triple point n.
The temperature and pressure at which three different phases, such as gaseous, liquid, and solid phases, of a particular substance can coexist in equilibrium.
triple point The temperature and pressure at which a substance can exist in equilibrium in the liquid, solid, and gaseous states. The triple point of pure water is at 0.01°C (273.16K, 32.01°F) and 4.58 mm (611.2Pa) of mercury and is used to calibrate thermometers. Compare critical point. |
In physics, the temperature at which all three phases of matter (solid, liquid, and gas) for a given substance can coexist.
Note: The triple point for water is a little above the freezing point, and is used to define temperature scales.