Learning focus
Develop accurate organic nomenclature, connect functional groups to reactions, draw structural and polymer formulae, interpret industrial processes and apply evidence to unfamiliar compounds.
Oxidation equation
Ethanol can be oxidised to ethanoic acid: CH3CH2OH + 2[O] -> CH3COOH + H2O. The [O] symbol represents oxygen supplied by an oxidising agent.
Oxidising agent and observation
Acidified aqueous potassium manganate(VII) is purple and is decolourised as it oxidises ethanol. Heating under suitable controlled conditions speeds the reaction.
Structural change
The terminal CH2OH part becomes COOH. Carbon gains bonding to oxygen and loses bonding to hydrogen, consistent with oxidation.
Experimental distinction
If ethanol is merely burned, complete combustion gives CO2 and H2O. Controlled oxidation preserves the two-carbon skeleton and produces ethanoic acid.
High-value recall and connections
Essential recall: Name the oxidising agent. Acidified aqueous potassium manganate(VII). What colour change occurs? Purple to colourless. Write the organic product. CH3COOH. Practical connection: Interpret colour-change observations for acidified potassium manganate(VII) and write the organic structural change. Examination connection: Do not confuse controlled oxidation to ethanoic acid with complete combustion.
Practical or data skill
Interpret colour-change observations for acidified potassium manganate(VII) and write the organic structural change.
Examination tip
Do not confuse controlled oxidation to ethanoic acid with complete combustion.
Review questions and suggested answers
Question 1
Name the oxidising agent.
Suggested answer
Acidified aqueous potassium manganate(VII).
Question 2
What colour change occurs?
Suggested answer
Purple to colourless.
Question 3
Write the organic product.
Suggested answer
CH3COOH.
