Chemistry - C2

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  • Created by: L_Georgie
  • Created on: 10-03-16 19:03
Give an example of materials the are natural and where they come from.
Wood and paper from a tree, Cotton from a plant, wool from sheep, silk from a silkworm and leather from cows.
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Give an example of man-made (synthetic) materials.
Rubber made in a factory, nylon, polyester and paint.
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What advantages are there of man-made materials?
The properties of the materials can often be controlled by the manufacturer making it suitable for it's purpose.
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What is the definition of tensile (or tension) strength?
How much a material can resist a pulling force.
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What is the definition of compressive strength?
How much a material can resist a pushing force.
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What is the definition of stiffness?
How much a material can resist bending when a force is applied to it.
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What is the definition of hardness?
How difficult it is to cut into a material.
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What effects the properties of products?
The materials it is made of.
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What properties would be suitable for a cooking utensil?
High melting point, non-toxic and strong
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What is crude oil a mixture off?
Hydrocarbons of varying lengths.
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What are the properties of a short-chain hydrocarbon?
They often have lower boiling points and are normally gasses.
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What are the properties of a long-chain hydrocarbon?
They often have high boiling points and can be quite viscous.
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What are the two important types of bond in crude oil?
The covalent bonds between the carbons and hydrogens in each hydrocarbon molecule and the intermolecular forces between different hydrocarbon molecules.
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What happens when a crude oil mixture is heated?
The molecules are supplied with extra energy which makes the molecules move around more and eventually it may have enough energy to overcome the intermolecular forces and it can escape as a gas.
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Why do intermolecular forces break much more easily in small molecule than they do in big molecules?
Because the intermolecular forces of attraction are much stronger between big molecules than they are between small molecules.
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Why do big molecules have higher boiling points than smaller ones?
Because more energy is needed for them to break out of a liquid and form a gas.
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What is the process of separating crude oil called and how is it done?
Refining and it's done by fractional distillation.
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What happens in fractional distilation?
Hydrocarbons are separated into groups with different boiling points.
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Name some products that could be made with crude oil.
Petrol, jet fuel, diesel, lubricating oil.
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What things can the compounds produced with crude oil be used in?
Plastics, medicines, fertilisers and food.
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What is the definition of chemical synthesis?
Chemical synthesis is the process of making new compounds.
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How are plastics formed?
Plastics are formed when lots of small molecules called monomers join together to make a long molecule called a polymer. This normally happens under high pressure.
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What are the properties of high-density polythene and what can it be used for?
It is strong and rigid and is used to make things like plastic milk bottles.
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What are the properties of low-density polythene and what can it be used for?
It is light and stretchable and is used to make things like plastic bags and squeezy bottles.
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What can rigid PVC be used to make?
Window frames and piping.
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What can the stretchy PVC be used to make?
It can be used to make synthetic leather.
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Why are synthetic fibres (nylon and polyester) often used to replace natural materials are there any areas where natural materials are better than synthetic?
Synthetic fabrics tend to be lighter, more durable, water-resistant and often cheaper. However synthetic materials are often uncomfortable when you wear them next to your skin.
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Why has rigid PVC largely been used to replace wooden window frames?
PVC window frames are more weather-resistant, stronger and more durable then wooden ones. Also they don't need painting every few years like wooden ones need to.
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What is the link between polymer chains arrangement and there density?
If the polymer chains are packed close together the material will have a high density. If they are spread out then the material will have a low density.
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What happens if polymer chains are held together by weak forces?
The chains are free to slide over each other which means the plastic can be stretched easily and have a low melting point.
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What happens if polymer chains are held together by strong bonds between the chains?
They will have a high boiling point and can't be easily stretched.
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Why cant polymers with strong forces be stretched easily?
The crosslinks hold the polymer chains firmly together and so they can't slide over each other.
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What happens to polymers if a cross-linking agent gets added?
The agent chemically bonds the chains together forming crosslinks and making the polymer stiffer, stronger and less heat-resistant.
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What happens if you add a plasticiser to a polymer chain and how does it do that?
It makes the polymer softer and easier to shape, these work by getting in between the polymer chains and reducing the forces between them.
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What are the chains like in a crystalline polymer and what are it's properties?
The polymer has straight chains with no branches which allow them to fit close together. Crystalline polymers have a high density, are stronger and have a higher melting point.
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what is a nanoparticle and how big are they?
A nano-particle is a really tiny particle that is 1-100 nanometers across.
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How can nanomaterials occur naturally?
Through seaspray as it produces tiny salt particles.
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How can nanomaterials occur by accident?
Through combustion as it produces tiny soot particles.
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Why are nanoparticles added to plastics in sports equipment?
They are added as they make the plastic much stronger and more durable however they don't add any extra weight.
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Why are silver nano particles added to plasters?
They are added to plasters because they have antibacterial properties.
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Why are some people worried about the effect of nanoparticles?
They are worried because nanoparticles haven't been investigated properly and they think that nanoparticles could be small enough to get deep into your lungs.
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Other cards in this set

Card 2

Front

Give an example of man-made (synthetic) materials.

Back

Rubber made in a factory, nylon, polyester and paint.

Card 3

Front

What advantages are there of man-made materials?

Back

Preview of the front of card 3

Card 4

Front

What is the definition of tensile (or tension) strength?

Back

Preview of the front of card 4

Card 5

Front

What is the definition of compressive strength?

Back

Preview of the front of card 5
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