Material Choices

Question 1

What makes a material suitable for a job?

Answer 1

The properties that it has

Question 2

Name some properties that might be important for the job a material is being used for.

Answer 2

Melting point, tensile strength, compressive strength, stiffness, hardness, density

Question 3

What is the melting point of a material?

Answer 3

The temperature at which it turns into a liquid.

Question 4

What is tensile strength?

Answer 4

The force needed to break a material when it is being stretched

Question 5

What is compressive strength?

Answer 5

The force needed to crush a material

Question 6

What is stiffness?

Answer 6

The force needed to bend a material

Question 7

What is hardness?

Answer 7

How well a material stands up to wear

Question 8

What is density?

Answer 8

The mass of a given volume of the material, so it is a measure of how heavy the material is.

Question 9

How can you influence the properties of a given material?

Answer 9

Changing the size and shape can have an impact, eg glass can be spun into glass fibres.

Question 10

How are ropes made?

Answer 10

By winding fibres together, the more fibres the stronger the rope.

Question 11

What does crude oil consist of?

Answer 11

It is a mixture of thousands of hydrocarbons, with chains up to 100 carbon atoms long.

Question 12

What are hydrocarbons mainly used for?

Answer 12

Fuel

Question 13

How does the number of each type of atom change during a chemical reaction.

Answer 13

It doesn’t.

Question 14

Is the composition of crude oil constant?

Answer 14

No.

Question 15

How are the various fractions of crude oil separated?

Answer 15

Fractional distillation.

Question 16

What is the relationship between boiling point, and length of carbon chain, in hydrocarbons?

Answer 16

The longer the carbon chain the more energy is required to break out of the liquid, so the boiling point is higher.

Question 17

How would you make a polymer?

Answer 17

You join many smaller molecules called monomers

Question 18

How many carbons in a polymer?

Answer 18

From hundreds to millions.

Question 19

What is the process for making a polymer?

Answer 19

Polymerisation.

Question 20

Name a monomer and the polymer made from it.

Answer 20

Ethene make polyethene.

Question 21

Molecules are weakly attracted to each other, this force increases as they come closer. If molecules “fit” nicely, would this increase or decrease the melting point?

Answer 21

Increase.

Question 22

What is the effect of branching polymer chains on the melting point?

Answer 22

The branches hold the molecules apart, reducing the attraction force between the molecules, so the melting point will go down.

Question 23

What is the effect of branched polymer chains on the strength/flexibility of the material?

Answer 23

The branches hold the molecules apart, reducing the attraction force between the molecules, so the material will be soft, flexible, weak.

Question 24

What is the effect of long chains in polymers, without any side branches?

Answer 24

The molecules are closely aligned, so the attraction force between them is strong. The polymer is therefore strong and hard.

Question 25

What is a crystalline polymer?

Answer 25

One that has lots of areas in which there is a regular pattern to the way the molecules line up.

Question 26

What are the properties of crystalline polymers?

Answer 26

They are very strong, but can be brittle.

Question 27

What is the effect of lengthening the polymer chain?

Answer 27

The material becomes stronger, and the melting point rises as the molecules are larger and more attracted to each other.

Question 28

What is a plasticiser?

Answer 28

A small molecule used to keep polymer chains apart, weakening the attractive forces between the molecules.

Question 29

What is the effect of a plasticiser?

Answer 29

The material is made more flexible.

Question 30

Name an example of a polymer that can have a plasticiser added.

Answer 30

PVC is used for window frames, but can also have a plasticised added to make it suitable for raincoats.

Question 31

What is a thermoplastic?

Answer 31

A plastic that can be melted and moulded. Often used to make toys.

Question 32

What is a thermosetting plastic?

Answer 32

A plastic that does not melt when heated, due to the cross-links between the molecules.

Question 33

How could you increase the crystallinity of a polymer?

Answer 33

Remove branches, make the structure as flat as possible so that the chains can line up.

Question 34

What is the effect of drawing a heated polymer through a tiny hole?

Answer 34

The molecular chains will line up, increasing cristallinity and increasing tensile strength.

Question 35

Give an example of a polymer that is produced by drawing through a tiny hole?

Answer 35

Kevlar, used for bullet proof vests.

Question 36

What is a nanoparticle?

Answer 36

A particle that contains up to a thousand atoms.

Question 37

Name a natural nanoparticles?

Answer 37

Salt in seaspray

Question 38

Name a nanoparticle created by accident?

Answer 38

Carbon particulates when fuels burn

Question 39

What is nanotechnology?

Answer 39

The use and control of very small structures.

Question 40

What is a buckyball?

Answer 40

A sphere made from 60 carbon atoms, this is a very strong structure.

Question 41

Why is nanotechnology used with catalysts?

Answer 41

The surface area increases as the particles become smaller, and increasing surface area gives more sites for reactions to take place.

Question 42

What is a carbon nanotube?

Answer 42

A tube made out of carbon atoms.

Question 43

How long can a nanotube be?

Answer 43

The diameter is measure in nanometers, and the length can be millimetres, so they can be millions of times longer than they are wide

Question 44

Why can nanoparticles show different properties to larger particles of the same material?

Answer 44

They have a very large surface area.

Question 45

Name some everyday uses of nanoparticles.

Answer 45

Silver to kill bacteria, put into plastic food containers, socks, bandages. Titanium oxide is used in sunscreens, the small particles are invisible but still stop sunburn. People therefore don't have to look ghostly white at the beach.

Question 46

How do you make a composite using nanoparticles?

Answer 46

They are mixed with other substances to eg make rubber harder wearing.

Question 47

What are the risks of nanotechnology?

Answer 47

New technology, so not totally known. eg silver nanoparticles could be washed out of clothes and coninue killing bacteria, first at the sewage works where they are needed to clean the water, then in the environment. Also used in cosmetics, nanoparticles can cross the skin so effect on human health unknown.

Question 48

Why do some people think there is no risk with nanoparticles?

Answer 48

They occur naturally, eg soot and volcanic dust. Hmm.. maybe volcanic lava is also not risky? :D

Question 49

Why do other people think that there are risks with the new technology of nanotechnology?

Answer 49

There has not been time to test; there are new nanoparticles so the safety of the natural ones may not be relevant.

Question 50

Why do some people want nanotechnology stopped?

Answer 50

They want proof that the new technology will not create health and environmental risks.

Question 51

What is a risk?

Answer 51

The chance of an event happening, and the consequences if it did.