Question

How does freezing point depression work? Why does the addition of a solute lower the freezing point?

Answer 1

It works when a non-volatile substance is added to a solvent. Usually the pure solvent is water in many questions. Non-volatile substances don't produce any vapor pressure. So when adding a non-volatile substance to water, part of the mixture does not create a vapor. Also, they do not form part of the solid when water freezes since usually the substance is a solid. It obstructs the crystal formation of the H20 and thus requires a lower freezing temperature...