Copper is the most abundant and active member of the Nobel Metals; copper,
silver and gold. It is used in many applications in our society the most notably being the
use as an electrical conductor; your home, cell phone, calculator, etc. are wired with
copper! But, Copper compounds can cause problems! “In animals, inhalation of copper
dust has caused hemolysis of the red blood cells, deposition of hemofuscin in the liver
and pancreas, and injury to the lung cells; injection of the dust has caused cirrhosis of the
liver and pancreas, and a condition closely resembling hemochromatosis or bronzed
diabetes. (Sax, Dangerous Properties of Industrial Materials, eighth edition) that means
that copper is like other heavy metals, it can be bad for your health if you aren’t careful!
Iodine is, on the other hand, is the least haziest of the halogens. “It is a solid at
room temperature. It exists in bluish-black plates with a rhombic shape, metallic luster,
and peculiar order. Iodine is a non-metallic element, existing in sea-water and sea-plants.
When it is dissolved in alcohol, it is called a tincture. That solution can be used as a very
effective disinfectant. But, since it does kill things, if it is used as a disinfectant, it will
cause scaring. There are other problems too.
Copper iodide is used in the production of some organic compounds, as a cloud
seeding compound, and to help stabilize nylon used in high temperature applications.
Gee, this is a lot of good to know info, isn’t it? Well let’s get back to the lab and think
what we are going to do today!
At times, we are fortunate enough to observe a chemical reaction that is easy to
control and involves chemicals that can be easily handled. We can use this type of
reaction to collect quantitatively data to confirm concepts that are under consideration in
the high school setting. One such reaction is the reaction between copper and iodine.
You will remember that during your introductory chemistry experience, you submerged a
copper wire into a solution of iodine. The color of the copper changed indicating a
chemical reaction. If we are careful and measure the mass of copper before the reaction,
the mass of the copper with the product on it, and then dissolve the product and re-mass
the copper, we should be able to determine the formula of the copper-iodine compound.
Since copper has two oxidation states (charges), you will be able to determine if the
compound is CuI or CuI2; we will be able to determine the empirical formula of copper
iodide. Let’s do some chemistry!