Ethanol burns in air
2 marks · HardExplain why water is always formed as a product when any alcohol burns completely in air.
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Also accept: Alcohols contain hydrogen and oxygen atoms, so when they react with oxygen (burn), the hydrogen combines with oxygen to make water.; All alcohols contain hydrogen, which forms water when it reacts with oxygen in the air during combustion.
Common mistakes: Saying water forms because air contains water; Ignoring the hydrogen atoms in the alcohol
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Marking points
M1 · 1 mark · Mentions alcohols contain hydrogen (and/or oxygen) atoms
M2 · 1 mark · Correctly explains hydrogen atoms react with oxygen to form water
Worked solution
All alcohols contain hydrogen atoms in their molecules. During complete combustion in air, the hydrogen in alcohol reacts with oxygen to form water.