List the following aqueous solutions in order of decreasing freez...

Question

List the following aqueous solutions in order of decreasing freezing point: 0.040 m glycerin (C3H8O3), 0.020 m KBr, 0.030 m phenol (C6H5OH).

Accepted Answer

Step 1: Understand that the freezing point of a solution is affected by the number of solute particles in the solution, which is described by the colligative property known as freezing point depression.. Step 2: Recall the formula for freezing point depression: $ \Delta T_f = i \cdot K_f \cdot m $, where $ \Delta T_f $ is the change in freezing point, $ i $ is the van't Hoff factor, $ K_f $ is the freezing point depression constant, and $ m $ is the molality of the solution.. Step 3: Determine the van't Hoff factor $ i $ for each solute: Glycerin (C3H8O3) is a non-electrolyte, so $ i = 1 $; KBr is an electrolyte that dissociates into K+ and Br-, so $ i = 2 $; Phenol (C6H5OH) is a weak electrolyte, but for simplicity, assume $ i = 1 $.. Step 4: Calculate the effective molality for each solution by multiplying the molality by the van't Hoff factor: Glycerin: $ 0.040 \times 1 = 0.040 $, KBr: $ 0.020 \times 2 = 0.040 $, Phenol: $ 0.030 \times 1 = 0.030 $.. Step 5: Rank the solutions in order of decreasing freezing point. The solution with the lowest effective molality will have the highest freezing point. Therefore, the order is: Phenol (0.030 m), Glycerin (0.040 m), KBr (0.040 m).