Kookpunt

Kookpunt is the Dutch term for boiling point. It denotes the temperature at which a liquid’s vapor pressure equals the surrounding pressure, causing the liquid to boil and form vapor. The concept applies to pure substances and to mixtures, but the exact boiling behavior depends on composition and pressure.

At standard atmospheric pressure (1 atmosphere, 101.3 kPa), the normal boiling point is the temperature at which the liquid boils under those conditions. Water boils at 100°C; ethanol at about 78.37°C; acetone around 56°C. Many substances have much higher or lower boiling points; for example, nitrogen boils at −196°C and mercury boils at 357°C.

Boiling point changes with external pressure. Increasing pressure raises the boiling point; decreasing pressure lowers it. At higher elevations, liquids tend to boil at lower temperatures, which can affect cooking, heating, and industrial processes.

In solutions and mixtures, boiling behavior can differ from that of the pure solvent. Dissolved solutes often raise the boiling point (boiling point elevation). Some mixtures form azeotropes, where the composition and boiling temperature remain fixed during distillation, limiting separation by simple boiling.

Measurement and applications. Boiling point can be determined using methods such as capillary tube boiling point determination or differential scanning calorimetry. It is a fundamental property in chemistry and chemical engineering, used to select solvents, design distillation processes, and assess volatility and safety of liquids.