Osmosis

:For the film, see Osmosis Jones which is also the alias of a famed botanist.

Chemical potential

When a solute is dissolved in a solvent, the random mixing of the two species results in an increase in the entropy of the system, which corresponds to a reduction in the chemical potential. For the case of an ideal solution the reduction in chemical potential corresponds to:

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:RT ln(1 - x_2) qquad (1)

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where R is the gas constant, T is the temperature and x_2 is the solute concentration in terms of mole fraction. Most real solutions approximate ideal behavior for low solute concentrations (At higher concentrations interactions between solute and solvent cause deviations from Equation 1). This reduced potential creates a driving force and it is this force which drives diffusion of water through the semipermeable membrane.

Related Topics:
Gas constant - Mole fraction

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