Introduction Lately, i have been attempting to develop a better understanding of thermodynamics, but i have encountered a few problems. I considered that endothermic solvation, (e.g. dissolving KNO3 in water) is essentially the same as an absorption heat pump. This idea was based on the simple fact, that dissolving KNO3 (Potassium Nitrate) in water, absorbs heat energy; evaporating the water heating it up, returns the potassium nitrate to a solid form, where it then can be used once again to absorb heat energy. Before coming to a conclusion and incorporating a consideration into my understanding i always make sure they are congruent with the laws and principles. In this case with a thought experiment I tested the congruency of how i would consider a solvation heat pump to behave and the second law of thermodynamics. Thought Experiment Solid KNO3 is dissolved in water until the solution is saturated. As this solvation is endothermic, the solution is colder than lab that this is conducted in, but after a duration of time it reaches equilibrium with the lab, which has not changed temperature during this process. This solution is poured into compartment A of a container that is sealed and perfectly insulated. Heat is introduced to this container with the use of a Carnot heat pump, that extracts heat from the lab and heats the container above the temperature of the lab. As the temperature increase inside this container, the solution begins to evaporate. Compartment A is mainly taken up by the solution and the water vapour is forced to move through a small tube at the top of compartment A to compartment B, which is significantly larger than compartment A. The container is ceases to be heated once all the water has been evaporated. As the water is a gas it it is evenly diffused throughout the container. The far majority of the water resides in compartment B due to the size difference between the compartments, but all the potassium nitrate remains in compartment A in solid form. The heat gradient between the container and the lab is then utilised by a Carnot heat engine. As he temperature falls, the water within each compartment condensing as liquid. The container returns to the temperature of the lab with liquid water residing in both compartments with the far majority residing in compartment B. The the far majority of the KNO3 remains in compartment A as a solid, with the rest dissolved in the water in compartment A. Issue In this thought experiment, the potassium nitrate solution absorbed heat energy from the lab, which is then expelled when it returns to a solid. The majority of the heat energy is not reabsorbed when the water re-condenses, as most of the water condenses in a different compartment. As this energy is not reabsorbed, it is utilised by the Carnot heat engine and a portion of this heat energy is converted to a higher quality form of energy. I would conclude that such a conclusion is a violation if the second law of thermodynamics. This as with my other post “the altitude hypothesis” have a very similar problem as my undeveloped understanding suggests that ‘ heat energy can be converted to potential energy allowing a heat gradient to be formed and utilised, reducing entropy.’ If anyone out there can explain the flaw in this reasoning, it would be greatly appreciated.