17.2

Question 1

what are the 2 carbonyl compounds

Answer 1

aldehydes
ketones
(O=H)

Question 2

what makes a carbonyl compound an aldehyde

Answer 2

if there is a hydrogen joined to the carbonyl group (=O is on the end on a chain)

Question 3

what makes a carbonyl compound a ketone

Answer 3

if there are only hydrocarbon groups joined to the carbonyl group (=O is in the middle of the chain)

Question 4

explain the polarity of carbonyl groups

Answer 4

the bond is polar because of the different electronegativities of carbon & oxygen
electron density is greater near oxygen

Question 5

what are the physical properties of carbonyls and the difference between long & short chains

Answer 5

• distinctive smells
  long chain - pleasant smell
  short chain - unpleasant smell

Question 6

explain carbonyls boiling temperature

Answer 6

intermolecular forces of intermediate strength
contain polar C=O group so form permanent dipole dipole attractions but no hydrogen bonding

Question 7

what can’t most carbonyls not form hydrogen bonds

Answer 7

because all of their hydrogen atoms are joined to a carbon and therefor get in the way

Question 8

are carbonyls soluble in water

Answer 8

shorter chain carbonyls are soluble in water ass they can form hydrogen bonds but as they get longer the hydrocarbons become more significant & solubility decreases

Question 9

state the oxidation & reduction products for aldehydes & ketones

Answer 9

reduction:
aldehyde -> primary alcohol
ketone -> secondary alcohol

oxidation:
aldehyde -> carbonylic acid
ketone -> not easliy oxidized

Question 10

what reactant & conditions are needed for the reduction of carbonyls to alcohols

Answer 10

lithium aluminum hydride (lithium tertrahydridolaluminate)
LiAlH4
dissolved in dry ether

Question 11

how are aldehydes oxidized to carboxylic acids by acidified potassium dichromate (VI)

Answer 11

orange solution -> green solution
reduction of chromium from +6 to +3 causes colour change

Question 12

how are aldehydes oxidised to carboxylic acids by fehlings & benedicts solution

Answer 12

dark blue solution -> red precipitate
conversion of copper(II)
complex to copper (I) oxide

Question 13

how are aldehydes oxidised to carboxylic acids by tollens reagent (ammoniacal silver nitrate)

Answer 13

colourless solution -> silver mirror
conversion of silver(I) complex to metallic silver