Materials

Question 1

Explain the structure of soap/detergent

Answer 1

• Head = hydrophilic, contains oxygen atoms and is polar. = mix with water
• Tail = hydrophobic, contains carbon and hydrogen and is non- polar = mix with oil

Question 2

Explain the term emulsifying agent

Answer 2

a substance that is both soluble in water and oil

Question 3

Explain how the structure of soap/detergent allows it to act as an emulsifying agent

Answer 3

The soap molecules makes the oil droplet soluble in the water by arranging the tail to mix with oil and the head to mix with water.
• This action also lowers the surface tension of water and makes the oil more soluble in the water.

Question 4

Name the advantages of soap and detergents

Answer 4

1. Can clean fat and oil from dishes and clothes.

2. Prevents the formation of scum when hard water is used.

Question 5

Name the disadvantages of soap and detergents

Answer 5

1. Non–biodegradable detergents can cause water pollution.

Question 6

What is the impact of soap and detergents on the environment?

Answer 6

• Soap made from animal fats and or vegetable oils is bio – degradable.
• Detergents that are made from oil or coal is non – biodegradable.

Question 7

What is the difference between emulsifying agent, emulsion and emulsifier?

Answer 7

Emulsifying agent: a substance that is soluble in water and in fat, enables the fat to be dispersed in the water.
Emulsion: a mixture of two liquids that are not usually able to mix.
Emulsifier: a substance that stabilizes an emulsion.

Question 8

What is nanotechnology?

Answer 8

It is the production of nanomaterials

Question 9

What is nanomaterials?

Answer 9

Materials in which the particle size range between 1 and 100 nm in one dimension.
(1nm = 1 x 10 -9m)

Question 10

What properties does the small size of nanomaterials give them?

Answer 10

This small size gives the materials other properties like
• better electrical conductors,
 • lighter,
• stronger
• more durable

Question 11

What are the applications of nanotechnology?

Answer 11

1. medicine
2. electronics
3. environmental health
4. consumer products
5. sporting goods

Question 12

How concrete is made?

Answer 12

• Mix sand, gravel, cement and water
• When adding water, crystals start to form
• Crystals interlock
• Strong crystals form when concrete is allowed to dry slowly
• Thus concrete is wet for several days after it has been made

Question 13

Name the properties and uses of concrete

Answer 13

High compressive and tensile strength

Bricks
Foundations
Walls