Instant cold packs, often used to ice athletic injuries on the field, contain ammonium nitrate and water separated by a thin plastic divider. when the divider is broken, the ammonium nitrate dissolves according to the following endothermic reaction: nh4no3(> nh4 ^+(aq) + no3^-(aq). in order to measure the enthalpy change for this reaction, 1.25 g of nh4no3 is dissolved in enough water to make 25.0 ml of solution. the initial temperature is 25.8 degrees c and the final temperature (after the solid dissolves) is 21.9 degrees c. calculate the change in enthalpy for the reaction. (use 1.0g/ml as the density of the solution and 4.18 j/g . degrees c as the specific heat capacity.)