Question

Which of the following solutions will have the highest osmotic pressure?

• A. 0.1 M \( KCl \)
• B. 0.1 M \( CaCl_2 \)
• C. 0.1 M Glucose
• D. 0.1 M Urea

Hint:

For questions comparing colligative properties, always look for the solute that produces the maximum number of ions upon dissociation.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Osmotic pressure (\( \pi \)) is a colligative property, meaning it depends on the number of solute particles present in a solution, rather than the type of particles. The more particles in solution, the greater the osmotic pressure.
Step 2: Detailed Explanation:
To determine which solution will have the highest osmotic pressure, we need to evaluate the number of particles \( i \) produced by each solute in the solution. The number of particles depends on how the solute dissociates or remains intact in solution:
- (A) \( KCl \) dissociates into \( K^+ \) and \( Cl^- \), producing 2 particles. Thus, \( i = 2 \).
- (B) \( CaCl_2 \) dissociates into \( Ca^{2+} \) and 2 \( Cl^- \), producing 3 particles. Thus, \( i = 3 \).
- (C) Glucose is a non-electrolyte and does not dissociate, so it produces 1 particle. Thus, \( i = 1 \).
- (D) Urea is also a non-electrolyte and does not dissociate, so it produces 1 particle. Thus, \( i = 1 \).
Since \( CaCl_2 \) dissociates into the maximum number of ions (3 particles), it will create the highest effective concentration of particles in solution, resulting in the highest osmotic pressure.
Step 3: Final Answer:
The solution with the highest osmotic pressure is 0.1 M \( CaCl_2 \), as it dissociates into the most particles (3 ions).