Topic 10- Using Resources Flashcards
what do Humans use the Earth’s resources for
to provide warmth, shelter, food
and transport.
what do Natural resources, supplemented by agriculture do
provide food, timber,
clothing and fuels.
how are clay ceramics, including pottery and bricks made
by shaping wet clay and then heating in a furnace.
how is soda lime glass made
by heating mixture of sand, sodium carbonate and limestone
what is Borosilicate glass
made from sand and boron trioxide, melts at higher temperatures than soda-lime glass.
what do the properties of polymers depend on
-what monomers they are made
from
-conditions under which they are made.
For example, low density (LD) and high density (HD) poly(ethene) are produced from
ethene.
what are composites
made of one material embedded in another. Fibres or fragments of a material (known as the reinforcement) are surrounded by a matrix acting as a binder
what do the properties of a composite depend on
the properties of the materials it is made from
give some examples of composites
fibre glass, carbon fibre, concrete, wood
what is fibre glass?
- consists of fibres of glass embedded in a matrix made of polymer (plastic)
- low density (like plastic) and strong (like glass)- used for skis boats and surfboards
what is carbon fibre
- have polymer matrix
- reinforcement is made from long chains of carbon atoms bonded together (carbon fibres) or from carbon nanotubes
- strong and light- aerospace and sports car manafacturing
what is concrete
- made from aggregate (sand and gravel) embedded in cement
- strong- building materials (skate parks)
what is wood
natural composite of cellulose fibres held together by an organisc polymer matrix.
How is low density poly(ethene) made?
from ethene moderate temperature high pressure with a catalyst flexible- used for bags and bottles
how is high density poly(ethene) made?
from ethene lower temp lower pressure different catalyst more rigid- used for water tanks and drain pipes
what do the monomers that a polymer is made form determine?
the type of bonds that form between the polymer chains
these weak bonds between the different molecule chains determine the properties of the polymer
what are thermosoftening polymers
- contain individual polymer chains entwined together
- weak forces between the chains
- can melt them and remould them
what are thermosetting polymers?
- contain monomers that can form cross-links between the polymer chains, holding the chains together in a solid structure
- don’t soften when heated.
- strong, hard and rigid
give some properties of ceramics
- include glass and clay ceramics such as porcelain and bricks
- insulators of heat and elec
- brittle and stiff
what are ceramics
non metal solids with high mp that aren’t made from carbon-based compounds
give properties of polymers
- insulators of heat and elec
- flexible
- easily moulded
- clothing and insulators in electrical items.
give properties of composites
depend on the matrix/binder and reinforcement used to make them- so have many different uses
properties of metals
malleable
good conductors of heat and electricity, ductile (drawn into wires)
shiny
stiff
electrical wires, car body-work and cutlery
how are alloys made
by adding another element to the metal- this disrupts the structure of the metal, making it a harder material
how is steel made
by adding small amounts of carbon and sometimes other metals to iron.
what is bronze and what is it used for
copper & tin
bronze is harder than copper
used to make medals, ornaments and statues
what is brass and what is it used for
copper & zinc
more malleable than bronze and is used in situation where lower friction is required, such as in water taps and door fittings.
what is used to make jewellry
gold alloys
pure gold = soft
SO metals such as zinc copper and silver are used to harden the gold.
pure gold = 24 carat, so 18 carats = 18/24 parts are pure gold (75%)
what is used for aircraft
aluminium alloys
-low density
pure aluminium is too soft- so alloyed to make it stronger with other metals
what is corrosion
destruction of materials by chemical reactions with
substances in the environment.
what is an example of corrosion
iron rusting- both air and water are necessary for iron to rust
what is rust
hydrated iron(lll) oxide
iron + oxygen + water -> hydrated iron(lll) oxide
where does rusting happen
on the surface of a material where it’s exposed to the air
how does rusting occur
when the soft crumbly rust flakes off, more iron is left to rust away again- leading to corrosion
why isn’t aluminium completely destroyed by corrosion
Aluminium has an oxide coating that protects the metal from further corrosion.
what is the experiment that shows both oxygen and
water are needed for iron to rust?
1) iron nail in boiling tube with just water- no rust (boiled water removed o2)
2) iron nail in boiling tube with just air- no rust (calcium chloride can be used to absorb any water from the air)
3) iron nail in boiling tube with air + water- RUST!