When a solute is dissolved in a solvent, it disrupts the ordering process of the solvent's particles, resulting in a lower freezing point for the solution. The freezing point depression, which is negative, is directly proportional to the molal concentration of the solute.
When a pure solvent freezes, its particles become more ordered as the intermolecular forces that operate between the molecules become permanent. By dissolving a solute into the solvent, this ordering process is disrupted, requiring more energy to be removed from the solution in order to freeze it. This results in a lower freezing point for the solution compared to the pure solvent.
The decrease in freezing point, or freezing point depression (ΔTf), is directly proportional to the molal concentration of the solute. The formula for calculating the freezing point depression is: ΔTf = Kf × m, where Kf is the molal freezing point depression constant and m is the molality of the solution.
It is important to note that the freezing point depression is negative because the freezing temperature of the solution is lower than that of the pure solvent.
Complete Question:
Derive a formula, similar to equation 5.90 which was T-Tnot = (nB*k*Tnot^2)/L for the shift in the freezing temperature of a dilute soution. Assume that the solid phase is pure solvent, no solute. You should find that the shift is negative: The freezing temperature of a solution is less than that of the pure solvent. Explain in general terms why the shift should be negative.