Alcohols
5 marks · EasyMethanol and ethanol are both alcohols used as fuels.
State the IUPAC name for the alcohol with molecular formula CH4O.
Explain how the –OH functional group in ethanol affects its chemical properties compared to alkanes.
Describe what happens in the combustion of ethanol, including the products formed.
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(a) methanol · must show correct IUPAC name
(b) — · must show Identifies that –OH makes ethanol an alcohol, States/Explains it allows combustion/oxidation and other reactions not possible with alkanes OR states it is more reactive due to –OH group
(c) — · must show States ethanol reacts with oxygen (burns in air), Identifies carbon dioxide and water are formed
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Marking points
B1 (a) · 1 mark · Gives correct IUPAC name (methanol).
B2 (b) · 1 mark · Mentions or explains effect of –OH group (e.g., makes it an alcohol or different from an alkane).
B3 (b) · 1 mark · States that –OH makes ethanol more reactive, allows it to undergo specific reactions (e.g., combustion, oxidation) not typical of alkanes.
B4 (c) · 1 mark · States ethanol burns/reacts with oxygen when combusted.
B5 (c) · 1 mark · Gives both main products: carbon dioxide and water.
Worked solution
a) The IUPAC name for CH4O is methanol.
b) The –OH group makes ethanol an alcohol, which is more reactive than alkanes. It allows ethanol to burn (combust) and be oxidized, giving ethanol properties not seen in similar alkanes.
c) When ethanol burns in air, it reacts with oxygen to produce carbon dioxide and water.