C15 Using Our Resources Flashcards
What is rust?
The corrosion of iron
what are the conditions needed for rusting?
air and water
what is the chemical name of rust?
hydrated iron oxide
how can rust be prevented?
- paint
- oil/grease
- plastic coating
- less reactive metal
- more reactive metal
what is sacrifical protection?
a method of preventing rusting where a more reactive metal than iron is attached or coated on an object
what does galvanised mean?
iron or steal objects that are protected from rusting by a thin layer of zinc metal on their surface
when is sacrificial protection used?
when the conditions are harsh such as in seawater
what accelerates rusting?
seawater
what is an alloy?
a mixture of two or more elements where at least one is a metal
why are alloys used?
it makes the metal harder
this is because differently sized particles make it harder for layers to slip over each other
what are some alloys of copper and what are they made from?
- bronze (copper ant tin)
- brass (copper and zinc)
why is gold alloyed and what is it alloyed with?
it is alloyed to make it harder
it is usually alloyed with copper
what are steels?
alloys of iron with carbon and other elements
why is pure iron not used?
it is too soft to be usefull
how can you change the properties of steel?
carefully controlling quantities of carbon and other elements added to the iron
how are carbon steels made?
removing most of the carbon from the iron in the blast furnace
what are the properties of high carbon steels?
very hard but brittle
what are the properties of low carbon steels?
softer and more easily shaped
what are the substances in stainless steel?
chromium
nickel
iron
what are the properties of stainless steels?
resistant to corrosion
how can the properties of a polymer be altered?
- different monomers
- the conditions of the reaction
what are the conditions to produce low density poly(ethene)?
high pressures
a trace of oxygen
what is the structure of LD poly(ethene)?
the polymer chains are randomly branched and cannot pack closely together
what are the conditions to produce high density poly(ethene)?
catalyst
50 degrees C
slightly raised pressure
what is the structure of HD poly(ethene)?
straighter chains that can pack more closely
what are thermosoftening polymers?
polymers which will soften or melt easily when heated due to their weak intermoleculular forces
what are thermosetting polymers?
polymers that do not melt when heated
why do thermosetting polymers not melt?
they have ‘cross-links’ (covalent bonds between chains) which stop them from softening
what is soda glass made of?
heating sand, limestone and sodium carbonate
what is borosiliate glass made from?
sand and boron trioxide
what are the properties of borosiliate glass?
it melts at a higher temperature than soda-lime glass
what are ceramics?
objects made from clay such as pottery and bricks
what compounds does clay contain?
metal compounds
non-metals with ionic bonding and covalent bonding
how are clay ceramics made?
shaping wet clay and then heating in a furnace
why are ceramics brittle?
a sharp blow can distort the layers in the structure so that ions with like charges are adjacent and repel each other which cracks the object
what are the two materials in composite materials?
- matrix (one acting as a binder)
- other material which give structure or strength
why are composite materials used?
theu improve a desirable property than neither of the original materials could offer alone
why do plants need nitrogen?
they need it to grow as it is needed to make proteins
why can plants not obtain nitrogen from the air?
the gas is insoluble in water and most plants can only absorb a soluble form of nitrogen
what are the raw materials to make ammonia in the Haber process?
- nitrogen from the air
- hydrogen from natural gas
what are the conditions of the Haber process?
- 450 degrees C
- 200 atmospheres of pressure
- iron catalyst
what happens to unreacted nitrogen and hydrogen in the haber process?
it is recycled back into the reaction vessel
how is ammonia separated from unreacted hydrogen and nitrogen?
cooling the gases so that the ammonia liquifies
why is a pressure of 200 atmospheres used in the Haber process?
to increase the yield of ammonia
if higher pressures are used, the plant would be too expensive to run and build
why is a temperature of 450 degrees C used for the Haber process?
lower temperatures would increase the yield but it would produce too slowly?
what is the effect of a catalyst in the Haber process?
it speeds up the rate of the forward and backward reaction so causes ammonia to be produced more quickly
what is produced when ammonia is neutralised with sulfuric acid?
ammonium sulfate fertiliser
what is used to make ammonium phosphate fertiliser?
ammonium sulfate fertiliser and phosphoric acid
or
phosphate rock is reacted with nitric acid to produce phosphoric acid
this is then neutralised with ammonia
what are NPK fertilisers?
mixtures of compounds which supply nitrogen, phosphorus and potassium
what are the sources of phosphorus?
deposits of phosphate containing rock which is dug or mined
where does potassium come from for NPK fertilisers?
potassium salts potassium chloride or potassium nitrate mined from the ground
what is the main compound of nitrogen in NPK fertilisers?
ammonium nitrate
how is ammonium nitrate made?
ammonia is used to make nitric acid
nitric acid is reacted with more ammonia
what is single superphosphate?
when phosphate rock is treated with sulfuric acid which mades a mixture of calcium sulfate and calcium phosphate
how can you make triple superphosphate?
if phosphate rock is treated with phosphoric acid
