I know the ideal gas law applies, but how?
So, if you take a 1600 liter jug filled with steam and try to condense it back into liquid...
...some equilibrium will be reached where the pressure in much less than atmospheric.
When water turns into steam, it occupies about 1600 times the volume (at standard temperature and pressure).
So, if you take a 1600 liter jug filled with steam and try to condense it back into liquid, the resulting water will only want to take up 1 liter of space. The rest is, well, nothing. Vacuum.
At standard temperature and pressure, you are not going to have steam. You will have water vapor. Steam is defined as water vapor at temperatures above 100°C.
If the volume remains constant at 1600 liters, the only way you can produce condensation is by lowering the temperature. Once condensation starts, you will have a water/vapor interface until that water turns to ice. You will eventually have an ice/vapor interface and that interface will continue to exist no matter how low you drop the temperature.
This is because the ice surface molecules will have a Boltzmann distribution of kinetic energies of translation at every temperature. No matter how cold the ice gets, some of its surface molecules will have sufficient kinetic energy of translation to escape the surface and become vapor molecules.
The net result is that you cannot condense all of the vapor without reducing the volume of the container to the volume that liquid water or solid ice will have at that temperature.
but how can we explain that process use "ideal gas equation"
condensation is at isothermal process. ( T = constants)
but it will give wrong explanation because P1.v1 = P2.v2
is there any better explanation use thermodynamic equation ?