How to Make Iodine Crystals With Titratable Iodine

Grow iodine crystals on pieces of cork.

Growing crystals is not only entertaining, it shows students how crystals grow in nature. Since artificial crystals grow faster than natural ones, students can observe how they build on one another in a matter of days. Iodine produces lovely blue crystals, though they aren't stable and shouldn't be handled or they will melt. However, you can display a little garden of iodine crystals in a plastic container. Titratable iodine is more concentrated and drips more freely than common iodine; it should create crystals with a slightly more complicated structure and darker color.

Things You'll Need

• Plastic container
• Cork pieces
• Titratable iodine
• Salt

Instructions

1. Break up cork (wine stoppers, coasters, etc.) into quarter-sized pieces and scatter them in a single, tight layer in the bottom of your plastic container.

2. Mix about 1/2 cup of water with 2 tbsp. each of titratable iodine and non-iodized salt. Stir until everything is mixed together and pour it over your cork pieces. Drip more iodine on each cork piece and sprinkle salt on top of your drops.

3. Set the plastic container in a warm, sunny area. Crystals should begin to form within about 24 hours; they will be blue. Keep your garden growing by adding more water and iodine to the bottom of the container and sprinkling salt on top.

References

• Bizarre Labs: Charcoal Crystal Garden
• Newton: Iodine Crystal Formation
• Britannica: Titration
• Iodine: Iodine Disinfectant