Carboxylic acidsEdexcel A-Level Chemistry: Flashcards

What these 12 flashcards ask

What is the functional group of a carboxylic acid, and its suffix?
Why do carboxylic acids have high boiling temperatures?
Why are short-chain carboxylic acids soluble in water?
Why does solubility fall as the chain length of the acid increases?
How is a carboxylic acid made from a primary alcohol?
Why is reflux used when oxidising a primary alcohol to an acid?
How is a nitrile converted into a carboxylic acid?
What is the effect of the nitrile route on the carbon chain?
What does ethanoic acid give with sodium carbonate?
What does LiAlH₄ in dry ether do to a carboxylic acid?
What is formed when a carboxylic acid reacts with PCl₅?
What conditions form an ester from a carboxylic acid and alcohol?

Exam questions on Carboxylic acids

Ethanoic acid (relative molecular mass 60.0, boiling temperature 118 °C) has a much higher boiling temperature than propanal (relative molecular mass 58.0, boiling temperature 49 °C). Ethanoic acid mixes with water in all proportions, but hexanoic acid, CH₃(CH₂)₄COOH, is only slightly soluble.
Explain why ethanoic acid has a much higher boiling temperature than propanal.2 marks
A student plans to make propanoic acid in two different ways. One route starts from propan-1-ol. The other route starts from propanenitrile.
State the colour change seen when propan-1-ol is oxidised to propanoic acid by acidified potassium dichromate(VI), and explain why the mixture must be heated under reflux.2 marks
Ethanoic acid is used as a starting material in several reactions. In one test, aqueous sodium carbonate is added to ethanoic acid. In other reactions, ethanoic acid is converted into an acyl chloride by phosphorus(V) chloride and into an ester by reaction with ethanol.
Describe what is seen when aqueous sodium carbonate is added to ethanoic acid, and write the equation for the reaction.3 marks

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).