For this demonstration I use my own special formula for extra strong soap bubbles. I use one part Dawn soap, one part glycerin, and two parts water. I dip the bottom end of the funnel into the soap bubble mixture and blow through the wide top to create large bubbles. The rest of the demo just needs an empty fish tank and some dry ice. This is one of my favorite demos to teach the concepts of the density and buoyancy of different gasses.
Can saltwater, water, alcohol, and shampoo be stacked? This is a very simple student inquiry activty (and one of my students' favorites) that can be done in class (download handout).
What happens to hot and cold water when placed in room temperature water? What if the water is colored? Watch the video for a simple demonstration of the properties of hot and cold water.
The Styrofoam cup. It seems like a simple unitasker, one that holds liquids and is a good insulator. Why is it a good insulator and so light? Styrofoam is the the brand name that Dow Chemical uses for its version of polystyrene. Polystyrene is a polymer, which is a substance that is made up of repeated units, monomers, bonded together. What makes Styrofoam special is the process in which it is made. During the process, gas is blown into the polystyrene causing the material to be mostly empty space. The Styrofoam is very low in density becuase the mass of the polystyrene is contained in a larger area. It is a good insulator because the air spaces that make up the foam deters heat energy flow. The above video demo shows what happens when the polystyrene is dissolved in acetone. The polystyrene structure basically collapses and condenses, leaving a hardened, more dense mass.