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 Metals Information Sheet and Worksheet

*Activity based on Brumcan's Education Pack and reproduced with their kind permission. Please see the Other Resources and Contacts for Information Section for further details. Items in bold will need to be brought in from home.

Background information

There are many different metal objects found in household waste or items containing metals. This activity focuses in on tin plated steel cans and aluminium cans and foil. Tins or cans are either made from steel (which has been coated in tin plate to prevent corrosion) or aluminium. Food cans are predominantly made from tin-plated steel where as drinks cans are made from aluminium or steel. Sometimes the ends of the can are made from aluminium and the body of the can is steel. It is now common to find the recycling symbol and the abbreviation "alu" or the word "steel" on the sides of cans. Many crisp packets are made from a shiny plastic that looks like metal foil but is in fact plastic. In these activities the children will test and sort the materials on the basis of their magnetic and plastic qualities and compare aluminium with steel in a simple oxidation test.

Aluminium and steel cans are produced by different processes and the two metals posters illustrate this. In both cases recycling scrap metal takes a lot less energy than producing virgin metals from the raw materials. In the case of aluminium these energy savings are quite significant and the calculation in the extension activity is intended to illustrate this in terms that will be meaningful to the children.

Answers and notes

Activity 2         The nail is used to remove the tin plate or other coating material to let the steel be exposed to the salt water

Activity 3         Please ensure adequate supervision while making the holes in the cans

Extension Activity 1   Recycling Energy

This activity makes several assumptions about the amount of energy a 30kg person would use riding a bike. This figure has been derived from energy consumption data. This is not an exact measure but is intended to illustrate the significant energy savings achieved by recycling aluminium cans relative to making aluminium from bauxite. It is also not possible to exactly measure the energy needed to make one can's worth of aluminium - this figure has been derived from the energy used to make one tonne of aluminium from bauxite and dividing this by the number of cans in one tonne of aluminium.

Answers         Question 1 = 17 kJ

Question 2 = 50 minutes (c)

Question 3 = 42.5 kJ (b)

Question 4 = 2.5 minutes (c)

Question 5     The comparison is not very fair because the two processes are too different. The amount of energy expended by the cyclist will be a function of how fast they are pedalling, whether it is uphill or down, and how much the cyclist weighs as well as how fit they are.

Metals extension activity 1: recycling energy

Making metal uses energy. Riding a bike also uses energy. You are going to work out how long a person would need to ride a bike in order to use the same amount of energy as is needed to make aluminium cans.

To work it out you will need to use the following information.

Using bauxite to make aluminium uses about 850kJ (kilo Joules) to make one can.

If someone who weighs about 30kg, rides a bike for 10 minutes they use up about 170 kJ of energy.

1.         How many kilo Joules does the person use every minute?

170 kJ ÷ 10               Answer __________________________

2.         How long would this person need to ride their bike for to use the same amount of energy as is needed to make one can from bauxite? Use a calculator to work out this formula.

Energy needed to make a can ÷ energy used to ride a bike for one minute = number of minutes

a) 25 mins. b) 1hr 30 mins. c) 50 mins. Answer ___________________

3.         If the can were made from recycled aluminium it would need only 5% of the energy needed to make cans from bauxite.

How much energy would be needed to make a recycled can made from used cans? (5÷100) x 850

a) 60kJ b) 42.5 kJ c) 1000kJ         Answer ___________________

4.         How long would the person need to ride their bike to make this much energy?

Energy needed to make a recycled can ÷ energy used to ride a bike for one minute = number of minutes

a) 2 hours b) 6 minutes c) 2.5 minutes Answer ___________________

5.         Do you think that comparing the two uses of energy is fair and accurate? Are there any other things that you might need to take into account to make the calculations more accurate or more fair?

_______________________________________________________

Metals extension activity 1:
Can Recycling Game players instructions

To play this game you need to pretend to be aluminium cans using actions and sounds to show what is happening to you throughout your "life". You are out if you perform the wrong actions or if you don't perform the action. The winner is the last "can" left standing.

The teacher will call out certain words, each of which has an action. The first time is a practice round for you to get used to the actions.

After the practice round each time you hear the word you must perform the action or be out!

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