C2- Material choices

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  • Created by: ElishaG
  • Created on: 18-05-16 17:44
What are all materials made up of?
Chemicals.
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What is a mixture?
A mixture contains two different substances that are NOT chemically joined together.
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What is a compound?
A compound contains two different substances that ARE chemically joined together.
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Give examples of materials we get from plants.
Wood and paper from trees. Cotton from cotton plant.
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Give examples of materials we get from animals.
Wool from sheep. Silk made by silkworm larva. Leather fro cows.
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What are synthetic materials?
Man made materials.
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Where is rubber for car tyres from?
Sap of rubber tree.
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What are the benefits of synthetic materials?
You can control its properties and make it suitable for different purposes.. E.g. wetsuits.
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Give examples of synthetic materials used to make clothing, how can we modify properties?
Nylon and polyester. Can make them water-proof, stretchy, sparlly.
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What are most paints made of?
Mixture of man made chemicals.
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Which metals are used to make alloys?
Aluminium and chromium.
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What are the 5 properties of a material?
Melting point, Strength (tensile and compressive), Stiffness, hardness, density.
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What is melting point?
Temperature a solid turns to liquid.
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What is strength?
How good a material is at resisting a force.
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What is tensile strength?
How much a material can resist a pulling force. e.g. ropes, cables need good tensile strength.
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What is compressive strength?
How much a material can resist a pushing force. E.g. bricks.
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What is stiffness?
A stiff material is good at not bending when a force is applied to it.
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What is hardness?
How difficult it is to cut into a material.
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What is the hardest material found in nature?
Diamond.
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What is density?
A materials mass per unit volume e.g. g/cm cubed.
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True or false-Objects less dense than water will sink.
False- Objects less dense than water will float (like ice). Objetcs more dense than water will sink.
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What are properties of plastic?Give examples of uses.
Fairly strong,hard,stiff. Some have low density. Some are mouldable. e.g. cases for tv's, computers, kettles.
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What are properties of rubber?Give examples of uses.
Strong but soft and flexible. Mouldable. e.g. rubber car tyres.
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What are properties of nylon fibres?
Soft and flexible. Good tensile strength. e.g. ropes and clothing fabric.
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What is the effectiveness of a product?
How good it is at the job it's supposed to do.
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What is durability?
How long a product will last.
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What properties must cooking utensils have?
High melting point, non toxic.
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What properties must toys have?
Non-toxic, strong, stiff, low density e.g.plastic.
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What properties must clothing fabrics have?
Good tensile strength (but not stiff), high flame resistance.
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What is crude oil?
A mixture of hydrocarbons.
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What is the boiling point of short chain molecules like?
Low melting and boiling point, often gases.
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What is the boiling point of long chain molecules like?
High melting point, can be quite viscous.
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What does viscous mean?
Thick and sticky.
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What are the two types of important bond in crude oil?
1)Strong covalent bond between carbons and hydrogens of each hydrocarbon molecule.2)Intermolecular forces of attraction between different hydrocarbon molecules.
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What happens to the molecules when crude oil is heated?
They are supplied with extra energy, may have enough to overcome intermolecular forces and turn to gas.
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Why don't the covalent bonds break?
They are much stronger than intermolecular forces.
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True or False- the intermolecular forces break easily in small molecules than in bigger molecules?
True- because intermolecular forces are much stronger between big molecules.
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What is the name of the process where crude oil is separated?
Called refining, done by Fractional distillation.
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When hydrocarbons are separated into groups, what are the differences? What are the different groups called?
Differences are boiling points and chain length. Groups are called fractions.
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What are useful products from fractional distillation?
Refinery gas, petrol, naphtha, kerosene(jet fuel), diesel, lubricating oil, bitumen(tarmac)
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What are most hydrocarbons used to produce?
Fuels.
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What are a small amount of hydrocarbons used to produce?
New compounds to use in: plastics, medicines, fertilisers and food.
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What is done with the less useful hydrocarbons?
Split apart to make more useful hydrocarbons and ethene(useful for making plastics).
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What is Chemical synthesis?
The process of making new compounds.
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What does polymerisation mean?
Lots of small molecules linking together.
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How are plastics formed?
When lots of monomers (small molecules) join together to make a polymer (Long molecule)
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Give examples of properties of polymers and their uses.
Strong,rigid-high density polythene(milk bottles). Light, stretchable- low-density polythene (plastic bags). Strong, durable,stretchy-PVC(Window frames, stretchy kind synthetic leather).
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Give two examples of how polymers have replaced natural materials.
1)Synthetic fabrics (nylon, polyester) used to replace (cotton,wool,silk) lighter, more durable water resistant, often cheaper.2)Rigid PVS instead of wood for window frames. Weather resistant, strong, durable.
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If polymer chains are packed close together, what will the density be like?
High density.
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If a polymers chains are spread out, what will the density be like?
Low density.
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How does the force between polymer chains affect its properties?
Weak forces-plastic stretched easily, low melting point. Strong forces-higher melting point, can't be stretched easily.
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True or False-The stronget the bonds/forces between polymer chains, the more energy is needed to break them apart, the higher the melting point.
True.
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How can chain length modify polymers?
Short chain length- easy to shape, lower melting point. Longer chain length- stiffer, higher melting point.
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How can cross-links modify polymers?
Make chains chemically bond together- makes polymer stiffer, stronger, more heat resistant.
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How can plasticisers modify polymers?
Make it softer and easier to shape. Plasticisers get in between polymer chains and reduce forces between them.
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How can crystallinity modify a polymer?
Makes chains fit close together. Higher density, stronger, higher melting point.
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What is the size of nanoparticles?
1-100 nanometres.
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What is nanotechnology?
Branch of technology dealing with making and use of nanoparticles.
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How do nanoparticles occur naturally?
1)seaspray-sea produces nanoscale sale particles(present in atmosphere).2)Combustion-when fuels burn,nanoscale soot particles produced.
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What are uses of nanoparticles?
Plastics in sport equipment e.g. tennis rackets, golf clubs,golf balls, stronger and durable. Silver nanoparticles in polymer fibres for surgical masks and wound dressings-antibacterial properties.
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What gives nanoparticles different properties?
They are smaller than larger particles of same material,- have larger surface area to volume ratio.
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Why is it important that new nanoparticle products are tested?
The way nanoparticles affect body isn't fully understood.
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Card 4

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Give examples of materials we get from plants.

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