Activity 6
Which can is which?
Recycling
Context
The average Australian consumes 6 kilograms of drink cans per year. That’s more than 1.7 billion cans a year and
only around 56% of them are recycled across Australia.
Recycling cans makes sense. Some cans are made from aluminium and others from steel.
Steel is an alloy made from iron and carbon that takes a lot of energy to create. It’s 100% recyclable and recycled
steel uses 75% less energy to make than steel from raw materials. Every tonne of recycled steel saves 1131kg of
iron ore, 663kg of coal and 54kg of limestone.
Aluminium is made from bauxite and requires a great deal of energy, water and resources to make. Making
recycled aluminium uses up to 95% less energy, and saves water and resources too.
Aluminium is 100% recyclable. Aluminium drinking cans are the most recycled packaging product in the world.
All statistics from the Steel and Aluminium Fact Sheet, www.cleanup.org.au
Resources required
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3 similarly sized empty cans labelled #1, #2, #3: (1=aluminium, 2=steel, 3=bi-metal)
for each station (snack-sized fruit cans are often bi-metal)
magnet and magnetic compass
scales
bucket of water and a bucket of ice
stopwatch
magnifying glass
two jars (with lids) labelled ‘Aluminium nails’ and ‘Steel nails’
aluminium nails and steel nails
matches
candle in candle holder
rubber-handled pliers
small amount of candle or sealing wax
tweezers
steel wool and alfoil
beakers with paper lid
thermometer
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Activity 6
Which can is which?
Recycling
What to do
Students can either conduct each of the following experiments by rotating through a series of stations or be
allocated an activity to report back to the class.
1.Comparison by appearance
Describe each can’s appearance. What makes them similar, what makes them different? Consider texture, colour
and how shiny or dull they are, recycling symbols and even the types of rims.
2.Comparison by magnetism
Use the magnet to determine which cans are magnetic. Does the can make the compass needle move? How
does this relate to magnetism?
3.Comparison by weight
How much does each can weigh? Weigh each can on the scale.
4.Comparison by floatation
Try to float each can by putting it on its side in the bucket of water. Record if the can sinks immediately; record
how long it takes for it to sink if it does float initially. This means recording how long it takes for the water to fill the
can which will then make it sink.
5.Comparison by resistance to corrosion
Place two aluminium nails (or alfoil) into the jar labelled ‘Aluminium nails’ and sprinkle with water. Place two steel
nails (or steel wool) into the jar labelled ‘Steel nails’ and sprinkle with water. Leave for 4–5 days, then check each
jar and record which nails have rust and which appear to have resisted corrosion.
6.Comparison by temperature conductivity (heat) - Requires supervision by an adult
A.Break off two pieces of wax, each about the size of a pencil eraser.
B.Using tweezers, hold each piece of wax in a candle flame until soft. Attach one piece of wax to the middle of an
aluminium nail and one to a steel nail.
C.Assign one student to be the timekeeper. Light the candle.
D.Holding one end of nail 1 (aluminium) with the pliers, place the other end of the nail in the candle flame. Have
the timekeeper time how long it takes for the wax to melt.
E.Repeat the experiment with nail 2 (steel). On which nail did the wax melt faster?
7.Comparison using temperature conductivity (cold)
A.Fill the 3 cans halfway with water
B.Assign a different student to be the timekeeper.
C.Measure the temperature of the water in each can (they should all be room temperature).
D.Place each can in the bucket of ice. Measure the temperature of the water in each can at 1 and 2 minute
intervals for about 5–10 minutes. Record the temperature of each can’s water.
E.The water in which can cooled the fastest or the most?
Compare the cooling experiment with the heat conduction experiment. Did the can which cooled the most also
heat the fastest?
Alternative experiment 5
1.Place a piece of steel wo
ol in one beaker and a pie
ce of alfoil in another.
2.Pour vinegar on each and
leave for around 1 minute
to soak in. Drain off any exc
vinegar.
ess
3.Wrap the soaked steel wo
ol around the base of one
thermometer and place in
beaker. Wrap the soaked alfo
a clean
il around another thermome
ter and place in a different
clean beaker.
4.Cover the beakers with
paper or a lid to keep the hea
t in (make sure you can stil
the temperature on the the
l read
rmometer; you can make a
small hole in the
paper or lid for the thermo
meter to go through).
5.Check the initial temper
ature of each and then mo
nitor for
around 5 minutes.
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Activity 6
Which can is which?
Recycling
Teaching background
el wool should
ide the beaker with ste
ins
ure
rat
pe
tem
the
5,
ent
beaker.
For alternative experim
ensing on the side of the
en notice moisture cond
ev
t
iron in the
gh
the
mi
u
ws
yo
allo
e;
d
ris
gradually
tive coating an
tec
pro
its
es
ov
rem
ar
in vineg
form of heat)
Soaking the steel wool
(releases energy in the
ic
erm
oth
ex
an
is
n)
oxidatio
so the
resistant to corrosion
steel to rust. Rusting (or
oxygen. Aluminium is
d
an
n
iro
en
twe
be
n
chemical reactio
e.
temperature will not ris
d drink packaging:
m and steel for food an
niu
mi
alu
of
s
rtie
pe
has a
Comparison of the pro
cm); iron used in steel
t (density 2.70g/cubic
ligh
ry
ve
e, ship,
are
an
(pl
cts
du
en
nsport chos
• Aluminium pro
n affect the type of tra
ca
t
igh
We
.
cm
bic
/cu
density of 7.86g
rtation costs.
train, truck) and transpo
n iron.
heat 2.4 times faster tha
• Aluminium transfers
making aluminium
ly
ick
qu
and gained very
t
los
is
at
he
e
for
ere
Th
a cold drink container.
ideal for cooking and as
d cast and joined,
o extremely thin foil an
int
led
rol
be
n
ca
m
niu
• Alumi
its strength.
and still retain much of
Analysing the results
Once the tests have all been conducted put the data into the table on the student worksheet.
Students decide how their data could be depicted and then create a presentation.
Follow up activities
As an individual student, team or a whole class, create a list of the pros and cons of different metals for cans.
Write a riddle or who am I to show the properties of the different types of cans. Here’s an example:
What can am I?
I am not magnetic
I am the lightest of the three cans
I am the greatest conductor of heat (so I chill and heat up the fastest)
Aluminium
I am magnetic
I am the heaviest
I conduct heat slowly and chill slowly too
Steel
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Activity 6
Which can is which?
Recycling
Further activities
1. What would be the mo
st efficient way to sort ste
el cans from aluminium
Explain your choice.
cans?
2. Why do you think bever
ages are generally placed
in aluminium cans rathe
in steel cans?
r than
3. Which products would
be suitable for steel can
s? For bi-metal cans?
4. Why choose a can at
all? Compare the prope
rties of cans to the prope
packaging materials.
rties of other
5. Design and conduct an
experiment to compare
the properties of glass
and plastic bottles. Co
nduct an experiment to
compare the properties
paper, cardboard and
of
liquid paperboard. Presen
t your findings in table
form. Comment on the
suitability of each for a ran
ge of packaging.
What is a bi-metal can?
Bi-metal refers to cans that are composed of two separate metals, in
this case, aluminium and steel, joined together. Bi-metal cans are not a
mixture of two or more metals, like alloys, but rather layers of different
metals.
Trimetal and tetrametal refer to objects composed of three and four
separate metals respectively.
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Activity 6
Which can is which?
Recycling
Student WORKSHEET
Comparison by
appearance
Aluminium
Steel
Bi-metal
Aluminium
Steel
Bi-metal
Aluminium
Steel
Bi-metal
Aluminium
Steel
Bi-metal
Texture?
Colour?
Shiny or dull?
Rims?
Recycling symbol?
Comparison by
magnetism
Did the magnet attach?
YES/NO
Did the needle of the
magnetic compass move?
YES/NO
Comparison by
weight
In grams
Comparison by
flotation
Floats immediately
YES/NO
Time to sink
Capacity of can in mLs
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Which can is which?
Activity 6
Comparison by
resistance to corrosion
Recycling
Aluminium (foil or nails)
Steel (wool or nails)
Aluminium (foil or nails)
Steel (wool or nails)
Aluminium nail
Steel nail
Description after one week with water
Comparison by
resistance to corrosion
Temperature initially before vinegar in
beakers
Temperature in beakers after 5 minutes
Temperature in beakers after 10
minutes
Comparison by
temperature conductivity
(heat)
Time in seconds for the wax to melt
Comparison by
temperature
conductivity (cool)
Aluminium
Steel
Initial temperature of the
water in cans (should be the
same)
Temperature in can after 1
minute
Temperature in can after 2
minutes
Temperature in can after 3
minutes
Temperature in can after 4
minutes
Temperature in can after 5
minutes
56 | Recycle Right is a program delivered by Zero Waste SA www.zerowaste.sa.gov.au
Bi-metal
Activity 6
Which can is which?
Recycling
Analyse your RESULTS
Comparing aluminium
and steel
Aluminium
Steel
Appearance (similarities)
Appearance (differences)
Magnetic (YES/NO)
Weight (heavier or lighter)
Floats (YES/NO)
Resistant to corrosion (YES/NO)
Conducts temp – heat (YES/NO)
Conducts temp – cool (YES/NO)
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