using our resources Flashcards
what are ceramics?
non metal solids with high melting points that aren’t made from carbon based compounds.
how are ceramics made from clay?
clay is soft and can be moulded into a shape.
when it is fired at high temperatures it hardens to form a clay ceramic.
what are composites?
one material embedded in another. (fragments of a material are surrounded by a matrix of another)
what are polymers?
large molecules formed by chaining monomers.
what effects the properties of a polymer?
the type of bond between polymer chains. (based on the monomers used)
how it’s made.
what it’s made from.
what is the difference between thermosetting and thermosoftening polymers?
thermosoftening polymers contain individual polymer chains twisted together. (they can be melted and remoulded)
thermosetting polymers contain monomers that can form cross links between polymer chains. (making them strong hard and rigid)
what are the properties of ceramics?
insulators of heat and electricity.
brittle. (aren’t flexible and break easily)
stiff. (how hard it is to deform)
what are the properties of polymers?
insulators of heat and electricity.
flexible.
easily moulded.
what are the properties of composites?
the properties of composites vary depending on what materials are used.
what are the properties of metals?
malleable. (can bend)
good conductors of heat and electricity.
ductile. (can be stretched)
shiny.
stiff. (how hard it is to deform)
what is an alloy?
a metal added to another element.
why are alloys stronger than metals?
adding another element to the metal disrupts the structure of the metal increasing hardness. (resistance to scratching and deforming)
what is bronze and brass made of?
bronze - copper + tin.
brass - copper + zinc.
what is corrosion?
where metals react with substances in the environment destroying them.
why does iron and steel corrode more than aluminium?
corrosion only happens on the surface of a metal where it is exposed.
when iron rusts the rust flakes off exposing more iron to be rusted.
however aluminium forms a protective layer when it corrodes (aluminium oxide) protecting the metal below it.
how can you prevent rusting? (2)
- coat the iron with a barrier to keep out oxygen and water. (painting electroplating oiling)
- sacrifice a more reactive metal to save the iron.
how is a galvanised object protected?
an object is sprayed with a coating of zinc which is protective.
if the zinc is scratched off the zinc around the scratch becomes a sacrificial metal.
how does the haber process work?
the haber process is used to make ammonia from hydrogen and nitrogen.
1. nitrogen is taken from air and hydrogen is taken from reacting methane with steam. (forming hydrogen and carbon dioxide)
2. hydrogen and methane are passed over an iron catalyst at a high temperature (450°c) and high pressure. (200 atmospheres)
3. an equilibrium is reached as the reaction is reversible.
4. ammonia if formed as a gas but cools in a condenser and is removed as a liquid.
what are the 3 main elements in NPK fertilisers?
nitrogen.
phosphorous.
potassium.
what do fertilisers do?
provide plants with the essential elements for growth.
