The test for unsaturated compounds
2 marks · EasyA sample of an alkene is tested with bromine water. The orange colour remains. Calculate the number of carbon–carbon double bonds present in one molecule of the alkene and explain your answer.
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Zero C=C double bonds present (±0)
Also accept: There are no carbon–carbon double bonds
Common mistakes: 1; 2
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Marking points
M1 · 1 mark · Recognises that if bromine water does not decolourise, there are no C=C bonds.
A1 · 1 mark · States number of double bonds is zero.
Worked solution
Bromine water only reacts and loses colour if there are C=C double bonds present. The orange colour remains, so there are zero carbon–carbon double bonds in one molecule.