When ammonium nitrate dissolves in water and the temperature of the surroundings drops, it indicates that the process is endothermic. In an endothermic process, energy is absorbed from the surroundings to break the ionic bonds in the solid, allowing it to dissolve.
As a result of this energy absorption:
- The potential energy of ammonium nitrate is higher when it dissolves compared to its state as a solid. The dissolution increases the energy of the system because energy is required to overcome the attractive forces holding the ammonium and nitrate ions together in the solid lattice.
Therefore, the most accurate statement regarding the potential energy of ammonium nitrate when it dissolves in water is:
The potential energy of ammonium nitrate is lower when it is a solid than when it dissolves.