Question

As a rule of thumb, vapor condensation usually happens at the interface between the system and the heat reservoir. Now, according to my analysis below, it is the only way for vapor to condense, which implies the near impossibility of condensation in the bulk of vapor. :

As the temperature drops, within the vapor system, whose thermodynamic behavior can be described by a canonical ensemble, energy is favored over entropy. That is, the energy should escape from the system to the heat reservoir to create a large entropy overall. This means that the system has the tendency to evolve into the low energy configuration when the temperature drops. Thus, for such a phase transition to take place, the passage of energy from the system to the reservoir is crucial. The case for vapor is unique in that its only access to the heat reservoir is on the surface, while for other systems, such as the Ising model, it has access to heat reservoir (the phonons, for instance) within the bulk so that we can see bubbles of broken symmetry, domain walls, forming inside the bulk. At the interface between vapor system and the heat reservoir, the mechanism for such a transfer of energy is the conversion of kinetic energy of vapor into the phonons of the reservoir. In the bulk of vapor, however, there is no direct way for the energy to be transferred. Classically, the energy released by forming a droplet can only be carried to reservoir by vapor. This process is extremely inefficient, and its explicit mechanism is obscure. Quantum mechanically, it should be possible that the release of energy is in the form of radiation, where the radiation background plays the role of a heat reservoir. Clearly, these two passages of transferring energy to the reservoir should be negligible compared to the mechanism taking place at the interface. So, in any realistic cases, condensation of droplets never happens in the bulk without impurity.

It remains to be checked whether such an analysis is physically well-founded and consistent with the experiment.

Answer 1

Condensation involves the transfer of energy from a substance, with the release of latent heat increasing the temperature of the surroundings. This occurs efficiently at surfaces, where energy can be readily transferred, leading to dynamic equilibrium in closed systems. Condensation in the bulk of vapor is unlikely without additional mechanisms.

Step-by-step explanation:

The process of condensation requires the transfer of energy away from a substance, allowing vapor to transition into a liquid state. This heat transfer results in the release of latent heat, which can increase the temperature of the surroundings despite the association of condensation with cold surfaces. The energy involved in condensation is the same as that required for vaporization, thus it can be calculated using the equation Q = mLy, where Q is the heat added or removed, m is the mass, and Ly is the specific latent heat of vaporization.

At the surface of a liquid or vapor, molecules are in a position to transfer energy to the surroundings more readily. In the case of a closed container, vapor equilibrium can be reached where vaporization and condensation rates are equal. This dynamism between the phases demonstrates a dynamic equilibrium, important in understanding the vapor pressure concept. Within the bulk of vapor, without other mechanisms like the presence of impurities or surfaces, the transfer of energy is less efficient, rendering bulk condensation less likely under typical conditions.