OU NanoLab/NSF NUE/Bumm & Johnson

The Kelvin Equation

The surface tension causes an increased chemical
potential for a molecule inside
a droplet. This is manifested as an
increase in the vapor pressure *P *of the liquid droplet compared to that of the bulk
liquid *P*0. The is described
by the Kelvin equation. Two radii of
curvature appear in the result,
*r**1* and *r**2*. For a sphere both terms are equal, but for a
cylindrical surface one
term vanishes because one radius is infinite (flat).

The other parameters are:

*γ* the surface tension,

the molar volume of the liquid,

R the gas constant, and

*T* the absolute temperature.

the molar volume of the liquid,

R the gas constant, and