Why is the dissolution of potassium nitrate ENDOTHERMIC?

This reaction is favoured by entropy, but disfavoured by enthalpy. How? As usual, entropy wins. I think those portable cold packs (for first aid use) contain a blister of water inside a sample of the potassium salt. When you come to use it, you break the blister (i.e. keeping the pack intact), and the cold pack is placed over the sprain or injury, to reduce the swelling and provide topical relief.

The dissolution of potassium nitrate is endothermic because it requires the absorption of energy from the surroundings to break the bonds between the potassium, nitrate, and water molecules, resulting in a decrease in temperature.

The dissolution of potassium nitrate (KNO3) is endothermic because it requires energy input to break the bonds between the potassium ions (K+) and the nitrate ions (NO3-) in the solid crystal lattice of potassium nitrate. This energy is needed to overcome the attractive forces holding the ions together in the solid state. As these bonds are broken during dissolution, energy is absorbed from the surroundings, resulting in a decrease in temperature and making the process endothermic.