Question

Calculate van't Hoff factor for \(\text{CaCl}_{2}\), if osmotic pressure of \(\text{CaCl}_{2}\) and urea solutions of same concentrations at same temperature are \(0.65\) and \(0.27\) atm respectively.

• A. \(1.95\)
• B. \(2.1\)
• C. \(2.9\)
• D. \(2.41\)

Hint:

Urea does not dissociate, so the van't Hoff factor is the ratio of the observed osmotic pressures.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept
Osmotic pressure is \(\pi=iCRT\). Urea does not dissociate, so for urea \(i=1\).

Step 2: Take the ratio
The concentration and temperature are the same, so \(\frac{\pi_{\text{CaCl}_2}}{\pi_{\text{urea}}}=\frac{i}{1}\).

Step 3: Calculation
\(i=\frac{0.65}{0.27}=2.41\), option (D).

Final Answer:
The van't Hoff factor of CaCl2 is about 2.41. \[ \boxed{\text{(D) }2.41} \]