Believe it or not, research scientists have actually concluded that Diet Coke produces the best stream of flying soda (much to the joy of the Mentos Experiment enthusiasts). I received an email from Dr. Joe Maglaty, Director of Education Outreach from the Merck Institute for Science Education with this information:
I recently came across an article that you may, or may not, be aware of. In the April issue of the Journal of Chemical Education, a chemistry professor from Illinois State Univ. took on the analytical process for showing gas solubility in aqueous solution – that is, how much carbon dioxide (CO2) is released from soda (pop) using ultrasonic energy. Since ultrasonic waves provide millions of nucleation sites at the wave nodes inside the soda bottle, this technique is much more effective in releasing CO2 than any physical substance, such as Mentos or Lifesavers. The quantitative results are quite impressive, with the bottom line being that Diet Coke at room temperature is the best way to eject most of the soda into a fountain.
The Journal of Chemical Education article probably gives you more information that you’d ever want on the topic. A PDF of the full text is also at this location. With this phenomena of releasing carbon dioxide quickly from a gas/liquid mixture, more teachers should take advantage of this opportunity to explore this science with their students. Everyone should share in this excitement and be involved with inquiry based, hands-on and minds-on science activities that helps us understand and learn from the world around us.