Rocks and Metals

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Rocks and Metals
W Richards The Weald School
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Chemical formulae
The chemical formulae of a molecule or compound
is simply a way of showing the ratio of atoms in
it. For example
sodium chloride (NaCl)
potassium iodide (KI)
potassium nitrate (KNO3)
K
N
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Chemical formulae

• Try drawing these
• Water H2O
• Carbon dioxide CO2
• Calcium sulphate CaSO4
• Magnesium hydroxide Mg(OH)2

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Naming compounds
Rule 1 If two identical elements combine then
the name doesnt change
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Naming compounds
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Naming compounds

1. Potassium hydrogen oxygen
2. Lithium hydrogen oxygen
3. Calcium hydrogen oxygen
4. Mg(OH)2

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Naming compounds
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Simple formulae to learn
H2O CO2 NH3 H2 O2 N2 SO2
Water Carbon dioxide Ammonia Hydrogen Oxygen Nitro
gen Sulphur dioxide
NaCl CCl2 MgO HCl NaOH Ca(OH)2 CaCO3
Sodium chloride Calcium chloride Magnesium
oxide Hydrochloric acid Sodium hydroxide Calcium
hydroxide Calcium carbonate
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Simple chemical reactions
Water
H2O
Magnesium sulphate
MgSO4
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Balancing equations
Consider the following reaction


This equation doesnt balance there are 2
hydrogen atoms on the left hand side (the
reactants and 3 on the right hand side (the
products)
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Balancing equations
We need to balance the equation


Now the equation is balanced, and we can write it
as
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Some examples
2 2 2 3
2 2 2 2 3
2 2 2 2 2 4
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Paint
Paint is a mixture of different materials

1. A pigment a finely powdered ______ that has a
   strong ______
2. A binding medium an oil that sticks the _______
   to the surface
3. A solvent dissolves the binding medium and
   makes the surface easier to _____

When paint dries the solvent ______ away. In
emulsions the solvent is water whereas in gloss
paint the solvent is ____.
Words oil, coat, solid, colour, pigment,
evaporates
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Special Pigments
Thermocromic pigments
Phosphorescent pigments
Hi
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Limestone
Limestone is a __________ rock made up of mainly
calcium carbonate. Its cheap and easy to
obtain. Some uses
1) Building materials limestone can be
quarried and cut into blocks to be used in
_______. However, it is badly affected by ____
____.
2) Cement making limestone can be roasted in
a rotary kiln to produce dry cement. Its then
mixed with ____ and gravel to make _______.
Words sand, building, sedimentary, concrete,
acid rain
Thermal decomposition of limestone
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Composite Materials
A composite material is a material made of a
mixture of two different materials so that you
get the advantages of each, for example, a
reinforced wall
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The Structure of the Earth
Scientists have learnt this by studying seismic
waves (earthquakes)
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Movement of the Lithosphere
The Earths LITHOSPHERE (i.e. the _______) is
split up into different sections called ________
plates
Words radioactive, crust, convection, tectonic,
year
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Plate Movements
Magma
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Igneous Rock
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More on Plate Movements
Thick, less dense continental plate
Thin, dense oceanic plate
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Continental Drift
Look at the coastlines of South America and
Africa. I wonder of they used to fit together
Alfred Wegener
Im going to call this my Theory of Continental
Drift
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Tectonic theory

• Whats my evidence for this? Three things
• The jigsaw fit
• Each continent has similar rocks and fossils
• Each continent has similar animal species

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Another Example of Continental Drift
The formation of mountain ranges can be explained
by tectonic theory. Consider the Himalayas at
the top of India
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Copper and Aluminium
Metal Uses and why Extraction method Problems
Copper Electrical wires good conductor Electrolysis Limited supply
Aluminium Planes light and corrrosion resistant Complicated and expensive Expensive and difficult to extract
Supplies of any raw material are limited so what
are the options?
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Purifying Copper
Solution containing copper ions
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Alloys
Steel is an alloy i.e. a mixture of metals.
Here are other alloys
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Smart Alloys
A smart alloy is one that can remember its
original state after being bent or stretched.
These glasses are made from a smart material
if they are bent they will return to their
original shape
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Rusting
Task To investigate what causes rusting
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Rusting
Task To investigate what causes rusting
No rust
No rust
Rust
Lots of rust
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Materials in a Car
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Iron or aluminium?
Aluminium
Does not corrode Less dense so its lighter
Iron
Cheaper than aluminium Magnetic so easily recycled
Most cars are made from steel (an alloy of carbon)
From 2015 95 of a car will have to be made from
recylced material. What are the advantages of
this?
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Recycling
Why recycle?

1. Less space will be needed for landfill sites
2. Recycled metals only need about 1/10th of the
   energy to produce compared to producing new
   metals
3. Recycling paper reduces the amount of water and
   energy needed to produce it
4. Recycled glass only needs 80 of the energy to
   produce compared to producing new glass
5. Recycling saves on raw materials
6. Less excavation and mining costs

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Evolution of the Earths Atmosphere
Present day atmosphere contains 78 nitrogen, 21
oxygen, 1 noble gases and about 0.03 CO2
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Evolution of the Earths Atmosphere
Some of the oxygen is converted into ozone. The
ozone layer blocks out harmful ultra-violet rays
which allows for the development of new life.
Animals now take in the oxygen produced by plants
and give out carbon dioxide (respiration).
Plants take in this carbon dioxide and give out
oxygen (photosynthesis).
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Air Pollution
NO, NO2 and CO
These gases produce acid rain (which affects
tress and buildings) and worsens the greenhouse
effect
Power stations produce CO2, SO2 and NO2
Cars produce NO, NO2, CO and smog
One way to reduce car pollution is to use a
catalytic converter. These devices convert
harmful carbon monoxide into less harmful carbon
dioxide
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Carbon dioxide in the atmosphere
The amount of CO2 in the atmosphere has been
affected by a number of things
1) When fossil fuels are burned the carbon
contained in them reacts with oxygento form CO2.
2) Deforestation is removing many of the trees
we need to convert carbon dioxide into oxygen
3) The increase in world population is making
both of these much worse
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Rates of Reaction
Oh no! Here comes another one and its got more
energy
No effect! It didnt have enough energy!
Here comes another one. Look at how slow its
going
Hi. Im Mike Marble. Im about to have some
acid poured onto me. Lets see what happens
It missed!
Here comes an acid particle
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Rates of Reaction
View animation
Words activation, quicker, catalyst,
temperature, collide
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Measuring the Rate of Reaction
Two common methods
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Rate of reaction graph
Amount of product formed/ reactant used up
Time
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Rate of reaction graph
Q. What if less reactants were used?
Amount of product formed/ reactant used up
Time
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Calculating the Rate of Reaction
Rate of reaction the gradient of the graph
20cm3
Amount of product formed/ reactant used up
Rate of reaction 2cm3/s
10s
Time