Learning focus
Develop accurate organic nomenclature, connect functional groups to reactions, draw structural and polymer formulae, interpret industrial processes and apply evidence to unfamiliar compounds.
Counting carbons
The carbon atom in -COOH is part of the parent chain. HCOOH has one carbon and is methanoic acid; CH3COOH has two and is ethanoic acid.
Required names
Methanoic, ethanoic, propanoic and butanoic acids correspond to one through four total carbon atoms. The suffix is -oic acid.
Structural formulae
The carboxyl group is written COOH at the end of a condensed formula. Propanoic acid is CH3CH2COOH and butanoic acid is CH3CH2CH2COOH.
Salt names
When a carboxylic acid reacts, the acid name changes from -oic acid to -oate in the salt. Ethanoic acid forms ethanoates, such as sodium ethanoate and magnesium ethanoate.
High-value recall and connections
Essential recall: Name CH3CH2COOH. Propanoic acid. What salt name comes from ethanoic acid? Ethanoate. Write the structural formula of butanoic acid. CH3CH2CH2COOH. Practical connection: Match acid structures to names and then name the salts formed with sodium, magnesium and calcium ions. Examination connection: Include the carboxyl carbon when counting the chain.
Practical or data skill
Match acid structures to names and then name the salts formed with sodium, magnesium and calcium ions.
Examination tip
Include the carboxyl carbon when counting the chain.
Review questions and suggested answers
Question 1
Name CH3CH2COOH.
Suggested answer
Propanoic acid.
Question 2
What salt name comes from ethanoic acid?
Suggested answer
Ethanoate.
Question 3
Write the structural formula of butanoic acid.
Suggested answer
CH3CH2CH2COOH.
