Two solutions, initially at 24.60°C, are mixed in a coffee cup calorimeter (Ccal = 15.5 J/°C). When a 100.0 mL volume of 0.100 M AgNO3 solution is mixed with a 100.0 mL sample of 0.200 M NaCl solution, the temperature in the calorimeter rises to 25.30°C. Determine the ?H°rxn for the reaction as written below. Assume that the density and heat capacity of the solutions is the same as that of water. NaCl (aq) + AgNO3(aq) ? AgCl(s) + NaNO3(aq) ?H°rxn = ?