How does a nonvolatile solute affect the freezing point of a solution?

When a nonvolatile solute is added to a solvent, it results in a phenomenon known as freezing point depression. This means that the freezing point of the solution is lowered compared to that of the pure solvent.

The presence of a nonvolatile solute disrupts the formation of the crystalline structure required for freezing by preventing the solvent molecules from coming together. As a result, a greater energy decrease must be achieved for the solution to freeze, effectively lowering the temperature at which this process occurs.

This effect can be quantitatively described by the formula for freezing point depression, which is directly related to the molality of the solute in the solution and the freezing point depression constant of the solvent. The more solute particles present, the greater the reduction in the freezing point. This is particularly relevant in real-world applications, such as how salt is used to lower the freezing point of water on roads in winter. Thus, adding nonvolatile solute consistently results in a decreased freezing point of the solvent.