When a substance dissolves in water, heat is released?

Question

All help is appreciated. Thank You.

Answer 1

When substance dissolve in water, the ions are dissociated. They can be exothermic and release heat (ex. CaCl2, used for ice melt) or they can be endothermic and absorb heat (ex. NH4NO3 used in cold packs)

It all goes back to the bonds. If the undissolved substance has stronger bonds thanthe ions, then energy is released. The reverse if the ions have a higher energy level than the original substance.

Answer 2

fiction from the reaction, "conservation of energy",enrgy is never lost, just changed. and "for every action there is a equal and opposite reaction".