HI(g) has a ΔGf° that is small and positive, so HI should dissociate to some extent but its activation energy is high. HI(g) is stable at room temperature. Chemists would describe the reason for the very slow dissociation reaction as:

Question

Quizplus · Accepted Answer

The high activation energy suggests that the reaction is kinetically controlled, meaning that it is slowed down by the rate at which the reactants collide and react with each other. The small, positive ΔGf° suggests that the reaction is thermodynamically favorable, but this does not necessarily dictate the rate at which the reaction occurs.

HI(g) Has a ΔGf° That Is Small and Positive, So