QUESTION 24 (4 marks)
Citronellol is a common ingredient used in the fragrance industry and a component of citronella oil, an insect repellant. Its structure is shown.
CH3 CH3
CH3 CH3
CH3 CH3
CH2 CH2 CH2 CH2
CH2 CH2 CH2 CH2
C CH CH
CH CH
OH OH
a) Classify citronellol as saturated or unsaturated. Explain your reasoning.
[2 marks]
b) Describe a chemical test that could be used to confirm whether citronellol is saturated or unsaturated.
[2 marks]
QCAA guide · typeset solution
QCAA sample response and mark allocation
24a) | Unsaturated because it contains a double bond | • classifies citronellol as unsaturated [1 mark] • explains that it contains a double bond [1 mark] |
24b) | Bromine water could be used to confirm that citronellol is unsaturated. When added to citronellol, bromine water will change from brown/orange to colourless because the molecule is unsaturated. | • identifies a suitable chemical test [1 mark] • describes a suitable chemical test [1 mark] |
QCAA sample response and marking criteria reproduced from the official guide.
Compare your working with the guide above.