Unit 2: Skincare

Question 1

How are free radicals formed

Answer 1

When uv light breaks bonds

Question 2

What are the free radical chain reactions

Answer 2

1. Initiation
2. Propagation
3. Termination

Question 3

Initiation

Answer 3

UV light provides energy provided to break Cl-Cl bond to split some of the chlorine molecules into free radicals, Cl free radicals are extremely unstable and highly reactive.

Question 4

Propagation

Answer 4

Free radicals collide with other species, but the numbers of free radicals is maintained. Product of this reaction is known as a hydrogen radical.

Question 5

Termination

Answer 5

Free radicals are used up by collisions with each other. Another free radical is substituted into an alkane in the presence of UV. This presence is not explosive and results in the decolourisation of bromine.

Question 6

Free radical scavengers

Answer 6

Molecukes which can react with free radicals to form stable molecules and prevent chain reactions
Melatonin and vitamins C and E are examples.

Question 7

Link to oxidation of foods

Answer 7

Oxidation reactions that happen when food spoils, also involve the production of free radicals, this explains why free radical scavengers such as vitamin C and E are added to food products.
Therefore antioxidants are free radical scavengers.