Final answer:
The reason for the greater enthalpy change in the reaction of Ba(OH)2 with H2SO4 compared to HCl is due to the high lattice energy involved in the formation of BaSO4, which releases greater energy than the formation of BaCl2 in the latter reaction.
Step-by-step explanation:
The reason why the enthalpy change for the reaction between barium hydroxide (Ba(OH)2) and sulfuric acid (H2SO4) is greater than that for Ba(OH)2 and hydrochloric acid (HCl) can be attributed to several factors, including the different properties of the acids and the bond energies involved in the reactions.
Sulfuric acid is a strong, dibasic acid and has a higher oxidation state of sulfur compared to other acids such as sulfurous acid (H2SO3). When Ba(OH)2 reacts with H2SO4, it forms barium sulfate (BaSO4) and water, where the formation of BaSO4 involves the combination of Ba2+ and SO42- ions with high lattice energies, leading to a greater release of energy.
In contrast, when Ba(OH)2 reacts with HCl, it forms barium chloride (BaCl2) and water. The bond between Ba2+ and Cl- in barium chloride has a lower lattice energy than that in barium sulfate, resulting in a smaller release of energy during the formation of the solid salt. The release of energy in these reactions is reflected in their respective enthalpy changes.