osmotic potential

Osmotic potentialclick for a larger image
Fig. 239 Osmotic potential . Osmosis through a differentially permeable membrane.

osmotic potential (OP value)

a measure of the tendency of a solution to withdraw water from pure water by OSMOSIS across a differentially permeable membrane. Pure water has an osmotic potential of zero at one atmosphere pressure. The OP value of any solution is always negative. Osmotic pressure is a measure of the tendency for water to move into a solution by osmosis, and is expressed as a positive value.