A supercritical fluid exists without a distinct liquid or gas phase and forms when temperatures and pressures exceed the substance’s critical point. Here supercritical transition is demonstrated with an ampule of liquid chlorine. When immersed in a hot bath, the temperature and pressure inside the ampule rises until around 0:20 when the meniscus marking the interface between liquid and gas disappears. The chlorine is now in its supercritical state. Around 0:43 the hot bath is removed and the chlorine begins to cool, reverting to distinct phases of matter around 0:55.
Tag: critical point
Shear-Thinning at Home
Shear-thinning isn’t just confined to canned whipped cream. It’s also a feature of such non-Newtonian fluids as ketchup, shampoo, latex paint, and blood. The NASA research on shear-thinning the video author refers to is here and comes from the Critical Viscosity of Xenon-2 (CVX-2) experiment flown on the final mission of Columbia. Surprisingly, almost all of the experimental data was recovered from the crash. #
Supercritical Fluids
Supercritical fluids live in the region of a phase diagram beyond the critical point. At these temperatures and pressures, a substance is neither strictly liquid nor a gas but exhibits behaviors from both. A supercritical fluid can effuse through a solid like a gas does but can also dissolve substrates like a liquid. As noted in the video above, supercritical fluids are useful substitutes for organic solvents in many industrial applications. Carbon dioxide, for example, is used as a supercritical fluid in the decaffeination process.
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