Physical properties

2 marks · Normal

State the general formula for alkenes. Write the molecular formula for the alkene with six carbon atoms.

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Also accept: CnH2n (general formula); C6H12 (molecular formula for 6 carbons); H2C=CH–CH2–CH2–CH2–CH3 as an example

Common mistakes: Giving general formula for alkanes (CnH2n+2); Incorrect molecular formula

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Marking points

B1 · 1 mark · State correct general formula: CnH2n

B2 · 1 mark · Correct molecular formula for 6 carbons: C6H12

Worked solution

The general formula for alkenes is CnH2n.

For an alkene with six carbon atoms, n=6, so the formula is C6H12.