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Iodine I
Where is iodine used--or where does it impact our everyday lives?
Used as a disinfectant--can be used to disinfect the skin before a shot/vaccination
A dietary requirement--needed for the functioning of the thyroid gland in the neck
Iodine is added to some table salt to ensure sufficient iodine intake.
Iodine is a halogen, in group 17 (7) of the Periodic Table. It is a solid at room temperature with a flaky, metallic look.
Halogen is the name given to Group 17 (7) in the periodic table. Fluorine, F, chlorine, Cl, bromine, Br, iodine, I, and astatine, At are the halogen elements. Halogen light bulbs are made with iodine or bromine. The halogen vaporizes in the bulb when it heats up and the loss of tungsten atoms from the wire filament is significantly reduced when halogen atoms attach to the metal filament and most lost tungsten atoms redeposit on the filament when the bulb cools.
11th grade IB students invesigated the relative reactivity of the halogens by studying the reaction of halogens with sodium halides. Here colorless sodium iodide solution was reacted with chlorine water. Because chlorine is more reactive than iodine and the formation of the chloride ion in preference to the iodide ion shows this, purple iodine is seen in an oil level above the aqueous solution. 2NaI + Cl2 --> 2NaCl + I2.
The presence of iodine can be shown by adding starch solution. The solution goes blue.
Image to the left shows a rate of reaction lab--different concentrations of potassium iodate, KIO3, solution reacting with acidified sodium metabisulfite, Na2S2O5, liberating iodine which turns starch in the solution blue.
See VIDEO of this IB Chemistry iodine clock reaction
