Final answer:
To calculate the enthalpy change (ΔH) for the given reaction, use the calorimetry data to find the heat absorbed (q) with the formula q = mcΔT. Next, convert this to kJ and use the mole ratio from the balanced equation to find per mole enthalpy change.
Step-by-step explanation:
To calculate the change in enthalpy (ΔH) for the reaction Ba(OH)2 · 8H2O(s) + 2NH4SCN(aq) → Ba(SCN)2 (aq) + 2NH3(aq) + 10H2O(l), we need to use the heat absorbed by the reaction from the calorimetry data provided. According to the information, the addition of 3.15 g of Ba(OH)2·8H2O to a solution of 1.52 g of NH4SCN in a calorimeter resulted in a temperature decrease of 3.1°C.
Assuming the specific heat of the solution and products is 4.20 J/g°C and the mass of the total solution is the sum of the mass of Ba(OH)2·8H2O, the mass of NH4SCN, and the mass of 100 g of water, we can calculate the heat absorbed (q) using the formula q = mcΔT, where m represents the mass of the solution, c is the specific heat, and ΔT is the change in temperature.
Finally, we can convert q to kJ to find the enthalpy change per mole of reactants using stoichiometry and the mole ratio from the balanced chemical equation.
Barium hydroxide octahydrate: Ba(OH)2·8H2O
Ammonium thiocyanate: NH4SCN
Barium thiocyanate: Ba(SCN) 2
Ammonia: NH3