Carboxylic acids
Cambridge IGCSE Chemistry (0620) · Unit 11: Organic chemistry · 12 flashcards
Carboxylic acids is topic 11.5 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: Alkenes contain a double carbon-carbon covalent bond. This double bond makes them unsaturated hydrocarbons.
This topic is examined in Paper 1 (multiple-choice) and Papers 3/4 (theory), plus Paper 5 or Paper 6 (practical / alternative to practical).
The deck below contains 12 flashcards — 2 definitions, 2 key concepts and 8 identification cards — 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.
What type of bond is present in alkenes
Alkenes contain a double carbon-carbon covalent bond. This double bond makes them unsaturated hydrocarbons.
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.
- State State that the bonding in alkenes includes a double carbon-carbon covalent bond and that alkenes are unsaturated hydrocarbons
- Describe Describe the manufacture of alkenes and hydrogen by the cracking of larger alkane molecules using a high temperature and a catalyst
- Describe Describe the reasons for the cracking of larger alkane molecules
- Describe Describe the test to distinguish between saturated and unsaturated hydrocarbons by their reaction with aqueous bromine
- State State that in an addition reaction only one product is formed Supplement
- Describe Describe the properties of alkenes in terms of addition reactions with: (a) bromine or aqueous bromine (b) hydrogen in the presence of a nickel catalyst (c) steam in the presence of an acid catalyst and draw the structural or displayed formulae of the products Supplement
What type of bond is present in alkenes?
Alkenes contain a double carbon-carbon covalent bond. This double bond makes them unsaturated hydrocarbons.
What is cracking and what conditions are required?
Cracking is the process of breaking down larger alkane molecules into smaller, more useful alkanes and alkenes. It requires a high temperature (heat) and a catalyst.
Why is cracking of larger alkane molecules important?
Cracking is important because it converts less useful, long-chain alkanes into smaller, more in-demand hydrocarbons like ethene (used to make plastics) and gasoline (fuel).
How can you distinguish between saturated and unsaturated hydrocarbons?
Unsaturated hydrocarbons (alkenes) react with aqueous bromine, decolourising it from brown to colourless. Saturated hydrocarbons (alkanes) do not react.
What type of reaction occurs when alkenes react?
Alkenes undergo addition reactions, where the double bond breaks and atoms add to each carbon atom. Only one product is formed.
What is the product of the addition of bromine to ethene?
The product is 1,2-dibromoethane. The bromine molecule adds across the double bond.
What is the product of the addition of hydrogen to ethene, and what conditions are required?
The product is ethane. This reaction requires a nickel catalyst and elevated temperature.
What is the product of the addition of steam to ethene, and what conditions are required?
The product is ethanol. This reaction requires an acid catalyst (
What is the product of cracking C₁₀H₂₂ into smaller alkanes and alkenes?
One possible set of products is: C₁₀H₂₂ → C₃H₈ + C₃H₆ + 2C₂H₄ (propane, propene, and ethene)
Give the name of the alcohol produced when propene reacts with steam.
The alcohol produced is propan-2-ol (also known as isopropyl alcohol).
What is the name of the salt produced when propanoic acid reacts with sodium hydroxide?
The salt produced is sodium propanoate.
What is the catalyst used for the addition of steam to alkenes?
Concentrated sulfuric acid (H₂SO₄) is used as the acid catalyst.
Key Questions: Carboxylic acids
What type of bond is present in alkenes?
Alkenes contain a double carbon-carbon covalent bond. This double bond makes them unsaturated hydrocarbons.
What type of reaction occurs when alkenes react?
Alkenes undergo addition reactions, where the double bond breaks and atoms add to each carbon atom. Only one product is formed.
Tips to avoid common mistakes in Carboxylic acids
- ● Burn into your brain the key differences between diamond and graphite: hardness AND electrical conductivity.
- ● Solidify the gaseous products: metal carbonates → CO2, and metal nitrates → NO2 + O2.
- ● When explaining carbon monoxide's danger, stick to the key fact: it's poisonous.
- ● Drill the precise general formulae like CnH2n+1COOH (or RCOOH) — these must be written accurately.
- ● When studying acids, note that ethanoic acid will neutralize alkaline solutions, react with metals to form hydrogen gas, and react with carbonates to form CO2.
More topics in Unit 11 — Organic chemistry
Carboxylic acids 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 Carboxylic acids 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
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