U2-4-2 - Oxidation of Food

Question 1

Oxidation

Ratio, not electrons

Answer 1

Increase in O:H ratio

Adding O or removing H

Question 2

Reduction

Ratio, not electrons

Answer 2

Decrease in O:H ratio

Removing O or adding H

Question 3

Primary alcohols can be oxidised into…

Answer 3

aldehydes and carboxylic acids.

Question 4

Secondary alcohols can be oxidised into …

Answer 4

ketones.

Question 5

Which type of alcohols cannot be oxidised?

Answer 5

Tertiary

Cannot remove 2 Hs to form C=O bond

Question 6

Describe the colour change when hot copper(II) oxide is used to oxidise alcohols.

Answer 6

Black to brown

Question 7

Describe the colour change when acidified potassium dichromate is used to oxidise alcohols or aldehydes.

Answer 7

Orange to green

Question 8

Describe the colour change when Fehling’s solution is used to oxidise alcohols or aldehydes.

Answer 8

Blue (solution) to brick red (precipitate)

Benedict’s solution gives the same colour change

Question 9

Describe the change which is seen when** Tollens’ reagent** is used to oxidise a compound.

Answer 9

Silver mirror is formed