We shall, in the first place, consider only the triple point S-L-V.
On passing through the triple point, therefore, there will be a change of the one form into the other.
As to the general arrangement of the three univariant curves around the triple point, the following rules may be given.
The prolongation of each of the curves beyond the triple point must lie between the other two curves.
The triple point S-S-V is not precisely the same as the transition point, but is very nearly so.
The limiting temperature for these two cases, at which the division into three phases may occur, is called the triple point.
It is possible, too, that long before the triple point is reached the whole liquid will have evaporated.
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.