Guldberg’s rule

Graphical representation, 423 Gravity, 21, 201 Griineisen s relation, 486 Guldberg s rule, 234... 

Ramsay and Young also found that for a given pressure the ratio of the absolute temperature to the absolute critical temperature is approximately consent. This is an extension of Guldberg s rule ( 7.VII C). Adams found that the b.p. abs. at p atm. is related to that at 1 atm. by the formula ... 

Since Tb is approximately fTc (Guldberg s rule, 7.VH B), LJTe should be approximately constant. J. J, Thomson deduced from some general considerations that this should be so, and showed that it was approximately verified by the experimental results. 

Supercritical fluids make ideal solvents because their density is only about 30% that of a normal fluid, a factor sufficient to provide for good solvent capability, but low enough for high diffusivity and rapid mass transfer. A sample of gas is supercritical whenever its temperature and pressure are above thar critical values, but in practice the operating temperatures are not far above 7. A simple way to predict the solvent characteristics of a low-boiling substance in its supercritical state is to compare the boiling point (Ti,) and critical temperature (TJ of substance. The Guldberg s rule ... 

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