 - 2019 - Paper 1
Step 1
Explain why ethene is an unsaturated hydrocarbon.
Answer
Ethene is classified as an unsaturated hydrocarbon because it contains carbon and hydrogen only, and it has at least one double bond between carbon atoms. This double bond means it has fewer hydrogen atoms than a saturated hydrocarbon with the same number of carbon atoms.
Step 2
Step 3
Describe what you would see when a sample of ethene and a sample of poly(ethene) are shaken with separate, small volumes of bromine water.
Answer
When bromine water is added to a sample of ethene, the solution will turn from brown to colorless due to a reaction with the double bond in ethene, which is a characteristic of unsaturated hydrocarbons. In contrast, when bromine water is added to poly(ethene), there will be no color change as poly(ethene) is saturated and does not react with bromine.