To calculate the standard enthalpy change H for the formation of [Fe H2O 6]Cl3 from its constituent ions, we need to consider the stoichiometry of the reaction and the enthalpy changes of formation Hf for each species involved.The balanced equation for the formation of [Fe H2O 6]Cl3 is:Fe3+ aq + 6H2O l + 3Cl- aq [Fe H2O 6]3+ aq + 3Cl- aq Now, we can use Hess's Law to calculate the standard enthalpy change for the reaction. Hess's Law states that the total enthalpy change for a reaction is the sum of the enthalpy changes for each step in the reaction.For this reaction, we have two steps:1. Formation of [Fe H2O 6]3+ from Fe3+ and 6H2O:Fe3+ aq + 6H2O l [Fe H2O 6]3+ Hf = +123 kJ/mol2. Formation of [Fe H2O 6]Cl3 from [Fe H2O 6]3+ and 3Cl-:[Fe H2O 6]3+ aq + 3Cl- aq [Fe H2O 6]Cl3 s Hf = ?We are given the Hf for Cl- as -167 kJ/mol. Since there are 3 moles of Cl- in the reaction, the total enthalpy change for the formation of 3 moles of Cl- is 3 -167 kJ/mol = -501 kJ/mol.Now, we can use Hess's Law to calculate the Hf for the formation of [Fe H2O 6]Cl3:Hf [Fe H2O 6]Cl3 = Hf [Fe H2O 6]3+ + Hf 3Cl- - Hf Fe3+ - Hf 6H2O Since the enthalpy change of formation for elements in their standard state is zero, we can ignore the terms for Fe3+ and 6H2O:Hf [Fe H2O 6]Cl3 = +123 kJ/mol - -501 kJ/mol Hf [Fe H2O 6]Cl3 = +123 kJ/mol + 501 kJ/molHf [Fe H2O 6]Cl3 = +624 kJ/molTherefore, the standard enthalpy change H for the formation of [Fe H2O 6]Cl3 from its constituent ions is +624 kJ/mol.