Paper 2- Unit 10 (Triple only) Flashcards
What is corrosion?
the destruction of a material
by a chemical reaction
with substances from the enviroment
What is rusting?
the corrosion of iron
conditions for rusting
oxygen
water
corrosion prevention
paint a protective coating
greasing
electroplating
Why is aluminium resistant to corrosion?
reacts with oxygen
to form a protective layer
of aluminium oxide
What is sacrificial protection?
When a more reactive metal
is used to protect a less reactive metal
Why can zinc be used to protect iron?
Zinc is more reactive than iron
chemicals react with zinc first
protecting the iron
What is an alloy?
a mixture when at least one element is a metal
Why are pure metals soft?
Layers of metal ions
can slide over each other
when force is allied
Why are alloys hard?
Layer of metal ions are distorted
due to different shaped elements
so they can’t slide over each other
describe the structure of a thermosetting polymer
large polymer layers
with strong covalent bonds (cross links)
between the layers
Explain why thermosetting polymers have higher melting points than thermosoftening
large polymer layers
with strong covalent bonds (cross links)
between the layers
lots of energy needed to break these
Describe the structure of a thermosoftening polymer
Large polymer chains
with weak intermolecular forces of attraction
between the chains
Explain why thermosoftening polymers melt when heated
weak intermolecular forces of attraction
between the chains
easily broken
when chains vibrate and melt
What is a ceramic?
wet clay
that has been heated
What is a composite?
a mixture of two materials
a binder
and a reinforcer
Name some composites
Concrete
fibre optic cables
cement
What is the useful product of the haber process?
ammonia
formula for ammonia
NH3
Conditions of the haber process
450 oC
Iron catalyst
200 atm
Why is the reaction chamber cooled at thee end of the haber process?
to condense the ammonia
and remove it
word equation for the haber process
nitrogen + hydrogen ammonia
Why is the haber process carried out at 450 oC
compromise (optimum)
increasing the temperature decrease yield of ammonia
quick rate of reaction
any lower and reaction is too slow
Why is the haber process carried out at 200 atm?
compromise (optimum)
increasing the pressure increases the yield of ammonia
any lower and reaction too slow
any higher and it is too dangerous/expensive
