When ammonium nitrate (NH₄NO₃) is heated, it decomposes into nitrous oxide (N₂O) and water (H₂O). This reaction is exothermic, meaning it releases heat. 

  NH₄NO₃(s) → N₂O(g) + 2H₂O(g) 

The primary products are nitrous oxide (N₂O), also known as laughing gas, and water vapour. This decomposition typically occurs at temperatures below around 300°C.