Final answer:
The enthalpy change (ΔH) is specified for a balanced chemical reaction, but we cannot calculate it for the given amounts of reactants without knowing the moles of Fe₂O₃ reacting with 0.750 mol of Al2O3.
Step-by-step explanation:
The student is asking about the enthalpy change (ΔH) for a reaction where 0.750 mol of Al2O3 reacts with 2.00 mol of Fe. According to the given balanced equation 2 Al(s) + Fe₂O₃(s) → 2 Fe(s) + Al₂O₃(s) +815.5 kJ, the ΔH is -851.5 kJ for 1 mol of Fe₂O₃, which is equivalent to -425.8 kJ/mol of Al since 2 mol of Al are consumed. If we want to find the ΔH when 0.750 mol of Al2O3 reacts, we would have to adjust this value accordingly.
Since no moles of Fe₂O₃ are given and the amount of Fe provided (2.00 mol) is in excess compared to the stoichiometric coefficient of Fe in the balanced equation (which is a 1:1 ratio to Fe₂O₃), we would need to know the corresponding moles of Fe₂O₃ that would react with the 0.750 mol of Al2O3 to find the exact value for ΔH. However, since these values are not provided, we cannot calculate a specific ΔH for this scenario.