Problem 5.9.26

Solution

Consider a version of the cycle in which, after the water dries up (at the expense of the surroundings), we pour in new water, and then pour a new solution into the precipitated salt/hydrochloride.

Here one should know that for water to dry up, the temperature does not necessarily have to be the boiling point. Water molecules are always flying out of it -- it is just that if there is saturated vapor above the water, those flying out are compensated for by those flying in.

In this consideration, for the mechanism to work (it does not matter how it works; I do not know myself), the water must be able to dry up continuously, BUT this is impossible:

1. Water evaporates, and the vapor will reach saturation -- evaporation will stop.
2. Cases where unsaturated air is blown in or vapor condenses somewhere are impossible, since blowing air in and forced condensation are already useless work (or require additional heat removal).
3. We cannot provide infinite space for the vapor so that it never becomes saturated, since infinity is impossible ;)