What is the Triple Point Temperature?
The triple point is the temperature at which the solid, liquid, and gas phases of a substance co-exist, and is also dependent on the pressure. Sometimes only the term triple point is used, which refers to both the temperature and the pressure at which the three phases co-exist in equilibrium. The triple point of water is 273.16 K at 611.73 Pa. This is the basis of the Kelvin scale and it is equal to 0.01 оC, which is the freezing point of water. A change in temperature or pressure causes one of the phases to fade away and therefore this measurement is constant. The triple point temperature is denoted by T3, and triple point pressure by P3. More generally, the term triple point is used to describe the conditions under which any three phases of a substance can exist in equilibrium. They can be either two solid states and one liquid state, or two liquid states and one gas state, or any other combination of these three states. This happens in the case of substances with multiple polymorphs
