Science - Chemistry - Using resources - C10 Flashcards
what are ceramics ?
non-metallic solids with high melting points that aren’t made from carbon based compounds
what are the properties of ceramics ?
good insulators of heat/electricity
brittle
stiff
what are the 2 types of ceramics ?
clay ceramics
glass
what is clay ?
a soft material when it is dug out of the ground so it can be moulded into different shapes
what happens when clay is fired at high temperatures ?
it hardens to form a clay ceramic
what is clay useful for ?
making pottery / bricks
what are properties of glass ?
generally transparent
moulded when hot
brittle
what is the most common type of glass ?
soda lime glass
how is soda lime glass made ?
by heating a mixture of limestone sand and sodium carbonate until it melts then cools
which glass has a higher melting point :
borosilicate glass
or
soda lime glass
borosilicate glass
how is borosilicate glass made ?
using a mixture of sand and boron trioxide
what are composites ?
made of one material embedded in another - fibres or fragments of a material are surrounded by a matrix acting as a binder
what does the properties of composites depend on ?
the matrix/binder and the reinforcement used to make them
what are the uses of composites ?
- wood
-fibreglass
-carbon fibre composites - concrete
how is wood made ?
cellulose fibres held together by lignin
give uses of wood ?
building material
give properties of wood
strong
versatile
attractive
what is fibreglass made of ?
fibres of glass embedded in a matrix polymer
give properties of fibreglass
low density
strong
what is fibreglass used for ?
skis
boats
surfboards
how are carbon fibre composites made ?
from carbon nanotubes or long chains of carbon atoms
give properties of carbon fibre composites
strong
light
what are carbon fibre composites used for ?
aerospace
sports car manufacturing
how is concrete made ?
from aggregate embedded in cement
give properties of concrete ?
strong
rigid
give uses of concrete
building material
what are polymers ?
large molecules formed when many small molecules called monomers join together
give properties of polymers ?
insulators of heat/electricity
flexible
easily moulded
give uses of polymers
clothes
insulators in electrical items
what are the 2 things which influence the properties of a polymer ?
the monomers its made from
the conditions under which it’s made
what do the monomers a polymer is made from decide ?
what type of forces form between the polymer chains
what are thermosoftening polymers ?
made of individual tangled chains of polymers
what are the properties of thermosoftening polymers ?
flexible
can be melted then remoulded
what kind of forces are between thermosoftening polymer chains ?
weak forces
what are thermosetting polymers ?
have cross links between their polymer chains
what happens to a thermosetting polymer when heated ?
it chars
what are the properties of thermosetting polymers ?
strong
hard
rigid
give an example of how reaction condition affects properties of polymers ?
- 2 types of poly(ethene) can be made :
Low density poly ethene
High density poly ethene
how is low density poly ethene made ?
by heating ethene to a moderate temperature at high pressure
what are the properties of low density poly ethene ?
flexible
what is low density poly ethene used for ?
bags
bottles
how is high density poly ethene made ?
at lower temperature and a lower pressure
give properties of high density poly ethene ?
rigid
when is high density poly ethene used ?
water tanks
drain pipes
give properties of metals ?
malleable
good conductors of heat and electricity
ductile
shiny
stiff
sonorous
what is copper used for and why ?
electrical wires - conducts electricity well, and is ductile
what is an alloy ?
mixtures of 2 or more metals or a mixture of a metal and a non - metal
why are alloys better than pure metals ?
man pure metals are too soft for uses
why are pure metals soft ?
their layers of atoms slide easily past each other
why are alloys harder than pure metals ?
they are made from atoms of different elements which have different sized atoms so the layers are distorted so it is more difficult for atoms to slide past each other
give properties of iron ?
soft
easily shaped
bendy
what is iron used to make ?
alloys called steels
how are steels formed ?
by adding small amounts of carbon to the iron
what are the properties of low carbon steel ?
easily shaped
what is low carbon steel used to make ?
car bodies
what are the properties of high carbon steel ?
strong
inflexible
brittle
what is high carbon steel used to make ?
blades
bridges
what are the properties of stainless steel ?
corrosion resistant
hard
what is stainless steel used for ?
cutlery
containers for corrosive substances
what is bronze an alloy of ?
copper and tin
what are the properties of bronze ?
hard
what is bronze used for ?
statues
decorative objects
medals
what is brass an alloy of ?
copper and zinc
give properties of brass ?
gold like appearance
malleable
what is brass used for ?
door fittings
water taps
why are gold alloys used ?
gold is too soft
what are gold alloys used for ?
jewelry
what makes gold alloys ?
zinc
copper
silver
what are the benefits of a gold alloy ?
cheaper
what is the amount of gold in an item described in ?
carats
what is pure gold described as ?
24 carat
what is aluminium used for ?
aircraft manufacture
why can’t pure aluminium be used ?
it is too soft
so it is alloyed with other metals to make it stronger
what is corrosion ?
when a metal is gradually destroyed by reacting with substances in the environment
give an example of corrosion ?
iron rusting
what needs to be present for corrosion ?
oxygen
water
what is rust also known as ?
hydrated iron oxide
what is the word equation for iron rusting ?
iron + oxygen + water - hydrated iron oxide
where does corrosion happen in a material ?
at its surface
why does corrosion happen at the surface of a material ?
it is exposed to air there
why will iron that wasn’t initially at the surface eventually corrode away ?
the iron initially at the surface will crumble and flake off to leave more iron available to rust
why aren’t objects made from aluminium completely destroyed by corrosion ?
the aluminium oxide that forms when aluminium corrodes doesn’t flake away so a protective layer is formed preventing any further corrosion happening
explain a rust experiment which shows oxygen and water is required for rust to form ?
- put an iron nail in a boiling tube with just water - it won’t rust
- put an iron in a boiling tube with just air - it won’t rust
- put an iron nail in a boiling tube with air and water it wil rust