aldehydes and ketones

Question 1

Write an overall equation for the reduction of butanone using [H] to represent the reductant

Answer 1

CH3CH2COCH3 + 2[H] –> CH3CH2CH(OH)CH3

Question 2

Give a suitable reagent and state the necessary conditions for the conversion of propan-2-ol into propanone. Name the type of reaction.

Answer 2

potassium dichromate (VII)

acidified/ catalyst H2SO4

oxidation or redox

Question 3

Propanone can be coverted back into propan-2-ol. Give a suitable reagent and write an equation for this reaction

Answer 3

NaBH4

CH3COCH3 + 2[H] –> CH3CH(OH)CH3

Question 4

functional group of aldehydes

Answer 4

CHO

Question 5

functional group of ketones

Answer 5

C=O

Question 6

Suggest reagent and observations for a test to distinguish propanone and propanal

Answer 6

Tollen’s reagent
one- stays colourless
al- silver mirror

Fehling’s solution
one- stays blue (NO REACTION)
al- brown precipitate

acidified potassium dichromate VII
one- stays orange
al- turns green

Question 7

suggest one reason why Tollen’s reagent is used as the oxidising agent in the specific test for aldehydes rather than the less expensive acidified potassium dichromate VII

Answer 7

Dichromate VII will also oxidise