FeCl3 on reaction with K4[Fe(CN)6] in aq solution gives blue colour and these are separated by a semi permeable membrane Due to osmosis there is

Due to Osmosis neither FeCl3 nor K4[Fe(CN)6] move through semipermeable membraneBecause FeCl3& K4[Fe(CN)6] are the solutes in a solutionDue to osmosis only water flows from low concentration region to high concentration region.So no reaction occurs, so blue colouration is not observed