(a) Calculate the standard Gibbs free energies of formation of the halogen atoms X(g) at 1000. K from data available in Table 5G.2.

(b) Show how these data correlate with the X—X bond strength by plotting the standard Gibbs free energy of formation of the atoms against the bond dissociation energy and atomic number. Rationalize any trends you observe.

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TABLE 5G.2 Equilibrium Constants for Various Reactions T/K* Reaction H₂(g) + Cl₂(g) 2 HCl(g) H₂(g) + Br₂(g) 2 Hbr(g) H₂(g) + 1₂(g) = 2 HI(g) 2 BrCl(g) Br₂(g) + Cl₂(g) 2 HD(g) H₂(g) + D₂(g) 300 500 1000 300 500 1000 298 500 700 300 500 1000 100 500 1000 K 4.0 × 10³1 4.0 × 10¹8 5.1 X 108 1.9 X 10¹7 1.3 X 10¹⁰ 3.8 X 104 794 160 54 377 32 5 0.52 0.28 0.26 K 4.0 × 10³1 4.0 × 10¹8 5.1 X 108 1.9 X 10¹7 1.3 × 10¹0 3.8 X 104 794 160 54 377 32 5 0.52 0.28 0.26