K.A-5 Oxidation Of Foods

Question 1

What is oxidation

Answer 1

Loss of hydrogen

Question 2

What is reduction

Answer 2

Gain of hydrogen

Question 3

What are the 4 main oxidising agents

Answer 3

Acidified potassium dichromate
Hot copper (II) oxide
Tollen’s reagent
Fehlings solution

Question 4

Uses and colour changes of acidified potassium dichromate

Answer 4

Oxidation of primary and secondary alcohols, and aldehydes

Orange to green

Question 5

Uses and colour change of hot copper (II) oxide

Answer 5

Oxidation of primary and secondary alcohols

Black to red

Question 6

Uses and colour changes of Tollens reagent

Answer 6

Oxidation of aldehydes not ketone

Formation of a silver mirror

Question 7

Uses and colour changes of Fehlings solution

Answer 7

Oxidation of aldehydes not ketones

Blue to brick red

Question 8

What is the reducing agent

Answer 8

CO

Question 9

What are the stages of primary alcohols being oxidised

Answer 9

Primary alcohols -> aldehydes -> carboxylic acid

Question 10

What are the stages of secondary alcohols being oxidised

Answer 10

Secondary alcohols -> ketone

Question 11

What attractions do aldehydes and ketones have

Answer 11

Due to the polar C=O functional group they contain Permanent Dipole-Permanent Dipole interactions

Question 12

Are aldehydes and ketones soluble in water

Answer 12

Yes as they are polar molecules and can form hydrogen bonds

Question 13

What happens when a aldehyde or ketone is reduced

Answer 13

They return back to there original primary or secondary alcohol

Question 14

In aldehydes where is the carboxyl group

Answer 14

At the end of a chain

Question 15

In ketone where is the carboxyl group found

Answer 15

In between two carbons

Question 16

What are antioxidants

Answer 16

Molecules that reduce the rate of oxidation reactions involving the transfer of electrons to an oxidising agent