Esters
Cambridge IGCSE Chemistry (0620) · Unit 11: Organic chemistry · 8 flashcards
Esters is topic 11.6 in the Cambridge IGCSE Chemistry (0620) syllabus , positioned in Unit 11 — Organic chemistry , alongside Formulae, functional groups and nomenclature, Alkanes and Alkenes. In one line: Fermentation requires aqueous glucose at 25–35 °C in the presence of yeast and in the absence of oxygen. Yeast provides enzymes to convert glucose into ethanol.
This topic is examined in Paper 1 (multiple-choice) and Papers 3/4 (theory), plus Paper 5 or Paper 6 (practical / alternative to practical). It is a Supplement (Extended-tier) topic, so it appears only on the Extended-tier papers.
The deck below contains 8 flashcards — 2 definitions and 6 key concepts — covering the precise wording mark schemes reward. Use the 2 definition cards to lock down command-word answers (define, state), then move on to the concept and application cards to handle explain, describe and compare questions.
Describe the conditions necessary for the fermentation of aqueous glucose to produce ethanol
Fermentation requires aqueous glucose at 25–35 °C in the presence of yeast and in the absence of oxygen. Yeast provides enzymes to convert glucose into ethanol.
What the Cambridge 0620 syllabus says
Official 2026-2028 specThese are the exact learning objectives Cambridge sets for this topic. Match the command word (Describe, Explain, State, etc.) in your answer to score full marks.
- Describe Describe the manufacture of ethanol by: (a) fermentation of aqueous glucose at 25– 35 °C in the presence of yeast and in the absence of oxygen (b) catalytic addition of steam to ethene at 300 °C and 6000kPa/60 atm in the presence of an acid catalyst
- Describe Describe the combustion of ethanol
- State State the uses of ethanol as: (a) a solvent (b) a fuel
- Describe Describe the advantages and disadvantages of the manufacture of ethanol by: (a) fermentation (b) catalytic addition of steam to ethene Supplement
Describe the conditions necessary for the fermentation of aqueous glucose to produce ethanol.
Fermentation requires aqueous glucose at 25–35 °C in the presence of yeast and in the absence of oxygen. Yeast provides enzymes to convert glucose into ethanol.
Outline the catalytic addition of steam to ethene for ethanol production, including conditions.
Ethene reacts with steam at 300 °C and 6000kPa (60 atm) in the presence of an acid catalyst (e.g., phosphoric acid). This produces ethanol.
Write the balanced chemical equation for the complete combustion of ethanol.
C₂H₅OH(l) + 3O₂(g) → 2CO₂(g) + 3H₂O(g). Complete combustion requires sufficient oxygen and produces carbon dioxide and water.
State two common uses of ethanol.
Ethanol is used as a solvent and as a fuel. As a solvent, it dissolves many organic compounds. As a fuel, it combusts readily to release energy.
What are the advantages of manufacturing ethanol by fermentation?
Fermentation uses renewable resources (glucose from plants). It can be done at lower temperatures and pressures compared to catalytic addition.
What are the disadvantages of manufacturing ethanol by fermentation?
Fermentation is a slow process. It produces a lower concentration of ethanol, requiring distillation. The process is also batch, not continuous.
What are the advantages of manufacturing ethanol by catalytic addition of steam to ethene?
Catalytic addition is a faster, continuous process. It produces a higher yield and concentration of ethanol compared to fermentation.
What are the disadvantages of manufacturing ethanol by catalytic addition of steam to ethene?
Catalytic addition requires high temperatures and pressures. Ethene is derived from non-renewable resources (crude oil).
Key Questions: Esters
Describe the conditions necessary for the fermentation of aqueous glucose to produce ethanol.
Fermentation requires aqueous glucose at 25–35 °C in the presence of yeast and in the absence of oxygen. Yeast provides enzymes to convert glucose into ethanol.
State two common uses of ethanol.
Ethanol is used as a solvent and as a fuel. As a solvent, it dissolves many organic compounds. As a fuel, it combusts readily to release energy.
Tips to avoid common mistakes in Esters
- ● Commit the definitions to memory
More topics in Unit 11 — Organic chemistry
Esters sits alongside these Chemistry decks in the same syllabus unit. Each uses the same spaced-repetition system, so progress in one informs the next.
Cambridge syllabus keywords to use in your answers
These are the official Cambridge 0620 terms tagged to this section. Mark schemes credit responses that use the exact term — weave them into your answers verbatim rather than paraphrasing.
Key terms covered in this Esters deck
Every term below is defined in the flashcards above. Use the list as a quick recall test before your exam — if you can't define one of these in your own words, flip back to that card.
Related Chemistry guides
Long-read articles that go beyond the deck — cover the whole subject's common mistakes, high-yield content and revision pacing.
How to study this Esters deck
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