How much energy (kJ) is released if 10.0g of Al(s) is reacted with excess Fe₂O₃(s) in the thermite reaction
2Al(s) + Fe₂O₃(s) $\rarr$ Al₂O₃(s) + 2Fe(l) $\Delta$ H^$\circ$ = - 822.8 kJ/mol

Question

How much energy (kJ) is released if 10.0g of Al(s) is reacted with excess Fe₂O₃(s) in the thermite reaction 2Al(s) + Fe₂O₃(s) $\rarr$Al₂O₃(s) + 2Fe(l) $\Delta$H^$\circ$ = - 822.8 kJ/mol

Quizplus · Accepted Answer

The molar mass of Al is 26.98 g/mol. For 10.0 g of Al, moles = 10.0 g / 26.98 g/mol = 0.3707 mol. The reaction releases 822.8 kJ per 2 moles of Al, so for 0.3707 mol, energy released = 0.3707 mol * (822.8 kJ / 2 mol) = 152.5 kJ, approximately 152 kJ.

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