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40 Cards in this Set
- Front
- Back
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What is the melting point |
The temperature at which a solid turns into a liquid |
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What is tensile strength |
The force needed to break a material when it's being stretched |
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What is compressive strength |
The forced needed to crush a material a when it's being squeezed |
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What is the stiffness |
The force needed to bend a material |
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What is density |
Compares how heavy something is for its size |
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What are metals |
Chemicals which are shiny malleable and electrical conductors |
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What are ceramics |
They are hard and strong examples include glass and cement |
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What are polymers |
Large molecules used to make rubbers, plastic and fibres |
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What are natural materials |
Made from living things which need a little processing |
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Where can Raw materials be found |
The earths crust |
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What are synthetic materials |
Manufactured by chemical reactions using raw materials |
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Why are synthetic materials replacing natural materials |
Because natural materials are in short supply, They can be cheaper and made in the quantity needed, Can be designed to give particular properties
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What is crude oil made out of |
Hydrocarbons |
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What is 90% of crude oil used for |
Fuel |
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how is crude oil separated |
-The oil is heated up which turns it all into gases -The distillation tower gets cooler as it gets higher -gas molecules condense into liquid when cooled |
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What is the similarities of hydrocarbons in each fraction |
Have similar boiling points, Have similar chain lengths |
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What is a polymer |
Large molecule made by joining of many smaller molecules called monomers |
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What is polymerisation |
A process where polymers are made |
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The stronger the force in the polymer... |
The more energy is needed to separate it and the higher the melting point |
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What is LDPE |
Low density polyethylene |
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What is HDPE |
High density polyethylene |
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What are the properties of LDPE and what are they are used for |
LDPE has long molecules with branches which keep the molecules apart making them weak, flexible, soft and low melting point - plastic bag |
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What are the properties of HDPE and what are they are used for |
HDPE has long molecules with no branches which keep the molecules close making them strong, stiff, hard - water pipes |
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What does crystallinity mean |
Lots of areas with regular patterns in the way the molecules line up |
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What do plasticisers do to polymers |
Make polymers softer forcing the chains apart making them weaker |
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What is plasticised PVC |
It's Hardwearing and waterproof but also flexible |
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What are thermoplastics |
The soften when heated and can be moulded |
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What are thermosetting plastic |
Plastics that do not soften when heated because they contain cross links |
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What are composites |
Nanoparticles mixed with other materials such as metals, ceramics and plastics |
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What's the problem with using silver nanoparticles |
Could be washed out of clothing and get into sewage works then the silver could kill the useful bacteria used to clean water |
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What is the problem with nanoparticles and the risks |
They haven't been around long enough to know what risks could happen |
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What are microscopes used for |
They are used to view very small objects like human cells |
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How can nanoparticles be made |
Naturally, such as salt in Seaspray By accident, solid particulate when fuels burn Designed in laboratories |
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What is nanotechnology |
Use and control of very small structures |
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How big is a nanometer |
It's one millionth of a millimetre |
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What is a nanotube |
a carbon molecule in the form of a cylinder |
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What is a Bucky ball |
Very strong carbon spheres made of 60 carbon atoms |
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Why are nanoparticles effective as catalysts |
Because they have a large surface area. |
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What are silver nanoparticles used for |
They are good at killing bacteria so they are used for plastic container and plasters |
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What are titanium oxide nanoparticles used for |
Sun cream as it makes it transparent and absorbs U V |
