Which of the following chemical equations is the formation r

Which of the following chemical equations is the formation reaction of Fe2O3(s) from its constituent elements in their standard states? The standard enthalpy of formation (Hfo) values are given in the table below.

Substance Hfo (kJ/mol)

Fe(s) 0 O2(g)

0 O3(g) 142.7

FeO(s) 272.0

Fe2O3(s) 824.2

A) 4 Fe(s) + 3O2(g) 2Fe2O3(s)

B) 2 Fe(s) + O2(g) Fe2O3(s)

C) 2 Fe(s) + O3(g) Fe2O3(s)

D) Fe2O3(s) 2Fe(s) + O2(g)

E) 2 FeO(s) + O2(g) Fe2O3(s)

Solution

The standard enthalpy of the reaction when 1 moe of a substance is formed from its constituent elements in yheir standard states is called heat of formation.

Here the concerned substance is Fe₂O₃(s). Its constituent elements are Fe and Oxygen. The standard states of Fe is Fe(s) and standard state if oxygen is O₂(g).

Both reactions A and B shows the foration of Fe₂O₃(s) from Fe(s) and O₂(g), but only equation A is balanced, so option A is the answer