Dry ice

Dry Ice is frozen carbon dioxide, a normal part of our earth's atmosphere. It is the gas that we exhale during breathing and the gas that plants use in photosynthesis. It is also the same gas commonly added to water to make soda water. Dry Ice is particularly useful for freezing, and keeping things frozen because of its very cold temperature -78.5oC. Dry Ice changes directly from a solid to a gas (sublimation) in normal atmospheric conditions without going through a wet liquid stage.

Fire & dry ice: Carbon dioxide is not flamable. When sublimating the CO2 gases surround the flame and cutting off oxygen supply, which is necessary to sustain the fire. In the result the flame is extinguished.

Floating soap bubble: The air exhaled into the bubble is less dense than the gases comprising the dry ice, but slightly heavier than the air surrounding the bubble. So although the bubble doesn't float in the air, it does float on the heavier dry ice smoke.

Dry ice explosion: A dry ice bomb simply consists of dry ice that is sealed in a rigid container. The dry ice sublimates to form carbon dioxide, which exerts pressure on the wall of the container until it explode.