Question

In a constant-pressure calorimeter, 60.0 mL of 0.320 M Ba(OH)2 was added to 60.0 mL of 0.640 M HCl. The reaction caused the temperature of the solution to rise from 23.05 °C to 27.41 °C. If the solution has the same density and specific heat as water (1.00 g/mL and 4.184 J/g·°C, respectively), what is ΔH for this reaction (per mole of H2O produced)? Assume that the total volume is the sum of the individual volumes.

Answer 1

total volume   = 60 + 60 = 120ml

mass of solution   = volume * density

                              = 120*1 = 120g

   q   = mcT

         = 120*4.184*(27.41-23.05)   = 2189J

Ba(OH)2 + 2HCl ------------------> BaCl2 + 2H2O

no of moles of Ba(OH)2 = molarity*volume in L

                                        = 0.32*0.06   = 0.0192 moles

no of moles of HCl    = molarity*volume in L

                                 = 0.64*0.06   = 0.0384 moles

2 moles of Hcl produce 2 moles of H2O

0.0384 moles of HCl produce 0.0384 moles of H2O

heat energy released = 2189/0.0384   = -57005J/mole   =- 57.005KJ/mole