This video demonstrates some of the properties of carbon dioxide gas. Carbon dioxide gas is more dense than air. The gas can be poured kind of like a liquid. The video shows carbon dioxide gas being poured to extinguish a candle flame. A candle flame needs oxygen gas to burn. Since carbon dioxide gas is surrounding the flame, the lack of oxygen gas makes the flame go out. You could also use dry ice as a source of cargon dioxide instead of vinegar and baking soda.
materials needed
large poster board folded
video