Consider the reaction 2 Al2O3(s) -> 2 Al(s) + 3 O2(g). The heat of formation of aluminum oxide is -1669.8 kJ/mol. Calculate the heat of reaction?

Question

Consider the reaction
2 Al2O3(s) -> 2 Al(s) + 3 O2(g).
The heat of formation of aluminum oxide is -1669.8 kJ/mol. Calculate the heat of
reaction.

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Answer 1 · 2016-05-11T20:26:18

#DeltaH_(rxn)^o= Sigma n (DeltaH_f^o) _(Products) - Sigma n (DeltaH_f^o) _(Reactants)#

#DeltaH_(rxn)^o= Sigma n (DeltaH_f^o) _(Products) - Sigma n (DeltaH_f^o) _(Reactants)#

#DeltaH_(rxn)^o = (3DeltaH_f^o O_2 (g) + 2DeltaH_f^o Al ( s)) - 2DeltaH_f^oAl_2O_3(s)#

We know that the standard enthalpy of formation #(DeltaH_f^o)#of the element in its most stable form is equal to zero.

#DeltaH_(rxn)^o = (cancel(3DeltaH_f^o)O_2 (g) + cancel(2DeltaH_f^o) Al ( s)) - 2DeltaH_f^oAl_2O_3(s)#

#DeltaH_(rxn)^o = (0 +0) - 2DeltaH_f^o Al_2O_3(s)#

#DeltaH_(rxn)^o = - 2 mol. (-1669.8 (kJ)/(mol))#

#DeltaH_(rxn)^o = + 3339.6" "kJ#