When calculating the enthalpy change ($\Delta H$) of a reaction using bond energies, what is the general principle applied?
Question 3
Consider the reaction: $H_{2}(g) + I_{2}(g) \rightarrow 2HI(g)$. Given the average bond energies: H-H = $436 \text{ kJ/mol}$, I-I = $151 \text{ kJ/mol}$, H-I = $299 \text{ kJ/mol}$. Calculate the enthalpy change ($\Delta H$) for this reaction.
Question 4
What is a primary reason why calculations of reaction enthalpies using average bond energies are often estimations rather than exact values?
Question 5
If a chemical reaction has a positive enthalpy change ($\Delta H > 0$) when calculated using bond energies, what does this imply about the reaction?
