Question

When Fe2O3(s) reacts with H2(g) according to the following reaction, 2.00 kJ of energy are evolved for each mole of Fe2O3(s) that reacts. Complete the following thermochemical equation. 3Fe2O3(s) + H2(g)2Fe3O4(s) + H2O(g)

Answer 1

3 Fe₂O₃(s) + H₂(g) ⇒ 2 Fe₃O₄(s) + H₂O(g) ΔH° = -6.00 kJ

Step-by-step explanation:

Let's consider the following balanced equation.

3 Fe₂O₃(s) + H₂(g) ⇒ 2 Fe₃O₄(s) + H₂O(g)

When 1 mole of Fe₂O₃(s) reacts, 2.00 kJ of energy are evolved. Energy is an extensive property. In the balanced equation there are 3 moles of Fe₂O₃(s), so the evolved energy is:

`3molFe_(2)O_(3).(2.00kJ)/(1molFe_(2)O_(3)) =6.00kJ`

By convention, when energy is evolved it takes the negative sign. At constant pressure, the thermochemical equation is:

3 Fe₂O₃(s) + H₂(g) ⇒ 2 Fe₃O₄(s) + H₂O(g) ΔH° = -6.00 kJ

where

ΔH° is the standard enthalpy of reaction (heat released at constant pressure)