tripelpunkte

Tripelpunkte describe the specific temperature and pressure at which three distinct phases of a substance, typically solid, liquid, and gas, can coexist in thermodynamic equilibrium. At this unique point, no matter how much time passes, the amount of each phase remains constant. This equilibrium is achieved when the chemical potential of each phase is identical. The tripelpunkt is a characteristic property of each pure substance and serves as a fixed point for temperature calibration. For example, the tripelpunkt of water is precisely 273.16 Kelvin (0.01 degrees Celsius) and 611.657 pascals. This precise and reproducible nature makes the tripelpunkt valuable in scientific measurements. The existence of a tripelpunkt implies that below its pressure, a liquid phase cannot exist; the substance will transition directly from solid to gas (sublimation). Conversely, above its pressure, the solid phase may not be stable at certain temperatures. Understanding tripelpunkte is fundamental in thermodynamics and phase diagrams, aiding in the prediction of a substance's behavior under various conditions.