0.05 M CuSO4 when treated with 0.01 M K2Cr2O7 gives green colour solution of Cu2Cr2O7. The two solutions are separated as shown below : [SPM : Semi Permeable Membrane] [figure] Due to osmosis :
- Molarity of K2Cr2O7 solution is lowered.
- Green colour formation observed on side Y.
- Molarity of CuSO4 solution is lowered.
- Green colour formation observed on side X.
Answer
(3) Molarity of CuSO4 solution is lowered.
Solution
Osmotic pressure = iCRT, and the solvent flows through the SPM from lower π to higher π.
K2Cr2O7 2K+ + Cr2O72-: iC = 3 0.01 = 0.03 M
CuSO4 Cu2+ + SO42-: iC = 2 0.05 = 0.10 M
So water moves from side X to side Y and the CuSO4 solution is diluted: (3) is correct and (1) is wrong.
Since ions cannot pass through the SPM, Cu2+ and Cr2O72- never meet, so no green colour forms on either side: (2) and (4) are wrong.
Answer: (3)