| Everyday science |
| Why do some people
experience an electric shock when a metal spoon
touches their filled tooth? |
For a nerve-wracking
experience involving the oxidation of elemental
aluminum, bite a piece of aluminum foil with
a tooth filled with dental amalgam (used for
dental fillings). The aluminum behaves as an
anode and releases electrons to the amalgam
(a mix of silver, tin, and mercury). The amalgam
behaves as a cathode by transferring these electrons
to oxygen, which then combines with hydrogen
ions to form water. The slight current that
results produces a jolt of . . . ouch . . .
pain.
Why are decorative items plated with silver
or gold?
Silver and gold metals are expensive metals.
Some people desire to have silverwares in their
homes – utensils, spoons, forks, etc., or heavy
gold jewelry, as a mark of being fashionable
and having good taste. But these are expensive
to have them in pure silver. So a cheap metal
such as low-grade steel or iron is first made
into a desired object, say a spoon. Then these
items are coated with silver by electroplating.
Same is true about gold plated jewelries. |
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