C2

Question 1

What are the chemicals we use made up of?

Answer 1

the materials we use are chemicals or mixtures of chemicals, and include metals,
ceramics and polymers

Question 2

What are synthetic materials alternatives for?

Answer 2

There are synthetic materials that are alternatives to materials from living things. Raw materials from the Earth’s crust can be used to make synthetic materials

Question 3

What does crude oil contain?

Answer 3

Crude oil (petroleum) consists mainly of hydrocarbons, which are chain molecules of varying lengths made from carbon and hydrogen atoms only.

Question 4

What do you need to consider before choosing a material for a particular job?

Answer 4

It’s range of properties

Question 5

What is tensile strength?

Answer 5

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

Question 6

What is compressive strength?

Answer 6

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

Question 7

What does the effectiveness and durability of a product depend on?

Answer 7

It depends on the materials used to make it:

• some materials can be drawn into thin filaments with greater tensile strength. They can be spun into fibres and woven into cloth.
• ropes are made by winding fibres together. The more that are wound, the greater the strength

Question 8

What is a good way to estimate the true value?

Answer 8

Calculating the mean(average)

Question 9

What are metals?

Answer 9

Metal are chemicals which are shiny, malleable and electrical conductors

Question 10

What are ceramics?

Answer 10

Ceramics include clay, glass and cement. They are hard and strong.

Question 11

What are polymers?

Answer 11

Polymers are very large molecules made when many smaller molecules join together. The smaller molecules are called monomers.
E.g. Concrete is a mixture of sand and cement. Bronze is a mixture of copper and tin.

Question 12

What are natural materials?

Answer 12

Natural materials from living things which need little processing are cottons and paper from plants an silk and wool from animals. Other natural raw materials which at extracted from the Earth’s crust are limestone, iron ore and crude oil.

Question 13

What are synthetic materials?

Answer 13

Synthetic materials are manufactured by chemical reactions using raw materials. Synthetic materials are alternative to natural materials from living things.

Question 14

Why have synthetic materials replaced natural materials?

Answer 14

• some natural materials are in short supply
• they can be designed to give particular properties
• They are often cheaper and can be made in the quantity needed

Question 15

What happens when fuels burn in oxygen?

Answer 15

CO2 + H2O are made

Question 16

Should the number of atoms of each element I the reactants be the same as the products?

Answer 16

Yes

Question 17

What is nearly 90% of cruel oil used as?

Answer 17

Fuel

Question 18

How is crude oil separated?

Answer 18

Crude oil is separated by fractional distillation:

• the oil is heated up which turns it all into gases
• the distillation tower gets cooler as it gets higher
• gas molecules condense into liquids when they cool
• liquids with similar boiling points collect together. We call these fractions

Question 19

What different liquids are produced through fractional distillation?

Answer 19

40°C bottled gas
40-175°C petrol and chemicals for synthesis
175-260°C jet fuel, paraffin for lighting and heating
260-330°C diesel fuels
Up to 490°C lubricating oils, waxes, polishes
Up to 580°C fuels for ships, factories and central heating
Over 580°C bitumen for roads and roofing

Question 20

What at the properties of the crude oil liquids?

Answer 20

• liquids in each fraction have similar boiling points
• molecule chain lengths are similar sized within each fraction
• the smaller the molecule chain length, the smaller the forces between molecules, the lower the boiling point, and the higher it will rise during fractional distillation.

Question 21

What do larger molecules in order to form a gas?

Answer 21

Larger molecules need more energy to break them out a liquid to form a gas, So have higher boiling points.

Question 22

What is a polymer?

Answer 22

A polymer is a large molecule made by joining smaller molecules called monomers.

Question 23

How are polymers made?

Answer 23

Polymerisation

Question 24

What is PET?

Answer 24

PET is a polymer used to make drink bottles. PET is clear, strong, has a low density and does not shatter, making it a superior metal to glass.

Question 25

How can polymer chains be altered?

Answer 25

By replacing hydrogen atoms with other atoms or groups of atoms. Each new polymer has its own set of properties and uses.

Question 26

The stronger the force of a molecule:

Answer 26

• the more energy is needed to separate the molecules

- the higher the melting points

Question 27

What do the properties of polymers depend on?

Answer 27

•how their molecules are arranged and held together

Question 28

What are the properties of low density polyethene?

Answer 28

Low density polyethene (LDPE) has long molecules with branches. The branches keep molecule chains apart so the forces between different molecules are weak (e.g plastic bags)

Question 29

What are the properties of high density polyethene?

Answer 29

High density polyethene (HDPE) has long chains but no branches so the molecules are aligned close to each other. HDPE is much stronger and is used to make long-lasting items which are hard as stiff, such as water pipes. HDPE has a high degree of crystallinity.

Question 30

What does having a high degree of crystallinity mean?

Answer 30

There are lots of areas with regular patterns in the way the molecules line up.

Question 31

What are the properties of high crystalline polymers?

Answer 31

•strong with high melting points but can be brittle

Question 32

How can you improve polymers?

Answer 32

•making the molecule chain longer makes it stronger. Longer chains need more force to separate them. Longer chains have higher melting points than short chains.

Question 33

What are plasticisers used for?

Answer 33

• to make a polymer soft

* they are small molecules inserted into polymer chains to keep them apart, weakening the forces between them

Question 34

What can all plastics be classified as?

Answer 34

Thermosetting (remains rigid when set)

Thermoplastics (melt easily when heated)

Question 35

How can crystallinity be increased?

Answer 35

Crystallinity can be increased by removing branches in the main polymer chain and making the chains as flat as possible. This is so that the molecule chains can line up neatly. Drawing polymers through a tiny hole when heated makes the molecule chains like up, increasing crystallinity and forming a higher tensile strength fibre. Materials that have been treated in this way include bulletproof vests and sail material (Kevlar)

Question 36

What are nanoparticles?

Answer 36

Nanoparticles are materials containing up to 1000 atoms

Question 37

What is nanotechnology?

Answer 37

Nanotechnology is the use and control of very small structures. The size of these structures is measured in manometers (nm). A manometer is one millionth of a millimetre

Question 38

How can nanoparticles be built up?

Answer 38

Nanoparticles can be built up from individuals atoms. These structures are about the same size as some molecules.

Question 39

What are buckyballs?

Answer 39

Very strong carbon spheres made of 60 carbon atoms. Carbon nanotubes are being designed in labs.

Question 40

Why are some nanoparticles effective catalysts?

Answer 40

Some nanoparticles are effective catalysts as they have a large surface area. Increasing surface area provides more sites for reactions to take place. Surface area increases when a lump of solid is cut up into bits. Nanoparticles have very large surface areas and so they show different properties to larger particles of the same material.

Question 41

What are silver nanoparticles good at?

Answer 41

Killing bacteria

They can be added to fibres and woven into socks.

Question 42

What can titanium oxide nanoparticles do?

Answer 42

Make sunscreen transparent and absorb UV light.

Question 43

What are composites and what can they do?

Answer 43

Nanoparticles can be mixed wit other materials like metals, ceramics and plastics. These combined materials are called composites. They are stronger harder wearing. Adding nanoparticles to:

• plastic sports equipment makes it stronger
• tennis balls makes them stay bouncy for longer
• rubber used in tyres make them harder wearing

Question 44

How does graphite form?

Answer 44

Graphite forms in strong sheets that separate easily. Individual graphite sheets one-atom thick are known as graphene sheets. Graphene tests can bd rolled into carbon nanotubes. These are super-strength materials

Question 45

Are nanoparticles safe?

Answer 45

Nanoparticles are small enough to pass through the skin into blood. The possible medical effects of this are not yet known. One fear is that nanoparticles in the air might be breathes in and cause lung or brain damage. Some people think that because they occur natural they pose no threat whilst others argue against this because new nanoparticles with new properties have been manufactured.

Question 46

What is a risk?

Answer 46

Risk is defined as the change of an event occurring, and the consequences if it did. Some people want proof that new nanotechnologies will not create health and environmental risks.