Final answer:
To calculate ΔS°298, you need to use the relevant S° values from Appendix G. For the reaction N₂(g) + 3H₂(g) ⟶ 2NH₃(g), ΔS°298 is -198.1 J/K per mole of N₂. For the reaction N₂(g) + 5/2O₂(g) ⟶ N₂O₅(g), ΔS°298 is 161.3 J/K per mole of N₂.
Step-by-step explanation:
To calculate ΔS°298 for the given changes, we need to use the relevant S° values from Appendix G. Let's calculate them step by step:
a) N₂(g) + 3H₂(g) ⟶ 2NH₃(g)
ΔS°298 = 2S°(NH₃) - [S°(N₂) + 3S°(H₂)]
Let's substitute the values:
ΔS°298 = [2 mol NH₃ × 192.8 J/(mol·K)] - {[1 mol N₂ × 191.6 J/(mol·K)] + [3 mol H₂ × 130.7 J/(mol·K)]}
ΔS°298 = -198.1 J/K (per mole of N₂)
b) N₂(g) + 5/2O₂(g) ⟶ N₂O₅(g)
ΔS°298 = S°(N₂O₅) - [S°(N₂) + 5/2S°(O₂)]
Let's substitute the values:
ΔS°298 = [1 mol N₂O₅ × 304.3 J/(mol·K)] - {[1 mol N₂ × 191.6 J/(mol·K)] + (5/2) [1 mol O₂ × 205.0 J/(mol·K)]}
ΔS°298 = 161.3 J/K (per mole of N₂)