workload homework

Question

How much energy is evolved during the formation of 98.7 g of Fe, according to the reaction below?

Fe2O3(s) + 2 Al(s) → Al2O3(s) + 2 Fe(s) ΔH°rxn = -852 kJ
How much energy is evolved during the formation of 98.7 g of Fe, according to the reaction below?

Fe2O3(s) + 2 Al(s) → Al2O3(s) + 2 Fe(s) ΔH°rxn = -852 kJ. which of these answer?

753 kJ
1.51 x 103 kJ
4.20 x 103 kJ
241 kJ
482 kJ

Answer 1

Fe2O3(s) + 2 Al(s) ==> Al2O3(s) + 2 Fe(s) ΔH°rxn = -852 kJ

According to the above equation, you generate 852 kJ of energy for every 2 moles of Fe that are formed.  So, we can calculate moles of Fe equivalent to 98.7 g, and then find the energy liberated.

moles of Fe formed = 98.7 g x 1 mole/55.85 g = 1.77 moles Fe

Energy evolved = 1.77 moles Fe x -852 kJ/2 moles Fe = 754 kJ 

ANSWER = 753 kJ