Re: [Phys-L] phase change

[Diego Saravia <dsa@unsa.edu.ar>]

> Well, I would again recommend a kinetic explanation, as I tried to outline
> in an earlier post.  The rate at which particles sublimate off the solid
> into the gas is a strongly increasing function of temperature, because
> kinetic energies increase with temperature and a particle needs a certain
> amount of kinetic energy to overcome the binding energy and break free.  On
> the other hand, the rate at which particles condense from the gas onto the
> solid is a decreasing function of temperature if the pressure is held
> fixed; this is because higher T means faster particles and hence more
> momentum from each collision, and so the collisions must occur less
> frequently (due to lower density).  So if you plot the increasing
> sublimation rate and the decreasing condensation rate as functions of
> temperature, the lines must cross at some precise T.  That's the equilbrium
> temperature.
But if you are heating the solid you will have more sublimation than
condensation

But the interface will have the equilibrium temp.