Which aqueous solution would you expect to have the lowest freezing point? (a) 0.10 molal glucose,C6H12O6, or (b)0.10 molal NaCl solution
delta T = i*Kf*m
i = number of particles in the solution.
Kf = freezing point constant.
m = molality.
To determine which aqueous solution would have the lowest freezing point, we need to consider the concept of freezing point depression. Freezing point depression occurs because the presence of solute particles in a solution reduces the ability of the solvent to form a solid.
The degree of freezing point depression is directly proportional to the concentration of solute particles in the solution. In other words, the more solute particles present, the lower the freezing point of the solution.
Now, let's compare the two given solutions:
(a) 0.10 molal glucose, C6H12O6:
A 0.10 molal glucose solution would contain 0.10 mol of glucose dissolved in 1 kg of water. Glucose does not ionize in water; it remains as individual molecules. Therefore, in this solution, we have 0.10 mol of solute particles (glucose molecules).
(b) 0.10 molal NaCl solution:
A 0.10 molal NaCl solution would contain 0.10 mol of NaCl dissolved in 1 kg of water. NaCl readily dissociates in water to form Na+ and Cl- ions. In this solution, we have 0.10 mol of Na+ ions and 0.10 mol of Cl- ions, amounting to a total of 0.20 mol of solute particles.
Since the NaCl solution has a greater concentration of solute particles (0.20 mol) compared to the glucose solution (0.10 mol), it will exhibit a greater freezing point depression. Therefore, the NaCl solution will have the lowest freezing point between the two given solutions.
It is important to note that this explanation is based on the concept of ideal solutions, where the solute and solvent exhibit ideal behavior with respect to their interactions.
To determine which aqueous solution would have the lowest freezing point, we need to consider the concept of freezing point depression, which states that the presence of a solute in a solvent lowers the freezing point of the solution compared to the pure solvent.
The extent of freezing point depression depends on the number of solute particles present in the solution, rather than the type of solute. This means that the one with a higher concentration of solute particles will have a greater freezing point depression.
Let's compare the number of solute particles in each solution:
(a) 0.10 molal glucose (C6H12O6):
Glucose is a nonelectrolyte, meaning it does not dissociate into ions when dissolved in water. In this case, 0.10 molal glucose means 0.10 moles of glucose per kilogram of water.
(b) 0.10 molal NaCl solution:
NaCl is an electrolyte, and when it dissolves in water, it forms Na+ and Cl- ions. Thus, 0.10 molal NaCl solution contains 0.10 moles of NaCl per kilogram of water, resulting in double the number of particles than the glucose solution.
Because the NaCl solution has twice as many solute particles as the glucose solution, it will cause a greater freezing point depression. Therefore, the 0.10 molal NaCl solution would be expected to have the lowest freezing point.