Chemical cold packs contain two pouches, one containing solid ammonium nitrate and the other containing water (often dyed for no real reason).

Chemical cold packs contain two pouches, one containing solid ammonium nitrate and the other containing water (often dyed for no real reason). When the contents of the pouches mix, the ammonium nitrate dissolves in the water, NH4NO3(s) → NH4+(aq) + NO3-(aq) The dissolving process is endothermic. The reaction absorbs approximately 326 J/g of ammonium nitrate. To lower the temperature of 220. g of water by 20.0°C, how many grams of ammonium nitrate would you need to dissolve?