What is Triple point?
The '''triple point''' of any substance is the combination of [[temperature]] and [[pressure]] at which it exists in its [[solid]], [[liquid]], and [[gas]]eous state all at once, in [[equilibrium]]. The temperature of the triple point of [[water]] is a commonly used [[physical constant]] which is used to define temperature [[scale]]s and calibrate temperature-measuring systems. ''By definition'', the temperature of the triple point of water is 273.16 [[Kelvin]], 0.01°C, or 32.018°F at a pressure of 611.5 Pa (less than 1% of [[atmospheric pressure]]). One degree [[Celsius]] is defined as 1/273.16<sup>th</sup> part of the triple point of water. This fixes the temperature scale as defined in the [[ITS 90]], which is the international temperature scale of 1990. This scale is developed as a practical approximation of the [[thermodynamics|thermodynamical]] temperature scale. {{chem-stub}} {{States of matter}} [[Category:Chemistry]] [[Category:Thermodynamics]]