NH4NO3, or ammonium nitrate, is classified as a salt that possesses weak acidic properties. It is formed from the neutralization of a strong acid, nitric acid (HNO3), and a weak base, ammonia (NH3).
When dissolved in water, NH4NO3 dissociates into ammonium ions (NH4+) and nitrate ions (NO3−). The ammonium ion can donate a proton (H+) to water, thereby decreasing the pH of the solution, which means it exhibits acidic characteristics. However, the nitrate ion does not affect the acidity or basicity significantly.
Thus, while NH4NO3 itself is not a strong acid or base, its behavior in solution leans towards being acidic due to the presence of the ammonium ion.