When we add sugar or salt to water, the freezing point of water decreases. This is because the solute particles (sugar or salt molecules) interfere with the formation of ice crystals. In order for water to freeze, water molecules must be able to move freely and form into a crystalline structure. However, when solute particles are present, they get in the way of the water molecules and prevent them from forming crystals. This means that the water needs to be cooled to a lower temperature in order to freeze.

The amount that the freezing point decreases depends on the concentration of the solution. The more solute particles there are, the lower the freezing point will be.

This phenomenon is important in a number of applications, such as:

* Preserving food. Sugar and salt are often used to preserve food because they prevent it from freezing and spoiling.

* De-icing roads. Salt is used to de-ice roads and sidewalks because it lowers the freezing point of water and makes it easier to melt ice.

* Preventing frost damage. Sugar and salt can be used to prevent frost damage to plants by spraying them on the plants before a frost.

It is important to note that the freezing point of water is not the only thing that is affected by the presence of solute particles. The boiling point of water also increases when solute particles are present.