Osmotic pressure- The excess pressure is exerted on the surface of solution to just prevent Osmosis is called osmotic pressure. It depends upon the molal concentration. Hence it is a colligative property.
According to van't Hoff π ∝ C (At constant temp.) and π ∝ t (At constant concentration) Both laws are combined, we have
π ∝ cT and c = n/V
π = RcT
∴ π = (n/V)RT
or, πV = nRT
or, π = (W/M)RT
where, M = Molecular weight and
R = Gas constant
