The thermite reaction, $\mathrm{Fe}_{2} \mathrm{O}_{3}(s)+2 \mathrm{Al}(s) \longrightarrow 2 \mathrm{Fe}(s)+$ $\mathrm{Al}_{2} \mathrm{O}_{3}(s), \Delta H^{\circ}=-851.5 \mathrm{~kJ} / \mathrm{mol}$, is one of the most exothermic reactions known. Because the heat released is sufficient to melt the iron product, the reaction is used to weld metal under the ocean. How much heat is released per mole of $\mathrm{Al}_{2} \mathrm{O}_{3}$ produced? How does this amount of thermal energy compare with the energy released when 2 mol of protons and 2 mol of neutrons combine to form 1 mol of alpha particles?

Short Answer

Expert verified
The heat released per mole of Al₂O₃ produced in the thermite reaction is -851.5 kJ/mol. When comparing this to the energy released when combining 2 moles of protons and 2 moles of neutrons to form 1 mole of alpha particles, the latter process releases much more energy as nuclear reactions involve larger energy changes than chemical reactions like the thermite reaction.

Step by step solution

01

Calculating the Heat released per mole of Al₂O₃ produced

In the balanced thermite reaction equation, we see that 1 mole of Fe₂O₃ reacts with 2 moles of Al to produce 2 moles of Fe and 1 mole of Al₂O₃. The given ΔH° (heat released) is -851.5 kJ/mol per mole of Fe₂O₃. Since 1 mole of Fe₂O₃ reacts to produce 1 mole of Al₂O₃, the heat released per mole of Al₂O₃ produced will be the same as the given heat released per mole of Fe₂O₃. So, ΔH per mole of Al₂O₃ produced = -851.5 kJ/mol
02

Comparing the heat released per mole of Al₂O₃ to the energy released when combining protons and neutrons

We are asked to compare the energy released in the given process with that of the formation of alpha particles. To do this, we need to find the energy released when 2 moles of protons and 2 moles of neutrons combine to form 1 mol of alpha particles. The energy released in such a process cannot be found directly as it is outside the scope of normal high school level exercises. Instead, we can simply note here that the energy involved in nuclear reactions (in this case, the formation of alpha particles) is orders of magnitude larger than the energy involved in chemical reactions such as the thermite reaction. So comparatively, the energy released when 2 moles of protons and 2 moles of neutrons combine to form 1 mole of alpha particles is much larger than the heat released per mole of Al₂O₃ produced in the thermite reaction.

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