Badding Research Group

Demonstrations and Fun

Supercritical Water Video

This first movie was kindly provided by Dr. Andy Shen and Prof. Bill Bassett of the Cornell University Department of Geological Sciences. It shows water going through its supercritical phase transition in a hydrothermal diamond anvil cell (see Bassett, W.A., Shen, A.H., Bucknum, M., and Chou, I-Ming (1993) A new diamond anvil cell for hydrothermal studies to 2.5 GPa and from -190 to 1200^oC. Rev. Sci. Instrum., 64, 2340-2345). What you see initially is a bubble of air together with some water contained in the diamond anvil cell sample chamber. You are looking through one of the diamonds of the cell. The amount of water and free space in the form of air (the small quantity of low density air has a negligible effect on the water) has been carefully chosen so that the system will go supercritical along upon heating along the isochore (i.e. constant volume trajectory). At first boiling within the bubble is shown, but at 1 minute, 44 seconds (you may want to download the file and open it with the quicktime player to see the time) the phase boundary between water vapor and liquid water simply disappears while the system is undergoing a supercritical phase transition. Phase separation into liquid + gaseous water is then shown at 2 minutes, 1 second, followed by criticality again. A brucite mineral crystal is in the upper right corner. Hydrothermal processes involving supercritical water are important to the formation of crystals of minerals within the earth and also are used for the fabrication of single crystals of materials such as quartz, used in every quartz watch.

 

Note: If the movie does not open in your browser, right click and save it to the desktop. Then open with the quicktime player.

Note that you must have Quicktime version 7 or later for mac or PC to play this video. A 1.5 GHz or faster machine is best.

Supercritical Carbon Dioxide Video

This second movie is of supercritical carbon dioxide. Initially the CO₂ is phase separated into liquid and gas. Then the heat gun is turned on, the liquid boils and expands, and then phase boundary (meniscus) between liquid and gas disappears. Next there is a second clip showing phase separation upon cooling the supercritical fluid. Critical opalescence is observed. It is easy to understand from this video why there is no surface tension in a "hybrid liquid/gas" supercritical fluid.

 

 

Note: same comments as above apply re quicktime.

 

 

Here is a different video clip of opalescence in supercritical CO₂. Here is another cool clip of supercritical SF₆.