<Dd> Π = n R T i V = c R T i (\ displaystyle \ Pi = (\ frac (nRTi) (V)) = cRTi) </Dd> <P> The osmotic pressure is proportional to the concentration of solute particles ci and is therefore a colligative property . </P> <P> As with the other colligative properties, this equation is a consequence of the equality of solvent chemical potentials of the two phases in equilibrium . In this case the phases are the pure solvent at pressure P and the solution at total pressure P + π . </P> <P> The word colligative (Latin: co, ligare) was introduced in 1891 by Wilhelm Ostwald . Ostwald classified solute properties in three categories: </P>

Why is density and viscosity not considered colligative properties