The molar entropies of HI(g),H(g) and I(g) at 298K are 206.5,114.6, and 180.7 J mole−1 K−1 respectively. Using the Δ G0 given below,Calculate the bond energy of HI.
H(g) → H(g) + I(g); Δ G0 = 271.8 kJ
298.3 kJ/mole
HI(g) → HI(g) + I(g)
Δ G0 = Δ G − TΔ S0
Δ S0 = ∑ S0 products − ∑ S0 Reactants
= (114.6 + 180.7) − (206.5)=295.3 − 206.5 = 88.8
Δ G0 = Δ H − TΔ S
Δ H = Δ G0 + TΔS = 27.18 + 298 × 88.8 = 271.8 + 26462.8 Joules
= 271.8 + 26.4628 = 298.3kJ/mole