Ethanal - test for aldehydes Flashcards Preview

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Flashcards in Ethanal - test for aldehydes Deck (6):
1

Describe a chemical test to confirm that ethanal can be easily oxidised

-Add fehlings solution and heat gently
Blue cu2+ react and is reduced and forms a red precipitate
-Add Tollen’s solution which contains colourless At+
It reacts and is reduced and forms a silver mirror precipitate

2

Suggest a weak oxidising reagent that could be used to distinguish between an aldehyde and a ketone

Fehlings reagent

3

Why does propanone not react with Fehlings reagent

Propanone is not easily oxidised

4

Describe the colour change observed when acidified potassium permanganate solution is added to ethanal and name the organic product formed

Purple colour of potassium permanganate changes to colourless
Organic product - ethanoic acid

5

Describe the colour change observed when Fehlings solution is added to ethanal and name the organic product formed

Blue colour of solution disappears and red precipitate is formed.
Organic product - ethanoic acid

6

What would you expect to observe when Fehlings reagent is added to some propanone in a test-tube? Explain your answer

No change observed since Fehling's reagent does not oxidise ketones