This amplifies the higher frequencies in your voice. The gas sulfur hexafluoride works in the opposite way. The following is a transcript of the video. It’s a classic party trick- suck down a ...

Two chemicals that are expected to be banned are hydrofluorocarbons and sulfur hexafluoride, in favor of Co2, propane, and ammonia. The DEC said these latter chemicals are better for the environment.

Searching online will allow you to find clips of model boats made from aluminium foil floating in a tank full of sulfur hexafluoride. This clip will be relevant for teaching KS3 and GCSE Physics.