If 200 mL of aqueous 0.862 M HCl is mixed with 20. mL of aqueous 0.431 M Ba(OH)2 in a constant-pressure calorimeter of negligible heat capacity, the initial temperature of both solutions is the same at 20.48ºC. The neutralization reaction H+(aq) + OH–(aq) → H2O(l) has a ΔHº = –56.2 kJ/mol.

What is the final temperature of the mixed solution? (Assume all solutions have a density of 1.00 g/cm3 and a specific heat capacity of 4.184 J/g•ºC)