skincare

Question 1

What does sunlight contain?

Answer 1

UV light, a very high energy light capable of breaking chemical bonds.

Question 2

What is the effect of UV light on skin?

Answer 2

exposing skin to UV light helps product vitamin D but can also cause skin to age and too much causes sunburn.

Question 3

What do sunscreens do?

Answer 3

contain compounds that filter the amount of UV light reaching our skin.

Question 4

What do sunblocks do?

Answer 4

contain compounds that reflect UV light so it does not reach the skin at all.

Question 5

What are free radicals?

Answer 5

They are highly reactive atoms or molecules with unpaired electrons.

Question 6

How are free radicals formed?

Answer 6

UV light has enough energy to break covalent bonds to form free radicals.

Question 7

Name and describe the first stage of free radical reactions… (e.g. of methane and chlorine)

Answer 7

Initiation: UV light is shone onto methane/chlorine mixture, breaks Cl atoms to form Cl free radicals.

Question 8

Name and describe the second stage of free radical reactions… (e.g. of methane and chlorine)

Answer 8

Propagation: chlorine radicals react with methane to produce methyl radicals which then react with chlorine molecules.

Question 9

Name and describe the final stage of free radical reactions… (e.g. of methane and chlorine)

Answer 9

Termination: two free radicals form stable molecules, end up with chlorine, ethane and chloromethane.

Question 10

What are free radical scavengers?

Answer 10

compounds that combine with radicals to form stable molecules

Question 11

Why are free radical scavengers useful?

Answer 11

they stop free radical chain reactions that cause wrinkles; e.g. Vitamins C and E; also added to food and plastics to prevent spoiling or damage (antioxidants)