Final answer:
The enthalpy change for the conversion of V₂O₃(s) to V₂O₅(s) with oxygen is calculated as − 331.8 kJ by using Hess's Law and subtracting the enthalpy of formation of V₂O₃ from the enthalpy of formation of V₂O₅.
Step-by-step explanation:
A system's enthalpy is its heat content. The quantity of energy lost or gained during a reaction is approximately equal to the enthalpy change of the reaction. The enthalpy change for the reaction V₂O₃(s) + O₂(g) → V₂O₅(s) can be calculated using Hess's Law.
Which allows us to find the enthalpy change of a reaction by manipulating and combining chemical equations for which the enthalpy changes are known. To find the enthalpy change for the reaction of interest, we write two known reactions: 4V(s) + 3O₂(g) → 2V₂O₃(s), ΔH = − 1218.8 kJ.
4V(s) + 5O₂(g) → 2V₂O₅(s), ΔH = − 1550.6 kJ. By subtracting the first reaction from the second, we can find the enthalpy change for the desired reaction: V₂O₃(s) + O₂(g) → V₂O₅(s), ΔH = − 1550.6 kJ + 1218.8 kJ = − 331.8 kJ