FeCl3 on reaction with potassium ferrocyanide in aqueous solution gives blue colour When 0 01M of FeCl3 and 0 1M - Chemistry - Solutions

Question

FeCl3 on reaction with potassium ferrocyanide in
aqueous solution gives blue colour When 0 01M of FeCl3
and 0 1M potassium ferrocyanide are placed in a beaker and
seperated by a semi permeable membrane, identify whether there will
be an appearance of blue colour on potassium ferrocyanide side due
to osmosis E xplain your answer

Kanika Dalal · Accepted Answer

The equation for the reaction of FeCl3 and K4
[Fe(CN)6] is

4 FeCl3 + 3 K4 [Fe(CN)6]

â†’ 
Fe4[Fe(CN)6] + 12 KCl
Ferri-ferro cyanide
Therefore the blue colour of the solution is due to the formation
of ferri-ferro cyanide complex When 0 01M of
FeCl3and
0 1M potassium ferrocyanide are placed in a beaker and seperated by
a semi permeable membrane the movement of only water molecules will
take place across the membrane from FeCl3 side to
potassium ferrocyanide side due to osmosis (Osmosis is the
diffusion of solvent molecules through a semi permeable membrane
into a region of high solute concentration) The movement of water
molecules will stop when there equal concentration of solutions on
both sides of the membrane This means that no
FeCl3molecules
would move across the membrane to potassium ferrocyanide side Hence
there will be no formation of ferri-ferro cyanide complex because
of which blue colour will not appear in potassium ferrocyanide
side