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C2
Tectonic plates = move 2.5cm per year.
= millions of years to form continents.
Iron core
Plate tectonics Theory
Convection currents in the mantle = plates move.
Mantle
Oceanic crust less dense than continental crust.
Just below crust = cold, rigid Collision between oceanic and continental plates
Deeper down = hot, can move = subduction and melting
Lithosphere
Plates cooler at ocean margins so sink
Crust + upper mantle
Made of tectonic plates
The development of the Plate Tectonics theory
Tectonic plates = less dense than mantle  float Wegner came up with continental drift in 1914.
Thin, rocky crust
Volcanoes – studied to predict eruptions
- to find out the Earth’s structure
Better predictions now – better
measurement techniques and theories –
still not 100%
People live there – fertile soil
Lava
Slow cooling = big crystals
Thicker lava = more dangerous eruption
Rock
Lava
Eruption
Iron rich basalt
Runny
Safe
Silica rich rhyolite
Thick
Explosive
Not accepted by scientists – Wegner wasn’t a
geologist, it went against their ideas.
1960s – sea floor spreading discovered –
supported theory.
More research supports it. Theory accepted.
Plate tectonics is widely accepted
It explains lots of evidence
Discussed and tested by lots of scientists.
Problems with studying the Earth’s structure
Crust is too thick to drill through.
Have to use S and P waves from man-made
explosions
Earth’s structure
Construction Material
Made from
Aluminium/Iron
Ores
Bricks
Clay
Glass
Sand
Construction
Materials
Rocks used in construction
Limestone = soft - sedimentary rock - layers
Marble = hard- metamorphic rock - -made by
high temperature and pressure
Granite = really hard – igneous rock
Limestone
Quarrying destroys the landscape, causes noise, traffic and
dust.
Thermal decomposition
A reaction where heat is used to breakdown one substance
into at least two new substances.
Concrete
Cement + sand + gravel + water
then let it set.
Reinforced Concrete
Concrete + steel
calcium carbonate  calcium oxide + carbon dioxide
Composite material (mixture of
CaCO3

CaO
+
CO2
two materials = mixture of their
properties.)
Reinforced concrete is better
than normal concrete.
It is as hard as normal concrete
Steel makes it more flexible and
stronger in tension (when you
stretch it).
Cement = limestone and
clay heated together.
Extraction of Copper
- Extracted from its ore using carbon.
- Reduction reaction – because oxygen is
removed from the copper
- Then purified by electrolysis
Alloys
Mixtures containing one or more metals elements.
Alloy
Made from
Use
Amalgam
Mercury
Tooth fillings
Brass
Copper +
zinc
Musical instruments,
decorations, coins
Solder
Lead + tin
Join electrical wires
Smart Alloys
Shape memory – can bend, warm up and then it
returns to shape.
Nitinol – bendy glasses frames – returns to original
shape after bending
Metals and Alloys
Purification of Copper details
Impure copper as anode.
Pure copper as cathode
Copper sulfate solution as electrolyte
Advantages of recycling copper
Low melting point – easy to melt
down – less energy needed than
Cathode gains mass as copper is deposited. for mining it.
Cu2+ + 2e-  Cu – reduction (RIG)
Cheaper than extracting it from its
ore.
Anode loses mass as copper dissolves.
Saves copper resources
Cu – 2e-  Cu2+ - oxidation (OIL)
Disadvantages of
recycling copper
Getting the public to do it
Has to be sorted from
other metals
Pure copper must not be
mixed with less pure.
Rusting
Is an oxidation reaction because oxygen is added to
the iron.
Iron + oxygen + water  hydrated iron (III) oxide
Rusting happens faster when the water is salty or
acidic
Iron
Aluminium
More dense
Less dense
magnetic
Not magnetic
corrodes
Does not corrode
Malleable
Recycling and Cars
EU law says 85% of a car should be
recyclable.
Advantages of recycling car parts
1. Saves metal resources because less
has to be mined.
2. Saves money and energy
3. Less crude oil is used to make plastic
parts
4. Glass has been recycled for a long
time so is easy to do.
5. Batteries contain toxic material so it is
better that this is not dumped.
Good electrical conductor
Disadvantage
All the different materials need to be
separated first.
Aluminium does not corrode because
• A layer of aluminium oxide forms on the surface
• Aluminium oxide is strong
Car made out of
Alloys
steel
Have properties that are different to the
metals they are made from which can make Car will be
cheaper
them more useful
Steel is harder and stronger than iron
Steel is less likely to corrode than iron.
Making Cars
Car made from aluminium
Car body will be lighter so you
get better fuel economy.
Car body will corrode less so
the car will last longer
Making Ammonia
Ammonia is made in the Haber process
nitrogen + hydrogen
ammonia
N2
+
H2
NH3
Needs:
• Nitrogen – from the air
• Hydrogen – from natural gas or crude oil
• Iron catalyst –increases the rate and does
not affect the % yield
• High pressure – higher pressure increases
the % yield of ammonia
• Temperature of about 450oC – high
temperature decreases the % yield of
ammonia but gives a faster reaction – we
choose a compromise temperature for a
high rate and quite high yield.
Unreacted nitrogen and hydrogen are
recycled.
Costs and Industry
High pressure – high cost of equipment
High temperature – high energy cost
Catalyst – reduces cost by increasing rate
Recycling the unreacted nitrogen and
hydrogen reduces costs
Automation – reduces the wages bill
Rate and % yield = high enough for sufficient
daily rate.
Low % yield sometimes ok if the starting
materials are recycled many times.
Optimum conditions = lowest cost (not
fastest reaction or highest yield)
Ammonia
Uses
Ammonia is used to make fertilisers
and nitric acid.
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