Instant cold packs used to treat athletic injuries contain solid NH4NO3 and a pouch of water. When the pack is squeezed, the pouch breaks and the solid dissolves, lowering the temperature because of the following endothermic reaction.
NH4NO3(s) + H2O(l) NH4NO3(aq) ?H = +25.7 kJ
What is the final temperature in a squeezed cold pack that contains 40.0 g of NH4NO3 dissolved in 135 mL of water? Assume a specific heat of 4.18 J/(g·°C) for the solution, an initial temperature of 25.0°C, and no heat transfer between the cold pack and the environment. To find the mass of water use the density of water = 1.0 g/mL. Hint: The process takes place at constant pressure. ____ Deg Celicus