Build a Colorful Iodine Thermometer

[Rhodium]

Colorful Iodine Thermometer
Richard W. Ramette, J. Chem. Educ. 80, 878 (2003)

While teaching at Carleton College I liked telling my students that iodine is my favorite element, largely because of its colorful chemistry. On retirement, I made an iodine thermometer, comprising a few grams of the solid sealed in a 12-liter round-bottom flask. It sits in my back yard, giving a visual indication of the temperature with increasing sublimation pressure. In the morning, it is nearly colorless, but the Arizona sun works wonders as the day progresses. At night, condensation results in countless little violet-black crystals on the inner surface.

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Figure 1.
An iodine thermometer showing small iodine crystals that were deposited on
the inner surface of the flask by repeated solar vapor-solid transitions.

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Figure 2.
An iodine thermometer at midday provides a visual indication of the temperature
with increasing sublimation pressure—the deeper the color, the higher the temperature.

In case anyone wants to make an iodine thermometer, here's the procedure I followed. Use about a half-teaspoon of solid iodine. The trick is to keep water from getting in. Seal a glass plate to the neck of the flask, using silicone goop. When it is dry, set the inverted flask into a plastic jar lid and pour in plaster of paris. When that is dry, further seal it with more silicone. Just sealing with epoxy or silicone doesn't hold up because the iodine attacks it.

[Chewbacca]

That guys an idiot, what a waste of a 12lt RB flask  

[acid_egg]

Isn't that pretty! ...it's like a chemistry version of those plasma balls (you can make one of those from a GLS bulb btw)

[halfkast]

showing you have a general interest in chemistry could bee helpful.

acid_egg, a write-up on making one or even info would bee cool, on the couch or general. I always wanted a plasma ball  

[pHarmacist]

I always wanted a plasma ball

Visit your local 1-dollar-store...

[Tdurden969]

http://www.angelfire.com/80s/sixmhz/globe.html

Requires:

1. One flyback transformer
2. One Round bottom flask
3. A vac pump + argon
3. some other shiznit

[halfkast]

Tdurden969 thanks, Ill look in to it mate!