Could anybody refer me to some literature (textbooks or research, although preferably textbooks!) dedicated to explaining quantitatively the phenomenon of evaporation of fluids? I understand that it's related to the temperature of the fluid (and thus the kinetic energy that some molecules may have at the surface), as well as the intermolecular forces involved; I would just like to get a more detailed look at this whole subject (more specifically, I'd like to get into the evaporation of water at different temperatures, surrounded by air at room temperature). Any help on the matter would be highly appreciated.


1 Answer 1


What makes water boil/evaporate is the thermodynamic concept derived from the first and second law of thermodynamics.

You can read this article to find out the derivation from entropy to the Clapyeron equation.


$$\frac{\mathrm{d} P}{\mathrm{d} T} = \frac {\Delta{H_{vap}}}{T \Delta v}.$$

And the integral form is:

$$\ln P = -\frac{\Delta{H_{vap}}}{R}\left(\frac{1}{T}\right)+C.$$

where $P$ is the vapor pressure at that particular temperature.


For example, at room temperature (20C), the vapor pressure of water is about 2.3kPa. This means that water will evaporate until it reaches a partial pressure of 2.3kPa and then the water will attain 100% relative humidity (which means no more water can evaporate).

The driving force of this evaporation is thermodynamic related. Evaporation occurs in order for the system to reach thermodynamic equilibrium.

Below is a phase diagram - the water-water vapor phase boundary is simply the plot of vapor pressure against temperature.

enter image description here

  • $\begingroup$ "too scale"? This from WP? Probably should fix...but the "scale drawing" is also fairly useless w/o a scale. $\endgroup$
    – Nick T
    Commented Jan 11, 2016 at 23:42

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