Chemistry

Demonstrating the magnetic ink used in printing US currency has proven to engage audiences of all ages because of its relevance to everyday life. Nearly everyone has used machines that distribute and/or accept currency but few understand how the machines distinguish between the various denominations. The key is in the face of each denomination.

Penney Sconzo presented this nifty demonstration at the ChemEd 2015 Generations Symposium in Kennesaw State University, Kennesaw GA. This is an easy, colorful and safe microscale version of the Ammonia Fountain.

For years I believed that solid iodine, I2, only underwent sublimation when heated at atmospheric pressure. I was so wedded to this idea that I performed the demonstration for years.

Citric acid is a user-friendly, inexpensive, water-soluble, crystalline solid carboxylic acid. In comparison to using hydro-chloric acid solutions, using solid citric acid and its solutions in water is safer and more convenient. For inexperienced students its titrations against strong base are easier to perform.