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Metals
How to distinguish common metals
1) Identify metals by color
The majority of metals have a gray color with shades that are difficult to distinguish.
However, there are two metals that have a characteristic color :
- Gold ( yellow )
- Copper ( orange-red )
2) Behavior of a metal in presence of a magnet
A magnet, placed close to several metals, only attracts iron
A magnetic test can therefore detect the iron among other metals.
Comments:
- In a recycling center the iron can be separated from other metals using magnets.
- A magnet can also attract an alloy containing some iron like steel or cast iron.
3) The density of metals
The density of a solid or a liquid can be calculated with the following relationship:
d = m
V
Where d is density ( no unity ), m is mass ( in kilogramme ) and V is volume (in liters orcubic decimeter )
Each pure metal has its own density that can be therefore used to identify it.
Example: The density of an object made of pure aluminum is always 2,7 regardless of its size and its shape. Furthermore if the density of an unknown metal is 2.7 then this metal is pure aluminium.
Density of common metals:
Aluminum: d = 2.7
Zinc: d = 7.1
iron: d = 7.3
Copper: d = 8.9
Silver: d = 10.5
Or: d = 19.2
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