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?

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.

Answer 1

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

Explanation:

`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`