Final answer:
The thermite reaction involves the reaction between aluminum and iron(III) oxide. The enthalpy change for the reaction is -851.5 kJ/mol of Fe₂O₃. When 5.00 g of aluminum reacts with a stoichiometric amount of Fe₂O₃, the amount of heat evolved is 79.0 kJ.
Step-by-step explanation:
The thermite reaction involves the reaction between aluminum (Al) and iron(III) oxide (Fe₂O₃) to produce iron (Fe) and aluminum oxide (Al₂O₃). The balanced chemical equation for this reaction is: 2 Al(s) + Fe₂O₃(s) → 2 Fe(s) + Al₂O₃(s).
The enthalpy change for this reaction, or the amount of heat evolved, is -851.5 kJ/mol of Fe₂O₃. To determine the amount of heat evolved when 5.00 g of aluminum reacts with a stoichiometric amount of Fe₂O₃, we need to convert the grams of aluminum to moles and then use the molar ratio from the balanced equation.
Given that the molar mass of aluminum is 26.98 g/mol and the molar ratio between aluminum and Fe₂O₃ is 2:1, we can calculate the amount of heat evolved using the formula:
Heat evolved = (5.00 g Al) / (26.98 g/mol Al) * (-851.5 kJ/mol) = 79.0 kJ