Download The production and use of metals

The production and use of metals
How can we make metals?
Can we use the same method for all metals?
Name ____________________________
Class
__________
Date
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Teacher
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ADDITIONAL BOOKLET 3
1
THE PRODUCTION AND USE OF METALS
You should:
Tick
Examine the relationship between the method of extraction
of a metal from its ore and its position in the reactivity
series (e.g. aluminium, a reactive metal is extracted by
electrolysis; iron, a less reactive metal, by chemical
reduction)
Use displacement and competition reactions of metals to
determine their relative reactivity
Explain the term reduction (removal of oxygen) and oxidation
(gain of oxygen) and recognise their occurrence in reactions
Know that the extraction of a metal requires the process of
reduction
Know the meaning of the terms electrolysis, electrode, anode,
cathode and electrolyte
Know the processes involved in the commercial extraction of
aluminium , including being able to write and interpret word and
balanced symbol equations for the reactions at the anode and
the cathode
Know the reasons for the high cost of the process and how
these costs are minimised
Know that recycling aluminium uses only about 5% of the energy
needed to extract it from bauxite and saves waste
Discuss the factors affecting the siting of an aluminium
extraction plant
Relate the uses of aluminium, copper and titanium to their
properties
Relate the uses of different steels to their composition and
properties
Know that steel is recycled on a large scale and that recycling
steel saves 50% of the energy used in the extraction of iron,
helps to conserve iron ore and also cuts down on the emission of
greenhouse gases
Evaluate the social, economic and environmental impact of the
use and extraction of metals
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Summary Sheet
The reactivity series
This booklet is all about metals. Some metals are more reactive than
others. We can list them in order of their reactivity as follows;
Displacement/competition reactions –
often used to extract metals.
A reactive metal can displace a less reactive metal from its compound. As
an example, you saw a displacement reaction (the thermite
reaction/Brainiac video) in core booklet 3. The thermite reaction is;
Aluminium + iron oxide
aluminium oxide + iron
In this reaction aluminium is more reactive than iron. It therefore
DISPLACES it from its oxide. It REDUCES the iron oxide.
Extracting
aluminium.
metals
from
the
ground;
This is a picture of a gold mine (which looks
much better in colour). Gold is an
unreactive metal which means that it’s
stable on its own. Because of this it is
relatively easy to extract.
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examples
gold,
iron
and
The more reactive a metal, the more stable are it’s compounds and
therefore the more difficult they are to extract.
Iron is a fairly reactive metal. It is found as an ore called haematite
which is mainly iron oxide mixed with impurities. Iron is extracted in the
Blast Furnace (Port Talbot Steelworks) using more reactive carbon to
displace it. The carbon removes the oxygen from the iron. This is known
as REDUCTION. Once extracted, the excess carbon is removed from
the ‘pig’ iron forming steel. Steel is basically an alloy of iron and carbon
although many other metals can be added to make many different types
of steel. Here are some examples;
Steel type
Mild
% Carbon
< 0.5%
Medium
0.5% – 1%
High Carbon
>1%
Uses
Bendable in thin sheets.
Used for car bodies,
food cans.
Harder,
used
for
hammer, axe heads
Harder still but not as
strong, used for scissors,
knife blades, drill bits.
Manganese steel is an alloy of iron (84%), manganese (15%) and carbon (1%).
Manganese steel is extremely hard and is used for railroad switches and
dredging equipment.
Stainless steel is an alloy of iron (80%), chromium (15%), nickel (4%) and carbon
(0.5 to 1%).
Stainless steel is strong and hard, with a very high resistance to corrosion (due
to chromium).
It is used for cookware, cutlery and industrial chemical plant.
Aluminium is a reactive metal. It is found as an ore called bauxite which
is mainly aluminium oxide mixed with impurities. Aluminium is difficult to
extract. The extraction process is known as electrolysis which is
expensive and not particularly environmentally friendly.
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Using electrolysis to reduce aluminium oxide and therefore produce
aluminium.
1. the aluminium oxide has to be molten so that it splits into
mobile ions Al3+ and O2-. This takes enormous amounts of
energy. Aluminium oxide is an ionic compound. Because of its
giant lattice structure it has a very high melting point (efforts
to reduce the melting point of aluminium oxide are made by
adding it to a substance called cryolite)
2. The molten aluminium oxide is now a liquid that can conduct
electricity. It is known as an electrolyte.
3. The electrical current is switched on.
4. Al3+ ions attract to the negatively charged lining (the cathode
electrode). At this point electrons moving out of the cathode
are donated to the Al3+ ions so that aluminium atoms form.
Voila! We have the aluminium.
Al3+ + 3e
Al
5. In the meantime the oxygen ions have attracted to the
positively charged electrode (the anode). Here they have their
excess electrons removed turning ions back into molecules.
2O2- - 4e
O2
6. As oxygen forms at such high temperatures it actually reacts
with the anode. The anode has to be replaced every so often.
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Siting an aluminium extraction plant - site requirements include a source
of cheap electricity, deep water facilities for the importation of raw
materials and good road and rail communications. A site would also;
require a large amount of open flat land, need to be near to a
workforce but far away from local communities so that pollution issues
were minimised.
Environmental issues involved in the extraction of metals.
The extraction of iron and aluminium are carried out at extremely high
temperatures. Heat energy is created through the combustion of fossil
fuels which as we know from core booklet 6a result in the formation of
carbon dioxide. Carbon dioxide in turn contributes to global warming.
Sulphur and nitrous oxides are also created during fossil fuel
combustion these gases dissolve in water to form acid rain.
In order to produce aluminium electricity is required.
Creating
electricity also involves the combustion of large amounts of fossil fuels
which of course are non-renewable. Open cast mining to obtain metal
ores results in scarring of landscapes and disruption to animal and plant
habitats.
Social and economic issues involved in the extraction of metals
Take Port Talbot as an example. Port Talbot was an ideal site for the
steelworks that remain there today because of its deep water port,
access to coal (carbon) needed to reduce the iron oxide, open flat land
and good transport links. Sandfields was built to house an influx of new
workers and local businesses prospered.
Port Talbot Steelworks
attracted a great deal of investment into the area including the
establishment of a chemical plant at Baglan by British Petroleum.
Port Talbot Steelworks brought more money, more jobs and therefore
more workers into the Port Talbot area as a result, more schools and
more houses were built. Over the years as the chemical plant has shut
down and steel production has decreased however, also because of
pollution, economic prosperity has declined in the area and people
have started to move away.
The uses and properties of aluminium, copper and titanium.
A property of a metal is how it behaves, for example it might be very
strong, a good conductor of heat or electricity. Depending upon their
properties, metals are used for different things, here are some examples.
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Metal
Titanium
Use
Hip replacement
Property
Non-toxic, extremely
strong
tennis rackets, golf Light,
extremely
clubs
strong
Metal
sheathing Attractive colouring
around buildings e.g.
the
Guggenheim
museum in Bilbao in
Spain.
Copper
Electrical cables
Good conductor of
electricity
Copper pipes
Resistant to corrosion,
waterproof
In
cookware
e.g. Attractive appearance,
good conductor of heat.
saucepans
Aluminium
Food wrapping
Non-toxic,
impermeable
Aircraft
Lightweight
Mirrors
Excellent
reflective
properties.
Recycling metals such as iron and aluminium
The disadvantages of extracting metal such as iron and aluminium are as
follows:
1. Enormous amounts of energy are required resulting in the
combustion of non-renewable fossil fuels.
2. During the combustion of fossil fuels large amounts of greenhouse
gases are produced contributing to global warming.
3. CO2, NOX and SO2 produced during combustion cause acid rain.
4. Large areas of land are destroyed by open cast mining to obtain
the ores.
5. Mining affects plant and animal habitats.
One solution to these problems is to recycle rather than extract
these metals. Recycling aluminium uses only about 5% of the energy
needed to extract it from bauxite and saves waste. Steel is recycled
on a large scale and which saves 50% of the energy used in its
extraction. Recycling also helps to conserve iron and aluminium ore
and also cuts down on the emission of greenhouse gases.
END OF SUMMARY SHEETS
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DISPLACEMENT/COMPETITION REACTIONS
Metals are able to displace less reactive metals from their
compounds in what are called DISPLACEMENT reactions,
sometimes known as competition reactions.
 We can use displacement reactions to work out the
reactivity series for metals.
 We can use the reactivity series of metals to PREDICT
the outcome of a reaction.
Class Prac – the displacement
reactions of metals
In this experiment you will be looking at the reactions between
various metals and metal salt solutions.
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Procedure
1. Take the plastic covered worksheet.
2. Place a copper turning in each box in the copper row.
3. Place one small piece of magnesium ribbon in each box in the
magnesium row.
4. Place a few zinc granules in each box in the zinc row.
5. Place an iron nail in each box in the iron row.
When all the pieces of metal are in place:7. Add two drops of copper sulphate to each metal in the first column.
Observe and record your observations.
8. Add two drops of iron nitrate to each metal in the second column.
Observe and record.
9. Add two drops of magnesium nitrate to each metal in the third column.
Observe and record.
10. Finally, add two drops of zinc chloride to each metal in the fourth
row. Observe and record.
Results
Copper
sulphate
solution
Iron(III)
nitrate
solution
Copper
Magnesium
Zinc
Iron
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Magnesium
nitrate
solution
Zinc
chloride
solution
Conclusion – using your results try to place your metals in order of
reactivity.
Increasing reactivity – put metals above arrow in correct order
Write out equations for each reaction.
simply write down no reaction.
Copper + Copper sulphate
Copper + Iron nitrate
Copper + Magnesium nitrate
Copper + Zinc chloride
Magnesium + Copper sulphate
Magnesium + Iron nitrate
Magnesium + magnesium nitrate
Magnesium + zinc chloride
Zinc + Copper sulphate
Zinc + Iron nitrate
Zinc + Magnesium nitrate
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If there was no reaction
Zinc + Zinc chloride
Iron + Copper sulphate
Iron + Iron nitrate
Iron + Magnesium nitrate
Iron + Zinc chloride
REDUCTION REACTIONS
Most metals are found as metal oxides. To extract them the
oxygen must be removed. A REDUCTION reaction is one in
which oxygen is removed/lost.
Watch the two teacher demos of reduction reactions. Write
down word equations for both of them, N.B. both of these reactions can also be
described as displacement reactions. Not only that, they are REDOX reactions because as the metal oxides
are reduced the magnesium/carbon are gaining the oxygen; they are being oxidised.
1. Magnesium + Copper Oxide
2. Carbon + Lead Oxide
Iron is removed from it’s oxide in the Blast Furnace by carbon
in the same way as lead was removed in teacher demo 2. Write out a word equation
for the reduction of iron oxide in the space below. Use
equation 2 above to help you. This reaction is also how man
discovered iron.
+
+
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K.S
communication
Read page 4 and answer the following questions on the
production of iron:
1. Iron is a fairly reactive metal. Which would be the easiest metal
to extract; a reactive or an unreactive metal?
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2. What is a reduction reaction?
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3. What is steel?
_____________________________________________
_____________________________________________
4. Look at the table of mild, medium and high carbon steels. Write a
sentence to describe the relationship between the % carbon and
the hardness of steel.
_____________________________________________
_____________________________________________
5. Look at the bottom of page 7. What are the advantages
of recycling steel?
_____________________________________________
_____________________________________________
6. Complete the table to show the composition, properties and uses of
manganese and stainless steel.
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The extraction of aluminium – another reduction reaction.
1.
Look at the laminated cartoon cards showing the electrolysis of
aluminium oxide. Put them into the correct order and draw them into
the boxes below.
1 During this process aluminium oxide is heated to
extreme temperatures so that its ions are free to move
around.
Al2O3(s)
heat
Al3+(l)
+
O2-(l)
Molten aluminium oxide now acts as a liquid that
conducts electricity – an electrolyte.
2 Electricity is passed through the molten
electrolyte via positive and negative electrodes.
As soon as the mobile ions are subjected to an
electrical charge they run to their opposite
electrodes
3 The positive aluminium ions are given their 3
valence electrons back by the cathode. They turn
back into atoms.
Al3+ + 3eAl(l)
4 The negative oxygen ions have their 2 valence
electrons taken off them by the anode. They turn
back into molecules.
2O2- - 4eO2(g)
5 Molten aluminium is tapped off from the bottom
of the electrolysis cell and rolled into ingots for
export elsewhere.
6 In the heat of electrolysis oxygen burns the
carbon electrode forming carbon dioxide gas. The
anodes thus have to be replaced from time to
time.
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2. Watch the short DVD of an aluminium extraction plant.
Write known any notes on the ‘notepad’ below:
3. Electrolysis is also used to purify metals and to copper
plate. Carry out a practical activity to copper plate a 1p
coin. Stick your coin over the top of this one. Not in exam!
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Debate - you are going to debate whether or not to site an
aluminium extraction plant at Llandarcy, the site of the B.P
oil refinery which closed there in 2000. In preparation for
the debate write down a list of advantages and
disadvantages that it would bring to the local area in the
spaces below.
Advantages
Disadvantages
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I.C.T – find
and present.
Copper, titanium and aluminium
Using the internet find out about the history (local if
possible), properties and uses of copper, titanium and
aluminium. Add in any other little facts; for example, did you
know that since the 1950’s there has been a titanium factory
called TIMET in Waunarlwydd. During the cold war they used
to make the titanium into parts to send nuclear bombs over to
Russia. Now they use it for Rolls Royce engine parts.
Relate the uses of these metals to their properties; for
example you might say that aluminium is used in food wrapping
because it’s non-toxic.
If you complete your research you can go onto Birchfield
Chemistry.
Staple your research onto the back of this booklet.
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KEY WORDS FROM BOOKLET
Extract
to remove a metal from its ore
Displacement Reaction
one in which a reactive element
removes a less reactive element
from its compound.
Reduction Reaction
one in which oxygen is removed
Reduce
to remove oxygen
Oxidation Reaction
one in which oxygen is gained
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Oxidise
to supply oxygen
REDOX reaction
one in which oxidation and
reduction occur at the same time
Physical property
how a substance behaves e.g it
could be a good conductor of heat
or electricity.
Iron
a fairly reactive metal element
extracted in the Blast Furnace.
Steel
an alloy of mainly iron and carbon.
Aluminium
an abundant reactive metal with
many useful properties extracted
from its oxide by electrolysis.
Electrolysis
a process that separates a metal
from a non-metal through the use
of electricity
Electrolyte
a liquid that is able to conduct
electricity
Anode
a positive electrode
Anion
a negative ion
Cathode
a negative electrode
Cation
a positive ion
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