What is a Supercritical Gas?
Supercritical gas, more correctly known as supercritical fluid, is a distinct state of matter that has properties of both a liquid and a gas. A supercritical gas may be regarded as an intermediary state between liquids and gases. Supercritical gases are only created above a material’s thermodynamic critical point. This usually means high pressures, often between about 40 and 80 atmospheres, though it varies greatly. Some critical points, most notably water, are as high as 218 atmospheres and beyond. Supercritical fluids have low viscosities and high diffusivities. Supercritical gases can diffuse into and through solids like a gas, but also dissolves certain materials like a liquid. Supercritical fluids are found in at least two areas of nature. The first is around hydrothermal vents and submarine volcanoes on the ocean floor, where the pressure is so great that the creation of a supercritical gas is possible. The pressure 3 km (1.8 mi) underwater is 300 atmospheres, more than enough. A
