Teacher Preparation Notes for Metal Identification Lab
Background:
Many methods are used to identify a piece of metal. Some common methods used
for field identification are surface appearance, chemical tests, and the use of a
magnet. Sometimes it is possible to identify metals by their surface appearance.
Copper and copper alloys will have an orange-brown or yellowish appearance, while
tin, aluminum, iron, and zinc will have a dull or shiny gray-silver surface.
When the surface appearance of a metal does not give enough information to allow
positive identification, other identification tests must be done to identify the
metal. All metals can be placed into two groups --- ferrous or nonferrous. Ferrous
metals are magnetic and include iron. Other metals are nonferrous.
Reaction with strong acids such as hydrochloric acid can be used for metal
identification. Zinc reacts immediately and violent with HCl. Tin shows little or no
reaction with HCl, and aluminum has a delayed reaction with HCl.
Data Table:
Metal
Aluminum
Copper
Appearance
Gray, dull,
sometimes
shiny
Yellow to
orange-brown
Magnetic
HCl
No
Delayed
reaction
No
No reaction
Iron
Dark
Yes
Delayed
reaction
Tin
Dull,
yellowish
metal
No
Little, if nay
reaction
Zinc
Shiny, Dense
(heavy) metal
No
Immediate
violent
reaction
Time:
Teacher preparation – 20 minutes
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Class time – 45 minutes
Materials:




Samples of metals (iron, aluminum, tin, zinc, and copper)
2- 250 ml beakers (per lab group)
Disposable dropper (one per group)
HCl
Student Safety Issues:
Review students on proper dress for lab --- aprons, goggles, and gloves. Also
review students on location of sinks and eye washes for flushing off chemicals and
the care and use of acids.
Disposal of Materials:
Hydrochloric acid may be poured down the sink and flushed with excess water.
Hint:
Set up all lab supplies the day before lab on a lab cart or an area of the lab
accessible to all students.
Answer to Questions:
2
COLOR
YELLOW to
ORANGE-BROWN
NOT Yellowish
MAGNETIC
YES
COPPER or
COPPER
ALLOY
IRON or IRON
ALLOY
NO
REACT WITH
ACID
FAST?
NO
NO
TIN
1.
2. a. copper
ZINC
ALUMINUM
b. iron
References:
Metals color test –
http://www.muggyweld.com/colortest.html
Metal Identification http://www.tpub.com/content/construction/14250/css/14250_21.htm
Metal Properties –
http://www.angelfire.com/my/welding/metal.html
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