jäätumispunkti

Jäätumispunkt refers to the temperature at which a liquid freezes or solidifies into a solid. For pure substances, the freezing point and melting point are the same. This transition occurs when the kinetic energy of the molecules is low enough for intermolecular forces to hold them in a fixed, ordered structure. The crystalline structure of the solid is formed at the freezing point.

The freezing point of a substance can be influenced by pressure. Generally, increasing pressure raises the freezing point of most substances, but water is an exception where increased pressure lowers its freezing point. Impurities also significantly affect the freezing point. Dissolving a solute into a solvent, such as salt in water, typically lowers the freezing point of the solvent. This phenomenon is known as freezing point depression and is a colligative property, meaning it depends on the concentration of solute particles rather than their specific identity.

Freezing point depression is utilized in various practical applications. For instance, adding antifreeze to a car's radiator lowers the freezing point of the coolant, preventing it from freezing and damaging the engine in cold weather. Similarly, spreading salt on icy roads lowers the freezing point of water, causing the ice to melt. Understanding and manipulating freezing points are crucial in fields like chemistry, physics, meteorology, and engineering.