unit 2 KA6 - oxidation of food Flashcards
what is oxidation
the increase in the oxygen to hydrogen ratio
what is reduction
the decrease in the oxygen to hydrogen ratio
what substances are used to oxidise primary alcohols to aldehydes and then to carboxylic acids and secondary alcohols to ketons?
hot copper (II) oxide or acidified dichromate (VI) solutions
what can hot copper (II) oxide or acidified dichromate (VI) solutions be used to oxidise
primary alcohols to aldehydes and then to carboxylic acids, and secondary alcohols to ketones
can tertiary alcohols be oxidised with hot copper (II) oxide or acidified dichromate (VI) solutions
no
what colour does orange dichromate solution turn during an oxidation reaction
green lol
what does black copper (II) oxide form in these oxidation reactions
a brown solid hehe
what is the functional group found in aldehydes and ketones
the carbonyl functional group –C=O
how can straight chain and branched aldehydes and ketones be named
they can be systematically named from structural formulae containing no more than eight carbons in the long chain?
what are the differences between aldehydes and ketones
- aldehydes can be oxidised to carboxylic acids, but ketones cannot
- their chemical structure - in aldehydes, C=O is attached to a H and an R. in ketones, C=O is attached to 2 R
what happens when you oxidise an aldehyde
- blue fehling’s solution forms a brick red precipitate
- clear, colourless tollens reagent forms a silver mirror
- orange acidified dichromate solution turns green
use of aldehydes?
many flavour and aroma molecules are aldehydes
is it true that the oxygen from the air causes oxidation of food, and that the oxidation of edible oils gives food a rancid flavour?
yes
what is an example of oxidation of food
apples going brown
what are antioxidants
molecules that prevent unwanted oxidation reactions occurring
