C2 - Material Choices

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What are all materials made out of?
Chemicals
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What is a mixture and give some examples?
A mixture contains different substances that are not chemically joined together. For example, salt and sand
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What materials are made naturally from plants?
Wood and paper are from trees. Cotton comes from a cotton plant.
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What materials are made naturally from animals?
Wool comes from sheep. Silk is made by the silkworm larva. Leather comes from cows.
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What is a synthetic material?
A material that is man-made.
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What materials are made synthetically?
Rubber, clothes made of nylon and polyester, and most paints
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Where did rubber use to come from?
From the sap of the rubber tree
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Why is rubber now made in factories?
Because you can now control its properties, which make it suitable for different uses
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Where do the raw materials for synthetic materials come from?
The materials come from the Earth's crust
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What are the different properties that a material can have?
Melting point, strength (Tensile strength and compressive strength), stiffness, hardness and density
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What is melting point?
The temperature where a solid turns into a liquid
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What is tensile strength?
How much a material can resist a pulling force
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What is compressive strength?
How much a material can resist a pushing force
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What is strength?
How good a material is at resisting a force
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What is stiffness?
How good it is when a force is bending it
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What is hardness?
How difficult the material is to cut into it
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What is density?
A materials mass per unit of volume
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What do the uses of a material depend on?
It depends on its properties
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What does a products effectiveness depend on?
The raw materials it is made of
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What is crude oil a mixture of?
Hydrocarbons
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When do the properties of a hydrocarbon chain change?
When the chain gets longer
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What properties does a short-chain hydrocarbon have?
They have low boiling points and are often gases
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What properties does a long-chain hydrocarbon have?
They have high boiling points and can be quite viscous
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What are the 2 types of bonds in crude oil?
Covalent bonds and intermolecular forces
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How is crude oil refined?
Through fractional distillation
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In fractional distillation what are the hydrocarbons separated into?
The different boiling points
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What does the use of a hydrocarbon depend on?
The length of the molecule chains
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What is crude oil refined for?
Fuels and lubricants
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What is the process of making new compounds called?
Chemical syntheis
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What is a polymer?
Lots of monomers joined together
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How would the length of hydrocarbon affect the forces between the molecules?
The forces are greater when the molecules are bigger
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What is the name of the process that joins monomers to make a polymer?
Polymerisation
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Name 2 examples of materials that have replaced old ones.
Nylon and polyester have replaced cotton and wool. Also, PVC has replaced wood when making window frames.
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How would the polymer chains be arranged if the material has a high density?
The chains would be packed closely together
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How would the polymer chains be arranged if the material has a low density?
The chains would be spread out.
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If there are weak bonds in the chains what happen?
The chains can slide over each other easily. This means the material can be stretched easily and has a low melting point.
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If there are strong bonds in the chain what happens?
There is a higher melting point and the material can't easily be stretched.
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What are crosslinks?
Chemical bonds between polymer chains
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What can be modified to give them different properties?
Polymers
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What are the properties of a polymer with a short chain?
Easy to shape and have lower melting points
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What are plasticisers?
They are added to a polymer so that it is softer and easier to shape.
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How do plasticisers work?
They reduce the forces in the chain
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How can polymers be made stronger?
By adding cross-linking agents
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What is a crystalline polymer?
A polymer that has no branches, so the chain can fit closely together. They have a higher density and have a higher melting point
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What does nanotechnology involve?
Studying structures that are very small.
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Give an example of a natural nano particle.
Seaspray
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Give an example of an accidental nano particle.
Soot particles from combustion
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Why are nano particles added to a material?
To change its properties
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What can silver nano particles do?
They can kill bacteria, which makes them useful for wound dressing
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Why is there a concern for nanoparticles?
Because people believe that the effects haven't been fully investigated.
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Other cards in this set

Card 2

Front

What is a mixture and give some examples?

Back

A mixture contains different substances that are not chemically joined together. For example, salt and sand

Card 3

Front

What materials are made naturally from plants?

Back

Preview of the front of card 3

Card 4

Front

What materials are made naturally from animals?

Back

Preview of the front of card 4

Card 5

Front

What is a synthetic material?

Back

Preview of the front of card 5
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