19. When 1.00 L of 1.00 M barium nitrate solution at 25.0℃ is mixed with 1.00 L of 1.00 M sodium sulfate solution at 25.0℃
in a calorimeter, the white solid barium sulfate forms, and the temperature of the mixture increases to 32.1℃. Assuming
that the calorimeter absorbs only a negligible quantity of heat, the specific heat capacity of the solution is 4.18 J/℃ · g,
and the density of the final solution is 1.0 g/mL, calculate the enthalpy change per mole of barium sulfate formed.
(A) 59 KJ/mol (B) -59 KJ/mol (C) 30 KJ/mol (D) -30 KJ/mol (E) 89 KJ/mol