Question

Which of the following solutions will show highest freezing point depression?

• A. 1 M glucose
• B. 1 M NaCl
• C. 1 M AlCl3
• D. 1 M MgCl2

Hint:

The more particles a solute produces in solution, the higher the freezing point depression.

Answer 1

The Correct Option is C

Freezing point depression depends on the number of particles in solution. The van't Hoff factor \(i\) tells us how many particles a solute dissociates into. For 1 M solutions.
- Glucose does not dissociate, so \(i = 1\).
- NaCl dissociates into 2 ions, so \(i = 2\).
- AlCl3 dissociates into 4 ions, so \(i = 4\).
- MgCl2 dissociates into 3 ions, so \(i = 3\).
Thus, AlCl3 will cause the greatest freezing point depression, as it produces the most ions.