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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 classified as an unsaturated hydrocarbon because it contains at least one carbon-carbon double bond (C=C). This double bond means that not all carbon atoms are bonded to the maximum number of hydrogen atoms, resulting in fewer hydrogen atoms overall compared to saturated hydrocarbons like alkanes, which contain only single bonds and are fully saturated with hydrogen. The presence of this double bond is what defines ethene as unsaturated.
Step 2
Describe what you would see when a sample of ethene is shaken with bromine water.
Answer
When ethene is shaken with bromine water, the solution will change from a reddish-brown color to colorless. This color change occurs because ethene reacts with bromine, resulting in the formation of a dibromoethane compound, effectively decolorizing the bromine water.