Question

Question #8fe7a

Answer 1

Supercritical carbon dioxide is a fluid state of `CO_2` at which both the temperature and the pressure exceed the critical point - the highest temperature and pressure at which the substance can exist as a vapor and liquid in equilibrium - of `31^@C` ( or 304.15K) and `73atm`.

http://scienceline.ucsb.edu/getkey.php?key=4120

If you look at `CO_2`'s phase diagram, this region corresponds to the upper-right portion of the diagram. When in a supercritical state, `CO_2` has both gas-like and liquid-like qualities - it acts as a supercritical fluid for which distinct gas and liquid phases do not exist.

Supercritical fluids can dissolve materials like a liquid and effuse through solids as a gas, and are often used as a substitute for organic solvents for industrial or laboratory processes. This dissolving ability can be apllied to extract, purify, recristallize, infuse, or fractionate various materials

By controlling its temperature and/or pressure, supercritical `CO_2` can be made to dissolve a wide range of materials.

Here's a YouTube video on supercritical `CO_@`