During a phase change, there is no change in temperature. Below 273 degrees the reaction moves forward, and above 273 it moves backwards. How can this be proven/understood in terms of using free energy?? (If delta G is positive, the reaction moves spontaneously backwards)
I’m not so sure if my answer will fully answer your question. But I know during a chemical reaction there is climax called activation energy which is the energy need to start a reaction.