The Earth' surface is made of large plates of rock
Earths structure
The Earth's surface is made up of large plates of rock
Tectonic plates
Seismic waves can tell us what's below the crust
Difficult to study th Earth structure
when you can't get at it directly
Seismic waves are used to
study Earth's structure
These are produced by earthquakes
or by setting of man made explosions
By measuring where it happened and
the time it takes for the waves to travel
through the Earth and can draw
conclusions about the structure of the
Earth
P-waves
Travel faster
throgh the
middle of the
core
suggesting it
is solid
S-waves
Travel through the mantle which is
solid, not deceted in be liquid
Plate Tectonics
Alfred Wegener hypothesised that Africa and South America were once connected and had previously been one continat
The theory of 'continental drift'
about 300 million years ago. He
called it Pangaea.
Pangaea brake into
different pieces and these
pieces slowly drifted apart
The theory was not
excepted at first but it was
proved by the mid-Atlantic
ridge
Volcanic eruptions
Volcanoes are formed
by molten rock
Oceanic and continental crust colliding causes volcanoes
Volcanic activity forms igneous rock
Igneous rock is made when any sort of
molten rock cools down and solidifies
Iron-rich basalt = runny+safe
Silica-rich rhyolite = thick+explosive
The there different types of rock
Sedimentary rock
Layers of rock are laid down in
lacks and seas over millions of
years so the layers get buried
under other rocks. the weight
squeezes out all of the water
from the rocks.
Limestone is a sedimentary
rock formed from seashells
Formed by the action of heat
and pressure on sedimentary
over a long period of time
So long as the rock does not melt they're classed metamorphic
If it
melts it
is called
magma
Marble is a metamorphic
rock formed from limestone
Igneous in 'volcanic eruptions'
Construction Materials
Aluminium and iron are
extracted from the ground
as ores
Glass is made by melting
limestone sand and soda
together
Bricks are made from clay
Clay is molded into bricks
then fired at a high
temperature
Limestone and clay
are heated to make
cement
These two are put in a
kiln to make serment
Reinforced concrete is steel support plus concrete
Extracting pure copper
Electrolysis is used to obtain very pure copper
Reduction
The gain of electrons
or the removal of
oxygen
Cu2+ + 2e- --> Cu
Oxidation
The loss of
electrons or
the addition
of oxygen
Cu --> Cu2+ + 2e-
Recycling
copper saves
money and
resources
It's cheaper to recycle copper
then it is to mine and extract
new copper from from its ore
Alloys
An alloy is a mixture of
a metal and other
elements
Steel is an alloy of iron
and carbon
Lots of things are made of steel
girders
bridges
engine parts
cutlery
washing machine
saucepans
ships
drill bits
cars
Brass, bronze, solder and
amalgam are also alloys
Brass
copper + zinc --> brass
Bronze
copper + tin --> bronze
Solder
lead + tin --> solder
Amalgam
contains mercury
Building Cars
Iron and steel corrode
much more than
aluminium
iron + oxygen + water --> hydrated iron (III) oxide
Aluminium doesn't
corrode when it's wet
When aluminium reacts
with oxygen it forms
aluminium oxide.
A protective layer of aluminium oxide
sticks to the aluminium below and stops
any further reaction taking place
Car bodies
Aluminium has two big advantages over steel
It has a
lower
density so
it is lighter
Aluminium corrodes less
and so and it has a longer
life time
You need
various
materials
to build
different
bits of a
car
Steel
Bodywork
Aluminium
engine parts
Glass
Windscreen and windows
Plastics
Internal
covering for
doors and
dashboards
covering
electrical
wires
Fibres
Seats and
flooring
Recycling cars is important
It saves...
natural resources
money
landfill
sight
size
85% (rising to
95%) of scrap
metal from
cars is
recycled
Acids and Bases
An indicator is a dye
that changes colour
The dye in the
indicator
changes colour
depending on
the pH of a
substance
Universal
indicator is a
combination of
dyes. It changes
colour
gradually as the
pH changes
Some indicators change
colour suddenly at a
particular pH
Phenolphthalein
changes suddenly
from colourless
to pink as the pH
rises above 8
The pH scale
Acids and bases neutralise each other
Acids form
H+ ions in
water
Alkalies
form OH-
ions in
water
acid + base --> salt + water
H+ + OH- --> H2O
Reactions
Metal oxides and metal hydroxides are bases
Acid + Metal Oxide --> Salt + Water
Acid + Metal Hydroxide --> Salt + Water
Acids and carbonates produce carbon dioxide
Acid + Carbonates --> Salt +
Water + Carbon Dioxide
Acids and ammonia produce ammonium salts
Acid + Ammonia --> Ammonium salt
Fertilisers
Fertilisers provide plants
with the essential for
growth
Fertilisers contain nitrogen,
phosphorus and potassium
If plants don't got enough of
these elements, their growth
and life processes are affected
Fertilisers are really useful-but they can cause big problems
Fertilisers damage lakes and rivers-eutrophication
When rain washes fertiliser
runs of the plants into rivers
and lakes
Algae in the water multiply rapidly
creating an algae bloom. This blocks
of light to the river parts and kills
them as they can't photosynthesise
Aerobic bacteria feeds
on the plant and
multiply. This uses up all
the oxygen
Because of this everything in the water dies
Preparing Fertilisers
Preparing fertiliser in the lab
Synthetic fertilisers are prepared in the lab by the reaction of an acid with an alkali. A quantity of
alkali is placed in a beaker and a solution of acid is run in until the solution is neutral. This can be
measured with a pH meter or by removing samples for testing with universal indicator.
The neutral solution of salt is evaporated until crystals form.
These are filtered out, washed and dried in a warm oven.
Percentage yield compares actual with predicted yield
Percentage yield is always between 0 and 100%
100% yield means that you got all the product you expected to get
0% yield means that no product was made
The Haber Process
The haber process is a reversible reaction
N2 + 3H2 --> 2NH3
Pressure : High (200 atmospheres)
Temperature : 450'C
Catalyst : Iron
The Haber Process
The iron catalyst
speeds up the reaction
and keeps costs down
Without the
catalyst the
temperature would
have to be raised
even further to get
a quick enough
reaction
Minimising the costs of production
Production cost depends on
several different factors