CAIE A Level Chemistry 9701 · Chemical bonding
Ethene, , rapidly decolourises bromine water, whereas ethane, , does not react with bromine water under the same conditions. The carbon-carbon bond energy of ethene is 612 kJ mol⁻¹, but that of ethane is only 348 kJ mol⁻¹.
Suggest, in terms of the types of bond present and the orbital overlaps in the two molecules, why ethene is more reactive than ethane despite its higher carbon-carbon bond energy.
6 marks, so the mark scheme is looking for about 6 separate creditworthy points. Making the same point twice in different words earns it once.
Suggest means: Apply what you know to an unfamiliar situation. There may be more than one acceptable answer. Reason from the principle you have learned to the new context, and say which principle you are using.
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