The osmotic pressure of the equimolar solutions of the following at the same temperature will increase in order
(A) $NACl$
(B) $K_2SO_4$
(C) $K_3[Fe(CN)_6]$
(D) $NH_2CONH_2$
Choose the correct answer from the options given below.
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (D), (A), (B), (C)
Since all solutions are equimolar (same molar concentration C), the osmotic pressure depends only on the van’t Hoff factor (i):
|
Compound |
Formula |
Dissociation / Behaviour |
van’t Hoff factor (i) |
Osmotic pressure order |
|
(D) Urea |
NH₂CONH₂ |
Non-electrolyte (does not dissociate) |
i = 1 |
Lowest |
|
(A) NaCl |
NaCl |
→ Na⁺ + Cl⁻ |
i = 2 |
↓ |
|
(B) K₂SO₄ |
K₂SO₄ |
→ 2K⁺ + SO₄²⁻ |
i = 3 |
↓ |
|
(C) K₃[Fe(CN)₆] |
K₃[Fe(CN)₆] |
→ 3K⁺ + [Fe(CN)₆]³⁻ |
i = 4 |
Highest |
Increasing order of osmotic pressure:
(D) < (A) < (B) < (C)