Module C2 - Material Choices

Question 1

What is water made from?

Answer 1

It is a chemical made up of water molecules. It is made up of hydrogen elements and oxygen elements.

Question 2

Name materials made from plants.

Answer 2

Wood and paper are made from trees. Cotton comes from the cotton plant.

Question 3

Name materials made from animals.

Answer 3

Wool comes from sheep. Silk is made from silkworm larva. Leather comes from cows.

Question 4

What is iron made from?

Answer 4

It is a chemical element made of iron atoms.

Question 5

What is the advantage of synthetic rubber over natural rubber?

Answer 5

It is easier to control its properties so it makes it suitable for lots of different purposes.

Question 6

What is stiffness?

Answer 6

A stiff material is good at not bending when a force is applied to it. Steel is very stiff as it is so hard to bend.

Question 7

What is strength?

Answer 7

Strength is how good a material is at resisting a force. It can be judged by how much force is needed to either permanently change its shape or break it.

Question 8

What is tensile strength?

Answer 8

How much a material can resist a pulling force. Cables and ropes must have a high tensile strength so they don’t snap.

Question 9

What is compressive strength?

Answer 9

How much a material can resist a pushing force. Bricks should have a high compressive strength so they are not squashed by bricks above.

Question 10

What is hardness?

Answer 10

How difficult it is to cut into. Diamond is the hardest material found in nature.

Question 11

What is density?

Answer 11

A material’s mass per unit volume. Air isn’t dense whereas gold is very dense. Objects that are less dense that water will float (ice). Objects that are more dense than water will sink.

Question 12

What are the properties of plastics?

Answer 12

Can be hard, strong and stiff. Fairly low density. Mouldable.

Question 13

What are the properties of rubber?

Answer 13

Strong yet soft and flexible. Mouldable.

Question 14

What are the properties of nylon fibres?

Answer 14

Soft, flexible and good tensile strength.

Question 15

What are hydrocarbons?

Answer 15

Molecules made of chains of carbon and hydrogen atoms.

Question 16

How does the length of the carbon Jains affect the boiling point?

Answer 16

Short chain molecules have lower boiling points and are often gases. Long chain molecules have high boiling points and can be viscous (thick and stick).

Question 17

Name the two bonds in crude oil.

Answer 17

Strong covenant bonds between the carbon and hydrogen atoms within each hydrocarbon molecule. The intermolecular forces of attraction between different hydrocarbon molecules in the mixture.

Question 18

Why do big molecules have higher boiling points?

Answer 18

Because they have higher forces of attraction therefore more energy is needed to break them out of a liquid to form a gas.

Question 19

What is the process of separating crude oil called? Briefly describe it.

Answer 19

It is called refining and it is done by fractional distillation. Hydrocarbons are separated into groups, called fractions, with different boiling points. The use of a hydrocarbon will depend on the length of its molecule chains.

Question 20

Name the useful products of crude oil, from those with the shortest chains to those with the longest chains.

Answer 20

Refinery gas. Petrol. Naphtha (a base for many chemicals). Kerosene (jet fuel). Diesel. Lubricating oil. Bitumen (used for road surfaces).

Question 21

What is chemical synthesis?

Answer 21

It is the process of making new compounds. This is done when useless hydrocarbons are split apart to make more useful hydrocarbons and ethene.

Question 22

How are polymers formed?

Answer 22

When monomers join together, under high pressure.

Question 23

If a polymer is strong and rigid, what can it be used to make?

Answer 23

Plastic milk bottles.

Question 24

To make PVC, what kind of properties are desirable?

Answer 24

Strong and durable. It can also either be rigid, to make window frames and piping, or stretchy, to make synthetic leather.

Question 25

Name a polymer and deceive how it has replaced natural materials.

Answer 25

Synthetic fibres, such as nylon and polyester, replace cotton, wool and silk. This is because it is more durable, lighter, water resistant and cheaper.

Question 26

How does the arrangement of the polymer chains affect the density?

Answer 26

If the polymer chains are packed close together, the material will have a high density. If the polymer chains are spread out, the material will have a low density.

Question 27

How is a polymer affected if it’s chains are held together by weak forces?

Answer 27

The chains are free to slide over each other which means the plastic can be stretched easily, and will have a lower melting point.

Question 28

How is a polymer affected if it’s chains are held together by strong forces?

Answer 28

It has a higher melting point and can’t be easily stretched. This is because of crosslinks, which are chemical bonds between the polymer chains, so the chains are held firmly together.

Question 29

How do cross linking agents affect a polymer?

Answer 29

The make the polymer stiffer, stronger and more heat resistant by chemically bonding the chains together.

Question 30

How do plasticisers affect a polymer?

Answer 30

They make the polymer softer and also easier to shape, by getting between the polymer chains and reducing the forces between them.

Question 31

If a polymer is made more crystalline, what does this mean?

Answer 31

Crystalline polymers have straight chains with no branches, so the chains fit closer together. They have higher density, are stronger and have a higher melting point.

Question 32

What is nanotechnology?

Answer 32

The branch of technology dealing with the making and use of nanoparticles.

Question 33

Name two ways in which nanoparticles can be made.

Answer 33

Seaspray - sea produces nanoscale salt particles which are present in the atmosphere. Combustion - when girls are burnt, nanoscale soot particles are produced.

Question 34

What do silver nanoparticles do?

Answer 34

They are added to polymer fibres used to make surgical masks and would dressings, to give them antibacterial properties.