Question

A centi molar solution of acetic acid is 50% dissociated at 27$^\circ$C. The osmotic pressure of the solution (in atm) is (R = 0.083 L atm K$^{-1}$ mol$^{-1}$)

• A. 0.37
• B. 3.7
• C. 0.037
• D. 0.73

Hint:

Use $\pi = iCRT$ for osmotic pressure, where $i$ accounts for ionization or association.

Answer 1

The Correct Option is A

C = 0.01 mol/L (centi molar)
Dissociation = 50% $\Rightarrow$ van't Hoff factor $i = 1 + \alpha = 1 + 0.5 = 1.5$
$\pi = iCRT = 1.5 \times 0.01 \times 0.083 \times 300 \approx 0.3735 \approx 0.37$ atm