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Unformatted text preview: urther, the gas and liquid densities to become become more similar. http://www.chem.leeds.a c.uk/People/CMR/critica lpics.html "supercritical fluid" shows properties of both liquids and gases --- behaves as a gas, takes on --the shape and size of the container. container --- has a density approaching density that of a liquid-incompressible! “liquid solvents” The The basic components of a supercritical CO2 cleaning system. Critical Critical Phenomenon Supercritical fluid (SCF): a "non-compressible” and high nonhigh density fluid". SCF SCF has high thermal high motion, and it is possible to change the density density widely (from low like like a gas to high like a liquid) intermolecular The greater the intermolecular force of a substance, the more readily a gas is liquefied, the higher the critical temperature Critical Critical T and P http://www.chem.purdue.edu/gchelp/liquids/critical.html Phase Phase diagrams: H2O vs. CO2 (a) P↑ mp↓ (unusual) H2O has normal MP, no normal sublimation point. (a) P↑ mp↑ (common) W (b) TP at high P (b) TP at low P CO2 has no normal MP, only normal sublimation point. 1. Which substance (s) cannot be liquefied at room temperature (298 K)? Ar, N , O 2 2 4 2. Compare each pair of similar compounds above, which one has higher critical temperature? How about critical pressure? The higher polarity → the higher critical temperature as well as the higher critical pressure!...
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This document was uploaded on 02/26/2014.

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