Physical Science:

Freezing point depression is a colligative property of a solution that describes how the presence of a solute lowers the freezing point of the solvent. Colligative properties are properties of solutions that depend on the concentration of solute particles in the solution, but not on the identity of the solute particles. The freezing point of a pure solvent is a characteristic property that is dependent only on the identity of the solvent. However, when a solute is added to the solvent, the freezing point of the resulting solution is lower than that of the pure solvent. This occurs because the solute particles disrupt the crystal lattice structure of the solvent, making it more difficult for the solvent molecules to form solid crystals.

Melting point elevation Melting point elevation is a colligative property of a solution that describes how the melting point of a solid solvent is increased when a solute is dissolved in it. Like freezing point depression, it is a property of solutions that depends on the concentration of solute particles in the solution, but not on the identity of the solute particles. When a solute is dissolved in a solvent, it disrupts the crystal lattice structure of the solvent, making it more difficult for the solvent molecules to transition from the solid to the liquid state. As a result, the melting point of the solution is higher than that of the pure solvent.