Please enable JavaScript.
Coggle requires JavaScript to display documents.
Uses of Metals and Alloys, Metal ores and extraction of Metals, Rusting -…
Uses of Metals and Alloys
Iron, aluminium and copper properties
dense
shiny
high melting point
strong/ hard to break
malleable
good conductor of electricity and heat
uses of iron
because it is malleable
used to make gates and railings
however corrodes easily
uses of aluminium
doesn't corrode easily
reacts with oxygen in air to form aluminium oxide
drinks cans- doesn't rust
forms a protective layer to stop further reactions taking place
useful when weight matters e.g aeroplanes
less dense than iron so it is lighter
uses of copper
extremely good conductor of heat and electricity
used in electrical components as wiring as it has low resistance
so is efficient at transferring energy
used in heating systems
allows speedy transfer of heat to surroundings
Metal ores and extraction of Metals
oxidisation is the addition of oxygen
the substance that oxidises the metal is the oxidising agent
reduction is the removal of oxygen
the substance that reduces the metal is the reducing agent
most metals are found in ores and have to be separated
metals that are unreactive don't form compounds with other elements
they are found uncombined so you just have to dig them up
most metals do react with other elements to form compounds
the compound is called a metal ore
the most common type of reduction reaction uses carbon to separate the oxygen from the metal
but carbon can't be used for all metals
metal extraction is linked to order of reactivity
only metals less reactive than carbon can ne extracted with a reaction with carbon
they have to be extracted using electrolysis
Rusting
iron
comes into contact with
oxygen
& water
only rusts when:
iron + oxygen + water-> hydrated iron (iii) oxide
two main ways to prevent rust
barrier method
painting or coating with plastic
oiling and greasing
oiling used for moving parts
sacrificial method
zinc is used as a sacrificial metal
zinc is more reactive than iron
zinc will be oxidised instead of iron
coating of zinc can be sprayed- galvanising
or block can be bolted on