Iodine Demonstration of Sublimation - Journal of Chemical Education

Dec 1, 1995 - Iodine sublimation can be easily and effectively demonstrated on an overhead projector. Iodine crystals in a small beaker placed within ...
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DORISKOLB Bradley University Peoria, lL61625

Iodine Demonstration of Sublimation Robert H. Goldsmith St. Mary's College of Maryland St. Mary's City, MD 20686 The process of sublimation, in which a solid is directly converted into the gaseous state, is a n interesting and impressive phenomenon. It can be demonstrated readily using a n overhead projector. The element iodine provides a simple way to demonstrate sublimation in the classroom. Procedure A small amount of solid iodine is placed in a 10-mL beaker. This beaker is then placed inside a 250- to 400-mL

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Journal of Chemical Education

beaker that has been filled with ethanol or isopropanol up to a level of 1.5 to 2 cm from the bottom of the beaker. A watchglass or glass plate can be placed on the top of the beaker as a cover. This setup can now be placed on the stage of a n overhead projector and the image can be projected onto a nearby screen. Within a few minutes a light pink color may be observed on the screen. This demonstration may now be allowed to proceed a s the class continues. Within 15 to 20 min the alcohol begins to take on a definite yellowish tint. The color intensities as time progresses and becomes a yellowish-tan color. This demonstration clearly shows the dissolution of the iodine vapor, which could come only from the solid iodine. I t is a quick, easy to perform, and effective demonstration of the process of sublimation.