Ethanol reacts with oxygen in two different ways depending on the conditions. Describe what happens when ethanol undergoes incomplete combustion, and state two other uses of ethanol that are not related to combustion.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Incomplete combustion of ethanol:
1. –C2H5OH + 1.5O2 → CO + 2H2O
2. Often also gives soot (C) and smoke.
Other uses of ethanol (not combustion):
1. Alcoholic beverages.
2. Solvent in perfumes and cleaning products.
1. –C2H5OH + 1.5O2 → CO + 2H2O
2. Often also gives soot (C) and smoke.
Other uses of ethanol (not combustion):
1. Alcoholic beverages.
2. Solvent in perfumes and cleaning products.
Examiner tips
- Use the exact reaction equation for incomplete combustion; mention CO and water. State soot as a possible product. Give two distinct non‑combustion uses, e.g. drinks and solvent.
Mark scheme (4 marks)
- Incomplete combustion of ethanol produces carbon monoxide (and water)
- Carbon (soot/smoke) may also be produced during incomplete combustion
- First valid use of ethanol unrelated to combustion — alcoholic drinks / solvent / in perfumes / cleaning agent / antiseptic
- Second valid use of ethanol unrelated to combustion — different from first answer
Key terms in this question
incomplete combustion · ethanol
Related
- All Cambridge International IGCSE Chemistry (0620) revision notes →
- How to answer a "Describe" question →
- Decode the mark scheme abbreviations →
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