Fragrances/ Skin Care

Question 1

What are essential oils? (3 statements)

Answer 1

1. Organic products which are concentrated extracts from plants
2. They are volatile and non-water soluble
3. Used in perfumes, cosmetic and cleaning products and flavourings

Question 2

What are terpenes?

Answer 2

Unsaturated compounds formed by joining together isoprene units

Question 3

What is the common name for an isoprene?

Answer 3

2-methylbuta-1,3-diene

Question 4

How many carbons does one isoprene contain?

Answer 4

5

Question 5

How do you calculate the number of isoprene molecules in a structure?

Answer 5

Count the number of carbons and divide by 5

Question 6

What are terpenoids?

Answer 6

Terpenes containing oxygen or other functional groups

Question 7

What happens when terpenes are oxidised?

Answer 7

They produce compounds that are responsible for the aroma of spices

Question 8

What is Ultraviolet (UV) light?
(3 statements)

Answer 8

1. A high-energy form of light, present in sunlight
2. Can provide sufficient energy to break bonds within molecules. This causes sunburn and aging of the skin
3. Sun-block products prevent UV light reaching the skin

Question 9

What are free radicals?

Answer 9

Atoms or molecules that are highly reactive due to the presence of unpaired electrons

Question 10

How are free radicals formed?

Answer 10

When UV light break bonds

Question 11

Why do free radicals react quickly with other compounds?

Answer 11

Because they are unstable and react quickly to capture the needed electron to gain stability

Question 12

What do free radical scavengers do?

Answer 12

They react with free radicals to from stable molecules and prevent chain reactions

Question 13

What are free radicals scavengers added to?

Answer 13

Cosmetic products, food and plastics

Question 14

What are the 3 stages in a chain reaction?

Answer 14

Initiation, propagation and termination

Question 15

What is the initiation step in the chain reaction of
Cl2 + H2 –> 2HCl

Answer 15

The UV light breaks down some of the Cl-Cl bonds to form chlorine radicals:

Cl2(g) –> Cl(g) + Cl*(g)

Question 16

What is the propagation step in the chain reaction of
Cl2 + H2 –> 2HCl

Answer 16

Chlorine free radicals react with H2 molecules

H2(g) + Cl* –> H*(g) + HCl(g)

The product id called a hydrogen radical which react with chlorine molecules

Question 17

What is the termination step in the chain reaction of
Cl2 + H2 –> 2HCl

Question 18

What class of terpenes do molecules with 2 isoprene units belong to?

Answer 18

Monoterpene

Question 19

What class of terpenes do molecules with 3 isoprene units belong to?

Answer 19

Sesquiterpenes

Question 20

What class of terpenes do molecules with 4 isoprene units belong to?

Answer 20

Diterpenes