Question

In a constant-pressure calorimeter, 60.0 mL of 0.310 M Ba(OH)2 was added to 60.0 mL of 0.620 M HCl. The reaction caused the temperature of the solution to rise from 22.61 °C to 26.83 °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

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

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

                                        = 0.310*0.06   = 0.0186 moles

no of moles of HCl            = molarity * volume in L

                                           = 0.62*0.06   = 0.0372moles

The total volume of solution = 60+60 = 120ml

The density of solution          = 1g/ml

mass of solution                      = volume * density

                                                 = 120*1 = 120g

q = mcT

      = 120*4.184*(26.83-22.61)

        = 2118.78J

2 moles of HCl react with 1 moles of Ba(OH)2 to gives 2 moles of H2O

0.0372 moles of HCl react with 0.0186 moles of Ba(OH)2 to gives 0.0372 moles of H2O

ΔH for this reaction (per mole of H2O produced) = 2118.78J/0.0372mol = 56956J/mole= 56.956KJ/mole >>>answer