AQA · GCSE · Chemistry
Course version: 8462 · Version from Sept 2018
Students should be able to recognise alcohols from their names or from…
Full specification wording
Alcohols: Students should be able to recognise alcohols from their names or from given formulae.
Alcohols are a homologous series of organic compounds containing the –OH functional group.
Checked against the AQA 8462 specification (opens in a new tab) on .
- Point 5 of 5
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Alcohols are a homologous series of organic compounds containing the –OH functional group. Their names end in -ol, so methanol, ethanol, propanol and butanol are alcohols. Their formulae show the –OH group attached to a carbon chain; for example, ethanol is C₂H₅OH and propanol is C₃H₇OH. Recognising an alcohol means identifying the –OH group in a displayed, structural or molecular formula, or using the -ol ending in a name. The general formula for alcohols with one –OH group is CₙH₂ₙ₊₁OH.
What earns the marks
- Identifies the –OH functional group in a displayed, structural or molecular formula.
- Uses the -ol ending in a name as evidence that the compound is an alcohol.
- Recognises ethanol as C₂H₅OH and propanol as C₃H₇OH.
- Distinguishes alcohols from alkanes, which contain only C–C and C–H bonds.
- Distinguishes alcohols from carboxylic acids, which contain the –COOH group.
- Applies the general formula CₙH₂ₙ₊₁OH to simple alcohols with one –OH group.
Common mistakes and how to put them right
Confusing the –OH group in an alcohol with the hydroxide ion, OH⁻.
Put it right: The alcohol functional group is a covalent –OH group, not a separate hydroxide ion.
Treating any compound containing oxygen as an alcohol.
Put it right: Look specifically for the –OH group attached to carbon, and note that carboxylic acids contain –COOH.
Mixing up the formulae of methanol and ethanol.
Put it right: Methanol is CH₃OH and ethanol is C₂H₅OH.
Exam tips
- Circle or underline the –OH group in a displayed formula before deciding whether the compound is an alcohol.
- Check the name ending: -ol indicates an alcohol, while -ane indicates an alkane and -oic acid indicates a carboxylic acid.
- When writing formulae, keep the –OH group intact rather than separating the oxygen and hydrogen.
Try the lesson
The start of the Alcohols: Students should be able to recognise alcohols from their names or from given formulae. lesson, made from checked teaching notes for this specification point.
Have a go first
Which of these names is an alcohol?
Listen
Alcohols are a homologous series of organic compounds containing the –OH functional group. Their names end in -ol, so methanol, ethanol, propanol and butanol are alcohols. Their formulae show the –OH group attached to a carbon chain; for example, ethanol is C₂H₅OH and propanol is C₃H₇OH. Recognising an alcohol means identifying the –OH group in a displayed, structural or molecular formula, or using the -ol ending in a name. The general formula for alcohols with one –OH group is CₙH₂ₙ₊₁OH. A strong answer earns marks for these points. Identifies the –OH functional group in a displayed, structural or molecular formula. Uses the -ol ending in a name as evidence that the compound is an alcohol. Recognises ethanol as C₂H₅OH and propanol as C₃H₇OH. Distinguishes alcohols from alkanes, which contain only C–C and C–H bonds. A common slip: Confusing the –OH group in an alcohol with the hydroxide ion, OH⁻. Instead, the alcohol functional group is a covalent –OH group, not a separate hydroxide ion. Exam tip: Circle or underline the –OH group in a displayed formula before deciding whether the compound is an alcohol.
Key words
Say what each word means before you turn the card.
Alcohols
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-ol ending
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–OH group
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Carboxylic acids
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See every definition
- Alcohols
- A homologous series of organic compounds containing the –OH functional group, whose names end in -ol.
- -ol ending
- Used in a name as evidence that the compound is an alcohol.
- –OH group
- The functional group identified in a displayed, structural or molecular formula to recognise an alcohol.
- Carboxylic acids
- Compounds that contain the –COOH group, from which alcohols are distinguished.
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