Van't Hoff 1901 Nobel Lecture
|Van't Hoff JH (1901) Osmotic pressure and chemical equilibrium. Nobel Lecture December 13, 1901.|
Abstract: What is osmotic pressure? When a solution, e.g. of sugar in water, is separated from the pure solvent − in this case water − by a membrane which allows water but not sugar to pass through it, then water forces its way through the membrane into the solution. This process naturally results in greater pressure on that side of the membrane to which the water is penetrating, i.e. to the solution side.
It is thanks to this osmotic pressure that the sap of the oak-tree rises to the topmost twigs. This pressure was known to exist as long ago as the beginning of the 19th century, but it is only somewhat more than 20 years ago since this phenomenon has been the subject of precise measurements. It was the botanist Pfeffer who first measured this pressure in 1877 by making a membrane which satisfied the following three conditions: It was permeable to water, impermeable to sugar, and it withstood the by no means negligible pressure to which it was subjected.
Osmotic forces are in fact unexpectedly great: with a 1% sugar solution they are equal to no less than 2/3 atm.
• Bioblast editor: Gnaiger E
Force or pressure? - The linear flux-pressure law
- "For many decades the pressure-force confusion has blinded the most brilliant minds, reinforcing the expectation that Ohm’s linear flux-force law should apply to the hydrogen ion circuit and protonmotive force. .. Physicochemical principles explain the highly non-linear flux-force relation in the dependence of LEAK respiration on the pmF. The explanation is based on an extension of Fick’s law of diffusion and Einstein’s diffusion equation, representing protonmotive pressure ― isomorphic with mechanical pressure, hydrodynamic pressure, gas pressure, and osmotic pressure ― which collectively follow the generalized linear flux-pressure law."
- Gnaiger E (2020) Mitochondrial pathways and respiratory control. An introduction to OXPHOS analysis. 5th ed. Bioenerg Commun 2020.2. https://doi.org/10.26124/bec:2020-0002
- » pressure = force × free activity
Made history, Pressure, BEC 2020.2