arrange the following aqueous solutionsin order of increasing freezing points(lowest to highest temperature): 0/10m glucose, 0.10m BaCl2, 0.20mNaCl, and 0.20m Na2SO4.
To determine the order of increasing freezing points of these aqueous solutions, you need to consider their respective concentrations and the effect of the solute on the freezing point of the solvent.
The freezing point depression is a colligative property, which means it depends on the number of solute particles rather than their identity. In general, the greater the number of solute particles in a solution, the greater the freezing point depression.
To compare the number of solute particles in each solution, you can use a concept called "van't Hoff factor," which represents the number of particles formed after the solute dissociates in solution.
0.10 M BaCl2:
BaCl2 dissociates into three ions: Ba^2+ and 2 Cl^- ions. Therefore, the van't Hoff factor for BaCl2 is 3.
0.20 M NaCl:
NaCl dissociates into two ions: Na^+ and Cl^- ions. Hence, the van't Hoff factor for NaCl is 2.
0.20 M Na2SO4:
Na2SO4 dissociates into three ions: 2 Na^+ ions and one SO4^2- ion. Therefore, the van't Hoff factor for Na2SO4 is 3.
0.10 M glucose (C6H12O6):
Glucose does not dissociate into ions in solution, so its van't Hoff factor is 1.
Now, arrange the solutions in order of increasing freezing points based on their respective van't Hoff factors:
- Glucose (C6H12O6): van't Hoff factor = 1
- NaCl (0.20 M): van't Hoff factor = 2
- BaCl2 (0.10 M): van't Hoff factor = 3
- Na2SO4 (0.20 M): van't Hoff factor = 3
Therefore, the increasing order of freezing points (from the lowest to the highest temperature) would be: Glucose < NaCl < BaCl2 < Na2SO4.
To arrange the aqueous solutions in order of increasing freezing points, we need to consider the concept of colligative properties, specifically freezing point depression.
The freezing point depression is directly proportional to the molality (moles of solute per kilogram of solvent). The greater the molality, the greater the freezing point depression. Additionally, ionic solutes tend to have a greater effect on lowering the freezing point compared to molecular solutes.
Let's arrange the solutions in increasing order of freezing points:
1. The molecular solution of glucose, 0.10 m glucose:
- This is a molecular solute, and its effect on the freezing point depression is lower than the ionic solutes.
- Freezing point: relatively higher
2. The ionic solution of BaCl2, 0.10 m BaCl2:
- This is an ionic solute with a higher concentration than 0.10 m glucose.
- Ionic solutes tend to have a greater effect on freezing point depression.
- Freezing point: lower than 0.10 m glucose
3. The ionic solution of NaCl, 0.20 m NaCl:
- This is also an ionic solute but with a higher concentration than BaCl2.
- Higher concentration further lowers the freezing point.
- Freezing point: lower than 0.10 m BaCl2
4. The ionic solution of Na2SO4, 0.20 m Na2SO4:
- This is another ionic solute with a concentration similar to NaCl.
- The freezing point depression will be similar to NaCl.
- Freezing point: relatively lower than the previous solutions.
Therefore, the arrangement from lowest to highest freezing points is as follows:
0.10 m glucose < 0.10 m BaCl2 < 0.20 m NaCl < 0.20 m Na2SO4