Exemplar Problems
Problem 9 : Determine the standard enthalpy change (∆H°) for the reaction:
N₂(g) + 3H₂(g) → 2NH₃(g) Given the standard enthalpies of formation (∆H°f) for N₂, H₂, and NH₃ as 0 kJ/mol, 0 kJ/mol, and -45 kJ/mol, respectively.
Solution :
To determine ∆H° for the reaction, we can use the standard enthalpies of formation:
∆H° = Σ(∆H°f(products)) - Σ(∆H°f(reactants))
∆H° = [2∆H°f(NH₃)] - [∆H°f(N₂) + 3∆H°f(H₂)]
∆H° = [2(-45 kJ/mol)] - [0 kJ/mol + 3(0 kJ/mol)]
∆H° = -90 kJ/mol
So, the standard enthalpy change for the reaction is -90 kJ/mol.
BETA
