This video shows an experiment popular with high school students, but on a far bigger scale. Using a large bottle with a narrow opening and a small amount of isopropyl alchohol, Matthew Clough from Orangevale, California has produced a sound that will remind you of a whistle. It’s actually the sound of gas rapidly expanding inside the jug, trying to escape. The effect is caused by the energy of the match reacting with the flammable isopropyl. Credit: Matthew Clough