If you walk into a room crowded with other people, you don't lose your identity; you stay the person you are. Sand and iron are the same. Add iron filings to sand or sand to iron filings and neither loses its identity. Preservation of identity is the key to a physical mixture. It is also a key to the separation techniques most useful for separating the components of a physical mixture. The techniques focus on a characteristic of one component of the mixture that another component does not share. In the case of a mixture of iron filings and sand, your separation technique uses the metallic character of iron to separate it from non-metallic sand.
- Shallow plastic tray
- Bar magnet
- Plastic wrap or a plastic sandwich bag
- Rubber bands
- Plastic bowl
- Sand
- Iron filings
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Instructions
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1
Spread a mixture of sand and iron filings thinly across a shallow plastic tray.
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2
Cover a bar magnet with one thickness of plastic wrap or a plastic sandwich bag. Use rubber bands to hold the plastic in place.
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3
Sweep the covered bar magnet over the scattered sand-and-iron mixture, allowing the iron filings to be attracted to the magnet.
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4
Hold the bar magnet over a plastic bowl. Remove the rubber bands and pull the plastic wrap from the magnet, allowing the iron filings to fall into the bowl as the force of magnetic attraction holding them to the magnet is interrupted.
