the quantity (concentration) of dissolved substances in a solution.

A measure of solute concentration in aqueous solution. A 1 M solution of a single non-dissociating solute has an osmolarity of 1 osmol. A physiologic osmolarity is about 300 mOs, roughly equivalent to 150 mM NaCl (NaCl dissociates into Na+ and Cl-, both of which contibute to osmolarity).

Measure of number of dissolved particles in solution. Inversely related to concentration of water.

particles of a solute per liter of solvent.

measure of ion concentration in a solution

The concentration of osmotically active particles in solutions expressed in terms of osmoles of solute per liter of solution.