March 27 2012 3 27 /03 /March /2012 02:17
I made some iodine by reacting tincture of iodine with some hydrochloric acid and adding some sodium hypochlorite. A solution of iodine monochloride was made because of excess hydrochloric acid. I then added sodium bicarbonate until flecks of iodine precipitated. The iodine then coagulated, making it easy to filter. It was filtered and began drying, although the evaporation was significant. The paper was stained brown all around the iodine crystals, showing that the iodine vapor reacted with the moist starch. I scraped off a bit of iodine when it was almost dry and placed it in a container.
The iodine in the container was then placed in a hot tap water bath. The coloration of iodine vapor was faintly visible. When the vial is placed in boiling water, however, the coloration is much more intense. When the vial cools, microscopic crystals of pure iodine are deposited on the walls of the vial.
Here is a video of the sublimation: