1. The problem statement, all variables and given/known data A quantity of 2.00x10^2 mL of .862 M HCl is mixed with 2.00x10^2 mL of .431 M Ba(OH)2 in a constant-pressure calorimeter of negligible heat capacity. The initial temperature of the HCl and Ba(OH)2 solutions is the same at 20.48 C. For the process H+(aq) + OH-(aq) --> H2O (l) the heat of neutralization is -56.2 kJ/mol. What is the final temperature of the mixed solution? 2. Relevant equations I'm thinking all I need is q=ms delta t 3. The attempt at a solution q=(heat of neutralization per mol)(number of moles H2O) q= -56.2 kJ/mol x (200 mL*.862mol/1000mL) = -9.69 kJ If -9.69 = q = ms(T(f)-T(i)) Then T(f) = q/ms + T(i) = -9690 J/(400g)(4.184g/J*C) + 20.48*C = 121.8 degrees C The answer should be 26.3 degrees C. Any help?