Simple Chemistry Experiment
Name: Marie H.
What simple, safe compounds might I have students (11-12
year olds) combine to observe a "dramatic or flashy" chemical reaction
other than with materials such as salt, vinegar, baking soda, etc? I
have 38 students in a lab and am stuck on issues such as safety and lack
of chemicals. Any suggestions? We have just finished elements and are
moving toward compounds and chemical reactions.
Any ideas on flame testing that I could do as demo for large group?
Assuming you have access to a Bunsen burner ...
Find someone who has an ordinary bench grinder that he/she uses to sharpen
chisels, drills, mower blades and the like. Collect the steel filings that are
near the grinding wheel -- or just purchase some very fine iron filings from a
scientific supply house.
Light the burner and then (from about a foot above) sprinkle the filings
sparingly in the flame. You will see a very pretty shower of sparks as the
burns and becomes iron oxide. The finer the filings, the prettier the show.
You can then explain to the students that fireworks sparklers contain metal
filings the burn to form all those pretty sparks.
The oxidation process occurring in the flame is much the same as that which
occurs when steel (mostly iron) rusts -- except "rusting" takes a lot longer
for the process to be completed. The flame simply hurries the oxidation
reaction to completion.
Next, wrap a magnet in a paper towel* and demonstrate that before the steel
filings are sprinkled in the flame, they are attracted to a magnet. Once
burned to iron oxide, the material is no longer attracted to the magnet. You
can prove this by attempting to pick up the material that has fallen through
the flame onto the desktop. Particles that are attracted to the magnet are
unreacted metal. You will discover some particles that are not attracted --
those are iron oxide.
* Why the paper towel? To keep the magnet clean and free of steel whiskers
that are difficult to pick off.
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Update: June 2012