Sulfur Hexafluoride Demonstrations

Fun with Sulfur Hexafluoride, the Anti-Helium

Sulfur hexafluoride is non-toxic, colorless, non-flammable and six times heavier than air. You can float a light boat on the invisible gas.
Sulfur hexafluoride is non-toxic, colorless, non-flammable and six times heavier than air. You can float a light boat on the invisible gas. Mark Airs / Getty Images

Sulfur hexafluoride is a non-toxic, invisible gas that you can use to perform interesting chemistry demonstrations. Breathe it in and make your voice much deeper when you talk. Pour it into a container and float an airplane or a ship on 'nothing'. In a way, it is like the anti-helium gas, because while helium is about six times lighter than air, sulfur hexafluoride is six times heavier.

Sulfur Hexafluoride Facts

  • Inorganic compound with a chemical formula SF6
  • Non-polar gas
  • Non-toxic, odorless, colorless
  • nNn-flammable at room temperature and pressure
  • Octahedral geometry
  • Poorly soluble in water; soluble in nonpolar organic solvents
  • Density of 6.13 g/L at sea level

Fun Things to Try with Sulfur Hexafluoride

  • Float Your Boat
    Pour sulfur hexafluoride into an aquarium or large beaker. It is heavier than air, so it will sink. You can float light objects on the invisible gas, such as a paper airplane or a boat made from aluminum foil. If you use a cup to scoop up some of the sulfur hexafluoride and dump it into a foil boat, you can sink it.
  • Talk or Sing with a Deep Voice
    Sulfur hexafluoride is more dense than air, so sound travels through it more slowly. If you breathe in a lungful of sulfur hexafluoride, your voice will become much deeper. Even though sulfur hexafluoride is non-toxic, you need to use care when performing this demonstration to avoid hypoxia and fainting (the same caution applies to helium). Don't breathe the gas for prolonged periods of time.

    Where Can You Get Sulfur Hexafluoride?

    Sulfur hexafluoride is a specialty gas, used in medicine for eye surgery and ultrasound imaging; in industry as a tracer gas, dielectric, and as an etchant; and mixed with argon as an insulator between layers of windows. It has enough uses that you may be able to find it at a store that sells specialty gasses (try the yellow pages), such as oxygen, argon, and nitrogen.