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C2H4
Two carbons and four hydrogens.
O Level · English Medium · Cambridge · Chemistry
Organic chemistry and practical investigation
Connect organic functional groups, reaction evidence and an investigation plan.
Shared cross-level core and stretch unit. Start with the core questions, then use the stretch example for deeper work. The same unit is available in related class and board pathways; it is not a full grade-specific or examination-specification course. A teacher should select the appropriate depth and further topics.
Learn the idea
A functional group helps determine an organic compound’s characteristic reactions. An alkane has only carbon-carbon single bonds; an alkene contains a carbon-carbon double bond. An alcohol has a hydroxyl group attached to a carbon in the alcohol context. Formula, structure and conditions all matter.
Worked example
Ethene is C2H4 and ethanol C2H5OH. Addition of water across ethene’s double bond can form ethanol under suitable industrial conditions. This is a reaction description, not a home experiment.
- Draw a structural formula.
- Identify the reacting group and conditions.
- Use evidence and controls in a proposed test.
Stretch example
In a simple nucleophilic substitution, OH− can replace a halide group in a suitable haloalkane. Reaction pathway and rate depend on structure, solvent and conditions; a reaction name alone is not a complete prediction.
Your written practice
Show your working on paper and enter your answer here. If it does not match, compare the model and try again.
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alcohol
Ethanol contains the alcohol hydroxyl group.
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addition
The double bonds open to join monomers without a small molecule being eliminated.
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Structural isomers can have the same molecular formula but different connectivity.
Mention a difference in arrangement.
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The control helps show whether the observed change is due to the substance rather than the reagent or procedure alone.
Describe the comparison’s purpose.
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ethanol
The two-carbon skeleton remains while the functional group changes.
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Addition joins groups across a multiple bond; substitution replaces one atom or group with another.
Describe the structural change in each.
Organic reaction map
Draw a paper map linking ethene, ethanol and ethanoic acid.
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- Show structural formulae.
- Name each type of change.
- Mark that practical conditions require supervised laboratory work.
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