FeCl3 on reaction with k4 [Fe(CN) 6] in aqueous solution gives blue color. These are separated by a semi-permeable membrane. ... No blue color formation will occur to any of the sides because semipermeable membrane allow only solvent particle to pass through it but not allow solute particle to pass through it..

Osmosis and the Separation of Fe(cl)3 and K4(Fe(CN)6) by Semipermeable Membrane

Osmosis is the movement of solvent molecules from a region of low solute concentration to a region of high solute concentration through a semipermeable membrane. In this case, the solvent is water and the solutes are Fe(cl)3 and K4(Fe(CN)6). When these two solutions are separated by a semipermeable membrane PQ, osmosis occurs due to the concentration gradient of the solutes across the membrane.

Formation of Blue Colour

When Fe(cl)3 reacts with K4(Fe(CN)6) in an aqueous solution, a blue complex is formed known as Prussian blue. This is a coordination compound in which Fe(III) ion is surrounded by six CN- ions in an octahedral arrangement. The blue colour is due to the absorption of light by the complex in the visible range.

Osmosis and the Separation of Solutions

When Fe(cl)3 and K4(Fe(CN)6) are separated by a semipermeable membrane PQ, the solutes try to move across the membrane to equalize the concentration on both sides. However, the membrane only allows the movement of water molecules, not solute molecules. Therefore, water molecules move from the side of low solute concentration (i.e., the side with K4(Fe(CN)6)) to the side of high solute concentration (i.e., the side with Fe(cl)3) to dilute the solutes and equalize their concentrations. As a result, the volume of the Fe(cl)3 solution increases, and the volume of the K4(Fe(CN)6) solution decreases.

Conclusion

In summary, the osmosis of water molecules across a semipermeable membrane from a region of low solute concentration to a region of high solute concentration causes the separation of Fe(cl)3 and K4(Fe(CN)6) solutions. This is due to the concentration gradient of the solutes across the membrane. The blue colour observed is due to the formation of the Prussian blue complex.