C2 - Material Choices

Question 1

Give one example of a chemical element

Answer 1

Iron

Question 2

Name a material we use that comes from plants

Answer 2

Wood and paper are both made from trees

Cotton comes from the cotton plant

Question 3

Name a material we use that comes from animal

Answer 3

Wool comes from sheep
Silk is made by the silkworm larva
Leather comes from cows

Question 4

Why do we use both natural and synthetic rubber?

Answer 4

Naturally it comes from the sap of the rubber tree so is cheaper to use from the sap of the tree
Synthetically rubber is made in a factory which means that you can control its properties, making it suitable for different purposes e.g. wetsuits

Question 5

Whats the difference between compressive and tensile strength?

Answer 5

Compressive strength is how much a material can resist a pushing force
Tensile (or tension) strength is how much a material can resist a pulling force

Question 6

What’s the hardest material found in nature?

Answer 6

Diamond

Question 7

Give a definition of density

Answer 7

Density is a material’s mass per unit volume (e.g. g/cm3)

Question 8

You’re measuring the properties of a material. Give three reasons why your results might not be accurate

Answer 8

• There might be a fault in your equipment
• Wrong results can because of human - inaccurate measuring, reading or recording of the results
• Your samples and techniques have to be the same every time

Question 9

Why should you always repeat your measurements?

Answer 9

It will allow for faults in the equipment, human error etc. It will then make your results more accurate.

Question 10

How can you ensure that an experiment is a fair test?

Answer 10

Vary only one factor in your experiment and to only measure one thing at a time. Each time you repeat the test the other factors must be exactly the same.

Question 11

Name two properties of plastic that make them useful in manufacturing

Answer 11

Can be fairly hard, strong and stiff
Some are fairly low density (good for lightweight goods)
Some are mouldable (easily made into things)

Question 12

Name two properties of rubber that make them useful in manufacturing

Answer 12

Strong but soft and flexible

Mouldable

Question 13

Name two properties of nylon that make them useful in manufacturing

Answer 13

Soft and flexible

Good tensile strength

Question 14

Name three properties that you’d look for when choosing a material to make a child’s dinner bowl

Answer 14

Non-toxic
Stiff
Non-brittle
Hard
Fairly high melting point

Question 15

What does crude oil contain?

Answer 15

A mixture of hydrocarbons, these chains are of varying lengths

Question 16

Briefly describe what happens during polymerisation

Answer 16

Under high pressure many small molecules ‘join hands’ (polymerise) to form long chains called polymers

Question 17

Give an example of a product where a polymer has replaced a natural material

Answer 17

Window frames used to be made from wood. Many new window frames are made from uPVC, a synthetic polymer.

Question 18

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

Answer 18

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 19

A polymer is easily stretched and has a low melting point. What can you say about the arrangement of its molecule chains and the forces holding them together?

Answer 19

Chains held together by weak forces are free to slide over each other

Question 20

What would you add to a polymer to make it stiffer and stronger?

Answer 20

Crosslinks hold the chains firmly together and will result in stronger forces so will make it stiffer and stronger. (Crosslinks are chemical bonds between the polymer chain)

Question 21

How do plasticisers work?

Answer 21

They can be added to a polymer to make it softer and easier to shape. Plasticisers work by getting in between the polymer chains and reducing the forces between them

Question 22

What are the properties of a crystalline polymer?

Answer 22

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

Question 23

Name the four main stages considered in a life cycle assessment

Answer 23

Extracting and refining raw materials
Manufacturing the product
Using the product
Disposing of the product

Question 24

Explain why a Life Cycle Assessment can’t tell you whether you should make a product or not

Answer 24

You have to consider other things when you’re making your decision:

• Making the product will benefit some people (like employers) and some products are essential to their customers (syringes for diabetics)
• Some people may be badly affected (e.g. land pollution)
• Many countries have laws which limit how much impact a company can have on the environment

Question 25

Give an example of a sustainable development

Answer 25

A paper company only using wood from forests that are replanted and regrow faster than the company is felling them, and taking steps to protect the wildlife that lives in the forests

Question 26

Why do we use both natural and synthetic rubber?

Answer 26

Cheaper to use naturally from the sap of the rubber tree
Synthetically rubber is made in a factory which means that you can control its properties, making it suitable for different purposes e.g. wetsuits

Question 27

What does crude oil contain?

Answer 27

Mixture of hydrocarbons, chains are of varying lengths

Question 28

What would you add to a polymer to make it stiffer and stronger?

Answer 28

Crosslinks. Holds the chains firmly together and will result in stronger forces so will make it stiffer and stronger. (Crosslinks are chemical bonds between the polymer chain)