Chemical reactions of the alkenes
2 marks · HardGive a general description of what happens to an alkene during a combustion reaction. Explain why alkenes are not normally used as fuels.
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Also accept: Description of combustion (burn to form CO2 and H2O) and comment on alkenes being more useful for other reactions
Common mistakes: Suggesting incomplete combustion only; Saying alkenes are not reactive
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Marking points
B1 · 1 mark · States that alkenes burn/undergo combustion to produce carbon dioxide and water.
B2 · 1 mark · Explains that alkenes are not usually used as fuels because they are more useful in other chemical reactions (e.g., addition reactions/producing useful compounds).
Worked solution
When an alkene burns in oxygen, it reacts to form carbon dioxide and water. Alkenes are not normally used as fuels because they are more useful for making other chemicals in addition reactions than for burning as fuels.