The reaction is HCl + NaOH -> NaCl + H2O for HCl: (0.15L)(0.4M)(1mol H2O/1mol HCl)=0.06mol H2O for NaOH: (0.15L)(0.5M)(1mol H2O/1mol NaOH)=0.075mol H2O Since 0.06<0.075, we choose 0.06. (-56kJ/mol H2O)(0.06mol H2O)= -3.36kJ Solution The reaction is HCl + NaOH -> NaCl + H2O for HCl: (0.15L)(0.4M)(1mol H2O/1mol HCl)=0.06mol H2O for NaOH: (0.15L)(0.5M)(1mol H2O/1mol NaOH)=0.075mol H2O Since 0.06<0.075, we choose 0.06. (-56kJ/mol H2O)(0.06mol H2O)= -3.36kJ.