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
