The highly exothermic thermite reaction, in which aluminum reduces iron(III) oxide to elemental iron, has been used by railroad repair crews to weld rails together. 2Al(s) + Fe₂O₃(s) → 2Fe(s) + Al₂O₃(s) ΔH = −850 kJ
What mass of iron is formed when 725 kJ of heat are released?

Question

Quizplus · Accepted Answer

Given that the reaction releases 850 kJ of heat to produce 2 moles of iron, we can set up a proportion to find out how much iron is produced when 725 kJ of heat is released. The molar mass of iron (Fe) is approximately 56 g/mol. Since 850 kJ produces 2 moles (or 112 g) of iron, 725 kJ will produce $725 kJ \times \frac{112 g}{850 kJ} = 95 g$.

The Highly Exothermic Thermite Reaction, in Which Aluminum Reduces Iron(III)