Alcohols, Carboxylic Acids and Polymers
Alcohols, carboxylic acids and polymers is the separate GCSE chemistry topic covering three further families of carbon compounds: alcohols, with the functional group -OH, carboxylic acids, with the functional group -COOH, and the two types of polymerisation, addition polymerisation from alkene monomers and condensation polymerisation, which forms synthetic polyesters and natural polymers such as proteins and DNA.
Before you start
Make sure you're comfortable with these topics first:
Method
- Identify the functional group in the molecule described, -OH for an alcohol or -COOH for a carboxylic acid, to decide which family of reactions applies.
- For an ethanol production question, decide whether fermentation or the reaction of ethene with steam is being described, and be ready to compare them on the renewability of the raw material, the rate of production, the purity of the product, and whether it is a batch or continuous process.
- For a carboxylic acid reaction question, recall the standard acid reactions (with a carbonate to give a salt, water and carbon dioxide) and describe carboxylic acids as weak acids that only partially ionise, rather than simply calling them 'weaker' with no explanation.
- To decide whether a polymerisation is addition or condensation, check whether the monomer is an unsaturated alkene forming a polymer with no by-product (addition), or has two functional groups with a small molecule such as water released each time a bond forms (condensation).
- When describing polymer formation, name the repeating unit that links to form the chain, and, for condensation polymerisation, state specifically which small molecule is released as the by-product.
- For 'compare fermentation and hydration' style questions, structure the answer as a series of direct contrasts (one point about each method side by side) rather than describing each process separately in full.
Worked example
Ethanoic acid reacts with propan-1-ol in the presence of a concentrated sulfuric acid catalyst. Name the organic product formed, and write a word equation for the reaction.
- Identify the type of reaction: a carboxylic acid (ethanoic acid) reacting with an alcohol (propan-1-ol) with an acid catalyst is esterification.
- Recall that esterification produces an ester plus water.
- Name the ester: combine the alcohol part (propyl, from propan-1-ol) with the acid part (ethanoate, from ethanoic acid) to give propyl ethanoate.
- Write the word equation: ethanoic acid + propan-1-ol -> propyl ethanoate + water.
- Final answer: the organic product is propyl ethanoate, formed alongside water.
Practice questions
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Q1State the functional group found in all alcohols.Show answer
Answer: -OH (the hydroxyl group).
Q2Name the two methods used to produce ethanol industrially.Show answer
Answer: Fermentation of sugar using yeast, and the catalytic reaction of ethene with steam.
Q3State the functional group found in all carboxylic acids.Show answer
Answer: -COOH (the carboxyl group).
Q4Name the carboxylic acid produced when ethanol is oxidised.Show answer
Answer: Ethanoic acid.
Q5Explain why carboxylic acids are described as 'weak acids'.Show answer
Answer: Because they only partially ionise (dissociate) in aqueous solution, rather than ionising completely, so they release fewer hydrogen ions than a strong acid of the same concentration.
Q6State what happens to the carbon-to-carbon double bond of an alkene monomer during addition polymerisation.Show answer
Answer: It opens up and becomes a single bond, allowing the monomer to bond directly to the monomers on either side of it in the chain.
Q7Name the small molecule typically released as a by-product during condensation polymerisation.Show answer
Answer: Water.
Q8Name the type of biological molecule formed when amino acid monomers join together by condensation polymerisation.Show answer
Answer: A protein (or polypeptide).
Exam-style questions
Written in the style of a GCSE Science exam paper, with a full mark scheme.
Ethanol can be produced either by fermentation of sugar or by reacting ethene with steam. Give two differences between these two production methods.
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Ethanoic acid reacts with solid calcium carbonate. Predict the three types of product formed, and describe one observation a student would make during this reaction.
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A dicarboxylic acid monomer and a diol monomer are reacted together to form a polyester. Explain, using ideas about bonding and functional groups, how condensation polymerisation forms this polymer, and explain how this process is different from the addition polymerisation of an alkene such as ethene.
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Free printable worksheet
Want more practice on paper? Download the alcohols, carboxylic acids and polymers worksheet pack - 16 pages of exam-style questions with a full mark scheme. One email opens every download in this browser for 14 days - no account, no card. Print it for personal and classroom use.
This topic is chapter 25 of GCSE Chemistry Workbook, the whole course as one free printable PDF.
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