Clausius–Clapeyron relation

The Clausius–Clapeyron relation, in <a href="/facts/Chemical_thermodynamics/dIQMQsd0">chemical thermodynamics</a>, specifies the temperature dependence of pressure, most importantly <a href="/facts/Vapor_pressure/whrEr96T">vapor pressure</a>, at a discontinuous <a href="/facts/Phase_transition/eLP2BY8R">phase transition</a> between two <a href="/facts/Phases_of_matter/NkHXDdN3">phases of matter</a> of a single constituent. It is named after <a href="/facts/Rudolf_Clausius/RMgFgY7I">Rudolf Clausius</a> and <a href="/facts/Beno%25C3%25AEt_Paul_%25C3%2589mile_Clapeyron/108oIBhT">Benoît Paul Émile Clapeyron</a>. However, this relation was in fact originally derived by <a href="/facts/Nicolas_L%25C3%25A9onard_Sadi_Carnot/atzzIKJB">Sadi Carnot</a> in his <a href="/facts/Reflections_on_the_Motive_Power_of_Fire/KmBj7Xq8">Reflections on the Motive Power of Fire</a>, which was published in 1824 but largely ignored until it was rediscovered by Clausius, Clapeyron, and <a href="/facts/Lord_Kelvin/LTIxG1jV">Lord Kelvin</a> decades later. Kelvin said of Carnot's argument that "nothing in the whole range of Natural Philosophy is more remarkable than the establishment of general laws by such a process of reasoning."
Kelvin and his brother <a href="/facts/James_Thomson_(engineer)/D0R4fCIK">James Thomson</a> confirmed the relation experimentally in 1849–50, and it was historically important as a very early successful application of theoretical thermodynamics. Its relevance to meteorology and climatology is the increase of the water-holding capacity of the atmosphere by about 7% for every 1 °C (1.8 °F) rise in temperature.

Clausius–Clapeyron relation open-in-new

Clausius–Clapeyron relation