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The diagram shows the structure of a molecule of ethene - Edexcel - GCSE Chemistry - Question 2 - 2012 - Paper 1
Question 2
The diagram shows the structure of a molecule of ethene. Ethene is unsaturated. Ethene is a hydrocarbon. Explain why ethene is described as an unsaturated hydrocar... show full transcript
Worked Solution & Example Answer:The diagram shows the structure of a molecule of ethene - Edexcel - GCSE Chemistry - Question 2 - 2012 - Paper 1
Step 1
Explain why ethene is described as an unsaturated hydrocarbon.
Answer
Ethene is described as an unsaturated hydrocarbon because it contains a double bond between two carbon atoms. In its molecular structure, this double bond represents a point of unsaturation where hydrogen atoms could be added. Saturated hydrocarbons, in contrast, contain only single bonds between carbon atoms and are fully 'saturated' with hydrogen. Therefore, the presence of the double bond in ethene indicates that it can undergo addition reactions, which is a characteristic of unsaturated hydrocarbons.
Step 2
Describe what you would see when a sample of ethene is shaken with bromine water.
Answer
When a sample of ethene is shaken with bromine water, the solution would change color from orange-brown to colorless. This color change occurs because the bromine adds across the double bond in ethene, effectively removing the bromine from the solution and indicating a chemical reaction has taken place.