Chapter 19, Problem 82E

H₂ reacts with the halogens (X₂) according to the reaction:

${\text{H}}_{\text{2}}\left(g\right)+{\text{ X}}_{\text{2}}\left(g\right) \rightleftharpoons \text{2HX}\left(g\right)$

where X₂ can be Cl₂. Br₂ or I₂. Use the thermodynamic data in Appendix IIB to calculate $\Delta H°$, $\Delta S°$, $\Delta G°$ and K_p, for the reaction between hydrogen and each of the three halogens. Which reaction is most spontaneous? Least spontaneous?
What is the main factor responsible for the difference in the spontaneity of the three reactions? Does higher temperature make the reactions more spontaneous or less spontaneous?