Question

A decimolar solution potassium ferrocyanide is 50% dissociated at 300 K. The osmotic pressure of solution is (R = 8.314 J K$^{-1}$ mol$^{-1}$): 
 

• A. 7.48 atm
• B. 4.99 atm
• C. 3.74 atm
• D. 6.23 atm

Hint:

Osmotic pressure depends on van't Hoff factor, which accounts for the number of particles in solution.

Answer 1

The Correct Option is A

Step 1: Degree of Dissociation (\(\alpha\)) and Van't Hoff Factor (\(i\))
The reaction for dissociation of K$_4$[Fe(CN)$_6$] is: \[ K_4[Fe(CN)_6] \rightleftharpoons 4K^+ + [Fe(CN)_6]^{4-} \] Since the dissociation is 50\% (\(\alpha = 0.5\)), the total number of particles: \[ i = 1 + 4\alpha = 1 + 4(0.5) = 3 \] Step 2: Applying the Osmotic Pressure Formula
\[ \pi = iCRT \] Substituting values: \[ \pi = (3)(0.1)(8.314)(300) \] \[ \pi = 7.48 { atm} \] Thus, the correct answer is (A).