In a constant-pressure calorimeter, 65.0 mL of 0.320 M Ba(OH)2 was added to 65.0 mL of 0.640 M HCl. The reaction caused the temperature of the solution to rise from 21.98 °C to 26.34 °C. If the solution has the same density and specific heat as water (1.00 g/mL and 4.184 J/g·K, respectively), what is ΔH for this reaction (per mole of H2O produced)? Assume that the total volume is the sum of the individual volumes.

2 answers

(65ml)(0.320M Ba(OH)2)+(65ml)(0.640M HCl)
=>0.065(0.32)mole Ba(OH)2+ 0.065(0.64)mole HCl
=>0.0208mole Ba(OH)2 + 0.0416mole HCl
=>0.0208mole Ba(OH)2 + 0.0416 mole HOH
gram yield HOH = 0.0416mole(18g/mole) = 0.749g HOH
Delta T = (26.34-21.98)C = 4.36C
q = mcT =(0.749g)(4.184J/gC)(4.36C) = 13.7 Joules/0.749g HOH
Molar Delta H = (13.7)/(0.749/18)Joules/mole = 328 Joules/mole HOH yield
Correction - BaCl2 on product side of rxn.